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| Dietary Treatment of Obesity Chapter 18 – Johanna T. Dwyer, DSc, RD and Kathleen Melanson, PhD, RD, LD w/ assistance of Lisa N. Faucon, MS, RD TO OBTAIN A DOWNLOAD OF THIS CHAPTER IN WORD OR PDF FORMAT, CLICK HERE |
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| Dietary Treatment of Obesity Chapter 18 – Johanna T. Dwyer, DSc, RD and Kathleen Melanson, PhD, RD, LD w/ assistance of Lisa N. Faucon, MS, RD TO OBTAIN A DOWNLOAD OF THIS CHAPTER IN WORD OR PDF FORMAT, CLICK HERE |
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Obesity is a chronic medical condition that requires long-term therapy to achieve improved health outcomes [1, 2, 3].
Self-initiated approaches to weight reduction are often ineffective. People often believe that there is a quick and easy remedy for curing obesity. In fact there is no easy way. The only way to keep off excess weight is through lifelong obesity prevention behaviors involving physical activity, balanced with a healthy diet [1, 3]. Health professionals can help people be more effective in maintaining a healthy weight or losing weight when necessary.
Health professionals often ignore treating obesity because they regard it as being unlikely to improve with usual therapy. However, a modest (10%) weight reduction in obese people is attainable and often results in clinical improvements of several health-related parameters, even if the individual remains clinically obese [1, 4, 5]. This information should encourage health professionals and patients that they need not be overwhelmed by their inability to meet excessively ambitious or unrealistic weight loss goals [4, 6]. Smaller weight losses can still bring considerable health and social benefits.
There is a great deal of misinformation about obesity in this country today. According to a survey by the Natural Marketing Institute, 59% of the general population would benefit from losing weight. Of them, 26% used weight loss products in the past year, 21% used prescriptions to manage or maintain their weight, 18% used over the counter medications to maintain and/or manage their weight and 11% used weight loss supplements [7]. Only some of these strategies are effective.
Weight management counseling of overweight and obese patients deserves reconsideration and reemphasis by physicians because it carries such a great potential for health benefits. Obese patients receiving weight reduction advice from their physicians are significantly more likely to embark on weight loss attempts than those who do not, and yet less than 42% of obese individuals reported that they received weight loss recommendations from their physicians [8]. These findings underscore the need for increased physician and health professional involvement in obesity treatment [2, 9, 6]. When physicians are appropriately aware of and include recommendations for lifestyle changes in counseling their obese patients, results are promising [8, 10]. Even more important, physicians should stress achievement and maintenance of a healthy weight before obesity becomes apparent.
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Table 1. US Department of Agriculture 2005 Dietary Guidelines for Americans US Department of Health and Human Services [11] |
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Risk Intervention and Goals |
Key Recommendations |
Special Population Recommendations |
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Adequate nutrients within calorie needs |
Consume a variety of nutrient dense foods/beverages with the basic food groups Limit intake of saturated and trans-fats, cholesterol, added sugars, salt, and alcohol. Balance intake of calories with energy needs |
Adults age >50 should consume a vitamin B12 supplement Women planning pregnancy should consume foods rich in heme iron and/or iron-rich plant foods; also a dietary supplement with synthetic and fortified sources of food containing folic acid in addition to other foods naturally high in folic acid or foods fortified with folic acid Women in the first trimester should consume a folic acid supplement in addition to food forms of folate
Older adults, those with dark skin, and those not exposed to sufficient sunlight should consume extra vitamin D from vitamin D fortified foods and/or supplements |
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Weight Management |
Maintain body weight in a healthy range by balancing calories with energy expended Prevent gradual weight gain by making small decreases in food/beverage calories and increased physical activity |
Overweight adults should strive for slow steady weight loss by decreasing calories and increasing physical activity while maintaining adequate nutrient intake. Overweight children should lose weight only after consultation with a healthcare provider to ensure the reduction of body weight does not interfere with growth and development Pregnant women should ensure that their weight gain is appropriate under supervision of healthcare provider Breastfeeding women can have moderate weight loss if they have gained weight but it should not be so rapid as to compromise nursing infants
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Physical Activity |
Engage in at least 30 minutes of moderate-intensity physical activity on most days of the week. Greater health benefits can be obtained by engaging in physical activity more vigorous intensity or longer duration Manage body weight gain by engaging in 60 minutes of moderate-to-vigorous intensity activity on most days per week Sustain weight loss by engaging in 60-90 minutes of daily moderate-intensity physical activity while not exceeding caloric intake requirements Achieve over-all physical fitness by including a variety of exercise modalities (cardiovascular, stretching, resistance, and calisthenics) |
Children and adolescents-engage in 60 minutes of physical activity on most, preferably all, days of the week Pregnant women – if no medical or obstetric complications are present, engage in 30 minutes or more of moderate intensity physical activity most days of the week; avoid falls and abdominal trauma Breastfeeding women there is no contraindications to exercise Older adults – regular physical activity helps to reduce functional declines associated with age |
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Fats |
<10% of calories from saturated fat < 300 mg/day cholesterol Limit saturated and trans-fatty acids Total fat 20%-35% of total calories; emphasize polyunsaturated and monounsaturated fatty acids (ie fish, nuts, vegetable oils); this can be accompanied by emphasizing, low-fat or fat-free meat, poultry, milk, and dairy products |
Children and adolescents: - ages 2 to 3 30%-35% calories from fat - ages 4 to 18 25% - 35% calories from fat |
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Sodium and Potassium |
Consume potassium-rich foods daily such as frits and vegetables
Consume <2,300 mg sodium/day |
Middle-aged and older adults, African Americans, and those with hypertension should aim for: - Sodium intake < 1,500 mg/day - Potassium intake 4,700 mg/day |
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Alcohol |
Limit alcohol to 1 drink per day for women; 2 drinks per day for men
Do not begin alcohol consumption if not presently using |
Restrict alcohol in women of child-bearing age who are planning pregnancy, pregnant women, children and adolescents, medication warnings/interactions, certain medical conditions |
The 2005 Dietary Guidelines for Americans (Table 1) provide assistance in maintaining and achieving a healthy weight and eating pattern [11]. So do Mypyramid.gov and the DASH diet recommendations (Table 2). This chapter briefly reviews steps health professionals can take to help their patients manage their weight more effectively, and to reduce weight by dietary means when that is necessary.
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Table 2. DASH Diet Recommendations [12] |
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Type of food |
Number of Servings per day for a 1600 Calorie Diet |
Number of Servings per day for a 2,000 Calorie Diet |
Number of Servings per day for a 3,100 Calorie Diet |
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Grains and Starches
(Include at least 3 whole grain foods per day) |
6 |
7-8 |
12 |
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Fruits |
4 |
4-5 |
6 |
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Vegetables |
4 |
4-5 |
6 |
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Low Fat or non fat Dairy Foods |
2 |
2-3 |
4 |
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Lean meats, fish poultry |
1.5-2.5 |
2 or less |
2.5 |
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Nuts, seeds, and legumes |
3 per week |
4-5 per week |
6 per week |
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Fats and sweets |
Limited |
Limited |
Limited |
The growing propensity to becoming overweight in the United States indicates that attention to weight control and maintenance are not matters that should be confined to those who already are overweight. Weight control has health advantages, and therefore maintaining or achieving a healthy weight is important for all Americans. In weight control, an ounce of prevention is worth a pound of a cure. Once weight and fatness have surpassed healthy levels, they are difficult to reduce. Therefore it is important for health professionals to monitor the weights of all their patients and to provide anticipatory guidance so that those who are already at healthy weights remain so. The 2005 Dietary Guidelines for Americans (Table 1) stress maintaining a body weight in the healthy range, by balancing calories from foods and beverages with calories expended, by preventing gradual weight gain over time, by making small decreases in food and beverage calories, and by increasing physical activity. However, this is easier said than done. The remainder of the chapter will assist in operationalizing these behaviors.
This section outlines a stepwise approach for assessing and treating obesity by dietary means.
Before any patient is placed on a reducing diet, medical assessment of the patient’s weight, fat distribution and health risks is essential.
Weight should be measured without clothing on electronic scales, which provide accurate weights even for heavy patients. Height is best measured with a wall-mounted stadiometer or against a wall rather than on beam-balance scales, which are unsteady and unreliable. Body fat is difficult to measure directly in clinical practice but the body mass index (BMI), provides a better measure of fatness than weight alone, and can be calculated using the following formulas.
BMI= (weight lbs x 703) ÷ height in inches2
or
BMI = weight kg ÷ height in meters2
Table 3 presents classifications of BMI values for adults, as established by the National Institutes of Health. These data are based on abundant data associating higher BMI levels with higher health risks. Although individuals with the same BMI often differ somewhat in the
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Table 3. Classification of Weight Status by Body Mass Index (BMI) |
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Classification |
BMI (Kg/m2) |
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Underweight |
<18.5 |
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Normal weight |
18.5-24.9 |
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Overweight |
25-29.9 |
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Obesity Class 1 |
30-34.9 |
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Obesity Class 2 |
35-39.9 |
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Extreme Obesity Class 3 |
>40 |
amount of body fat this is still a useful approximation which can be performed quickly and inexpensively. Individuals with a BMI under 18.5 are classified as underweight, whereas those with a BMI over 25 are considered overweight; those over BMI 30 are classified as class 1 obesity, those over BMI 35 as class 2 obesity, and those over BMI 40 as extreme obesity.
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Table 4. Classification of Risk of Type 2 Diabetes, Hypertension and Cardiovascular Disease Associated with Weight |
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Classification of Fatness Status by BMI and Waist Circumference |
Increase in Disease Risk for Type 2 Diabetes, Hypertension and Cardiovascular Disease Over Normal Weight and Waist Circumference |
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Waist
circumference |
Waist
circumference |
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Underweight (BMI <18.5) |
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Normal (BMI (18.5-24.9) |
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Overweight (BMI 25-29.9) |
Increased |
High |
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Obese Class 1 (BMI 30-34.9) |
High |
Very high |
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Obese Class 2 (BMI 35-39.9) |
Very high |
Very high |
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Extreme Obesity Class 3 (BMI >40) |
Extremely high |
Extremely high |
Two simple tools for monitoring weight are to keep track of weight changes and body mass index (BMI). Increases of more then 1 BMI unit (which is about 10-14 pounds depending on height and weight) signal the need for instituting preventive measures.
The distribution of fat on the body as well as its sheer amount also alters risk. The reasons for this are becoming clear as the role of adipose tissue as an endocrine organ is more fully understood. Excess abdominal fat in the viscera, characterized by an accumulation of fat centrally (sometimes referred to as android "apple" or abdominal fat distribution) is associated with greater risk of certain chronic degenerative diseases than a peripheral fat deposition pattern (gynoid "pear" or lower body fat pattern).
Although the causal associations are a matter of debate in the scientific literature, [13, 14] measuring waist circumference in addition to BMI is still clinically useful in assessing risk posed by body fat distribution [15].
Visceral and subcutaneous fat are difficult to measure in office practice. The waist circumference, taken at the level of the umbilicus with a plastic non-stretchable measuring tape, is a reasonable proxy for assessing the likely size of visceral fat deposits and the extent of abdominal obesity. Waist circumference is easier to measure and more straightforward to interpret than waist-to-hip ratios. It is being increasingly used as the standard in assessing central vs. peripheral fatness. The cut-points for increased risk are a waist circumference of greater than 35 inches in women or greater than 40 inches in men. Although the usefulness of these absolute values have been questioned due to the many possible confounding variables in their relationship with health, monitoring changes over time is still advocated [16]. Table 4 shows how risks of weight related conditions such as type 2 diabetes, hypertension, and cardiovascular disease increase with greater BMI and waist circumference. Patients at high risk may need increased monitoring and treatment of blood pressure, blood cholesterol and other cardiovascular risk factors. Two other factors that increase risk further are physical inactivity and smoking. They exacerbate the severity of the other risk factors present as well as increasing risks themselves in other ways. Elevated serum triglycerides are another marker for increased cardiovascular risk.
The presence of other risk factors or clinically evident diseases further increases the health risk of obesity. Table 5 describes different conditions that further add to the adverse health effects of the obesity itself. They are also problems that must also be managed with other modalities in addition to weight control. Although weight loss can help to lower elevated blood pressure, blood glucose, both total and low density lipoprotein (LDL) plasma cholesterol and triglyceride levels, and raise low high density lipoprotein (HDL) cholesterol levels in those with abnormal values. Additional pharmacologic therapy may also be necessary to bring some patients into the ranges.
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Table
5. Risk Factors and Comorbidities that Increase the Risks of
Overweight |
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Level of Risk |
Conditions |
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High Absolute Risk |
Established coronary heart disease or other atherosclerotic disease |
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Type 2 diabetes |
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Sleep Apnea |
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High absolute Risk if 3 or More of These Risk Factors are Present |
Hypertension |
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Cigarette smoking |
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High low-density lipoprotein cholesterol |
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Low high density lipoprotein cholesterol |
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Impaired fasting glucose |
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Family history of early cardiovascular disease |
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Age: >45 in men or >55 in women |
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Increased Risk |
Increased surgical risk Psychological disorders such as depression Osteoarthritis Hirsutism (presence of excess body and facial hair (Surgeon General Call to action to prevent and decrease overweight and obesity) |
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Gallstones |
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Stress incontinence |
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Gynecologic problems such as amenorrhea and menorrhagia |
All individuals with a BMI over 25 and those at lower BMI’s with a high waist circumference and two or more of the risk factors listed in Table 5 are potential candidates for weight reduction. The goal of weight control is reduction of weight and maintenance of healthy body weight over the long term. If this is impossible, at least prevention of further weight gain should be attempted. Those with a very high BMI (over 35) are unlikely to be able to achieve sufficient fat loss on a usual low calorie diet of 1200 to 1500 calories without regimes that continue for many months. They should be referred for care to a multidisciplinary team specializing in obesity for very low calorie diets and other treatments that may be more effective than usual low calorie diets.
Some individuals whose weight is normal and who are without weight associated health problems also may wish to lose weight. These fortunate few need to have their concerns about diet addressed, but should not embark on reducing diets since there is no medical reason for them to do so. They should be discouraged and counseled to follow MyPyramid.org (figure 1), the DASH diet (Table 2), and the Dietary Guidelines for Americans (Table 1). If excessive concern about weight continues and the patient refuses not to diet, counseling may be helpful from a psychologist or psychiatrist to alleviate their concerns.
The procedures described above provide a reasonable assessment of the health risks associated with obesity and the potential health benefits accruing from weight loss. Weight control requires behavioral change, which cannot happen without patient consent and "buy-in". Therefore, risks need to be communicated and patient readiness needs to be ascertained. Unfortunately, those who are most concerned about their weights are not necessarily those who are at the highest health risk. Those who are at high health risk are often unaware of how serious their problems are, or are in deep denial about them. The consequences of excess weight must be raised and carefully explained. Many of the obese may fall into this category and they must be motivated to lose weight.
Once patient readiness and willingness to lose weight has been ascertained, a plan of attack needs to be jointly devised with the patient. Some patients are ready to start a treatment program immediately. For those patients who are not ready to act at all, the issue should be deferred and brought up again at the next visit, rather than dropping the subject entirely. Others are unable or unwilling to embark on a weight reduction program at all. However, they may be willing to take steps to avoid further weight gain or perhaps to work on other risk factors such as cigarette smoking, and they should be encouraged to do so.
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Figure 1. [17] |
Normal weight patients who wish to control their weight may also ask for help. They should be counseled to avoid weight gain and provided with helpful information on healthy eating and physical activity levels. Such recommendations are summarized in Tables 1, 2 and on the web at www.mypyramid.gov (see Figure 1).
Diet therapy is not for everyone. Weight reduction with dietary treatment is in order for virtually all patients with a BMI of 25-30 with comorbidities and for all patients with a BMI over 30 [18]. However, usual low calorie diets are unlikely to suffice to treat those with BMI >35. Referral to a multidisciplinary obesity treatment team is in order for them so that more heroic measures can be used if necessary (ie: very low calorie diets, gastric bypass surgery, and pharmacological treatment).
Prescription drugs may also be considered for those with a BMI of 25-30 if comorbidities are present, and for heavier patients even in their absence if the patients are unable to lose weight with dietary measures alone. However, weight loss drugs are only adjuncts to, rather then substitutes for, reducing diets. A reducing diet will still be necessary.
Only two prescription drugs are currently approved for long-term use in weight reduction. Sibutramine (Meridia) is an appetite suppressant that works centrally in the brain to decrease appetite. Its advantages include slightly greater net weight losses and longer maintenance of losses than diet and physical activity alone. Disadvantages include chronic increases in blood pressure in some patients and high costs for the drug [19].
Orlistat (Xenical) is a drug that operates at the level of the gut to inhibit pancreatic lipase and fat absorption. It also increases net weight loss, at least over the short run, compared to a reducing diet alone. Recently Orlistat has been approved for over-the-counter (OTC) sales under the name Alli [20]. Orlistat may also foster adherence to low-fat reducing diets because of the fat malabsorption it induces, which may negatively condition some patients to decrease their fat and overall caloric intakes. Orlistat’s disadvantages are malabsorption, sometimes accompanied by anal leakage, and decreased absorption of fat-soluble vitamins. The drug is not effective without a hypocaloric diet. Dietetic counseling is helpful in managing the weight loss, since a low fat low calorie diet is also necessary.
Phentermine, phendimetrazine, diethylpropion and benzpheamine are modestly effective anorectic agents approved for short-term use (12 weeks in a 12 month period) by the Food and Drug Administration (FDA) [19].
The off-label use of bupropion (Wellbutrin), a drug originally approved by the FDA for aiding in smoking cessation, has become popular in the past few years for weight control. Bupropion enhances norepinephrine and weakly blocks dopamine reuptake and is being studied for the treatment of obesity. Bupropion could be considered if a patient presenting with obesity wanted to quit smoking and lose weight [19]. Short term side effects most often reported are agitation, dry mouth, insomnia, headache, nausea, constipation, and tremor. However, its long-term effects on weight loss are not clear, and its use must be accompanied by a low-calorie diet.
Topiramate is an anticonvulsant that was originally approved to treat epilepsy. It is also sometimes used off-label for its weight loss effects. However, adverse effects have also been reported, most commonly difficulty with memory, parathesia, difficulty concentrating, and mood problems. This drug is approved by the FDA for epilepsy only, and not for weight loss [19].
Byetta (exenatide and pramlitide) products are sometimes used in treating the comorbidities of obesity. Both affect the gastrointestinal hormones that regulate glucose homeostasis, gastric emptying, and satiety. Exenatide (Byetta) is used as an adjunctive therapy for improving glycemic control in patients with type 2 diabetes among patients and who also take metformin or sulfonylurea. Pramlintide is an adjunctive therapy for patients with type 1 or type 2 diabetes who use insulin at mealtimes. Usually patients with diabetes gain weight with better glucose control however with these drugs better blood glucose control is often associated with weight loss, at lease in preliminary studies. The most common side effect for these medications is nausea [19].
Cannabinoid (CIB) receptor antagonists are another promising class of pharmacologic treatments for obesity that make reducing diets more effective. CB1 receptors are located in the brain, gastrointestinal tract adipose tissue, heart, pituitary gland, and adrenal glands and if they are stimulated, these receptors increase appetite. Blockage of these receptors is thought to decrease appetite. One drug of this type, Rimonabant, approved for use in Europe since 2006, shows promising weight loss effects. However, there are also reports of adverse reactions including nausea, depressed mood, anxiety, and diarrhea [19]. The FDA recently decided that Rimonabant carries too much risk to approve for use in the United States.
Drugs for weight loss are of limited efficiency, some patients cannot afford them and all have side effects. Patients who are likely to respond to drugs do so within the first month of therapy. If they fail to lose 5 lbs in the first month, the drug is unlikely to be effective and it may be appropriate to discontinue use.
Surgical options such as gastric bypass and lapband surgery are recommended only for patients classified as Obese class 3 (BMI>35) or Obese class 2 (BMI >30) with comorbidities. Patients who opt for the surgical route must adhere to certain dietary recommendations before the surgery is performed to show they are able to follow a hypocaloric diet. After surgery, food intake is altered because their gastric capacity is considerably limited [21]. The post operative weight reduction surgery diet used in one hospital is shown in Table 6, but there is no standard, widely accepted protocol for diet therapy at present. Dietary restrictions must continue long term after surgery.
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Table 6. Post Gastric Bypass Surgery Diet [21] |
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Stage 1 |
One ounce of water per hour typically in the hospital on the day of surgery |
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Stage 2 |
Non caloric clear liquids, usually in the hospital the day after surgery |
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Stage 3 |
1) 3-4 small meals per day, each consisting of a high protein non sugar added shake such as Isopure or Carnation Instant Breakfast 2) Water or non-caloric non-carbonated clear liquids between meals 3) Goals of this stage are to drink 64 oz fluid per day 50-60 grams of protein a day for women and 60-70 grams of protein per day for men 4) This stage lasts 2-3 weeks
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Stage 4 |
1) Small portions of moist, ground/pureed foods. 2) Begin supplementing with a multivitamin plus minerals and Vitamin D with Calcium 3) Aim for 60-70 grams of protein per day 4) This stage lasts 4-5 weeks |
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Stage 5 |
1) Small portions of low-fat or low-sugar solid foods 2) At least 64 ounces of fluid per day 3) Aim for 60-80 grams of protein 4) Continue to take supplements 5) Follow this 6-8 weeks after surgery and follow up with a Registered Dietitian |
The health professional’s approach to setting goals and treating obese patients must be non-judgmental and focused on an acceptable weight to achieve good health outcomes rather than simply reaching a lower body weight [22, 23, 24]. Everyone wants to be healthy. But, patients are often ready to abandon long term "healthy" measures if they feel that a risky weight loss strategy will work over the short term. They need to understand that the primary medical reason for losing weight is health and that therefore weight control measures must be healthy. By concentrating on improving health and risk factors rather than simply on loss of weight, an excessive emphasis on the aesthetic and cosmetic aspects can be avoided and the health aspects can be highlighted [25].
Everyone also wants to look their best, and many obese people yearn for a slimmer figure. While some cosmetic improvement is possible with usual weight losses, they are rarely as much as the client desires to achieve. Therefore it is important for the physician and other health professionals to stress the health advantages of even modest weight losses.
The health professional should begin therapy by working with the patient to set a realistic healthier weight. From the medical perspective, the weight goal is to maximize heath related effects while minimizing disruption to the patient’s quality of life from the weight reducing regimen. The physician is uniquely qualified to define and communicate what a "healthier" weight is to the patient since he/she has access to measurements of weight related risk factors that can be expected to decrease if weight is lost.
Weight reduction targets that are optimal vary depending on the patient’s weight and comorbidities. The patient needs to be informed that progress toward healthier weight goals should involve a gradual approach that minimizes health risks and is timed to the patient’s readiness, motivations, and reachable short-term targets. Patients need to understand that aesthetic and cosmetic effects of weight loss are "extras" but that the primary medical concern is primarily to help the patient lose enough weight to improve or maintain health.
The target is usually to achieve a loss of about 10 percent of body weight over a period of six months, and to keep weight at this lower level thereafter. The goal is moderate enough to be achievable and reduces fatness and weight enough to decrease some obesity-related risk factors [5]. The six-month limitation to the diet is because after about 6 months most patients have difficulty sustaining adherence, and weight plateaus as resting metabolic rate and energy output decreases.
Patient weight goals depend on their motivation, the salience of weight as an issue to them, their perceptions of health risk, and other priorities in their lives. Some patients simply are not motivated to lose weight, or are motivated but are not willing to do so at present. It makes no sense to give an unmotivated patient a goal that cannot be achieved. It is far better to come to agreement about the steps he/she is willing to take now to begin to deal with their other health problems.
For patients who are already highly motivated or become so when they are told about the related health risks, the physician’s job is easier. These patients’ weight targets are often unrealistically low (e.g. targets of 30% or more of body weight) and their time frames for achieving losses unrealistically short (e.g. a few weeks rather than months). Patients’ ideals for weight reduction are unrealistic; two or three times the 8-15% losses that motivated patients usually achieve [26]. For them, advice and counseling on more realistic targets and time frames is helpful. Because patient weight goals are often very different from those of their healthcare providers the health professional must do a good deal of negotiation and explanation to convince the patient.
Definitions of success are always patient-specific, but health professionals can emphasize the importance of health goals as a major part of the equation. The reduction of risk factors, even if weight is not lost, is "success" from the health standpoint. For some patients, prevention of further weight gain after years of slow, steady increase is progress. The maintenance of a reduced weight, even if it is still within the range of clinically defined obesity is also a "success" since it reduces health risks. Thus, the definition of successful obesity treatment must be broadened to encompass goals other than weight loss, and these broader health goals also need to be communicated to patients. For example, some outcomes to target in addition to a hypocaloric diet might include improved metabolic profiles such as reduced blood pressure, fasting blood glucose, increased daily physical activity and fitness, greater consumption of fruits, vegetables and fiber or reduction in dietary fat. Changes in specific unhealthful habits such as smoking or overindulgence in alcoholic beverages are also reasonable goals from the psychological standpoint and may help enhance self esteem, self-efficacy, quality of life and functional capacity [1, 3].
Patients are also often unreasonably hard on themselves and believe that if they are to undertake weight reduction, drastic measures are necessary. Therefore a healthy weight goal consisting of an initial loss of 1-2 BMI units is often much less extreme than the dramatic weight loss patients think of as ideal. However, such a goal is much more likely to be achievable. A loss of 10% of body weight, if sustained, significantly reduces risks of coronary heart disease and other comorbidities [27, 5]. It also improves cosmetics and appearance. Patients need to realize that perfection is unlikely, but some steps in a positive direction are possible.
The physician plays an important role by giving patients permission to adopt more realistic and achievable targets and helps patients to achieve them.
The 10% weight loss target can be achieved in most patients with a caloric deficit of 500-1000 Calories per day or 1-2 pounds a week. A weight reduction plan of about 1000-1200 Calories for women or 1200-1600 Calories for men along with increased physical activity and behavioral modification will usually produce this caloric deficit. With a caloric deficit of 500-1000 Calories a day after 6 months with perfect adherence losses would theoretically be between 26 and 52 pounds. In actuality, losses are usually about 20-25 pounds, since adherence is never perfect.
A decrease of one BMI unit usually represents a loss of 10-15 pounds depending on height and weight. A decrease in 2 BMI units over 6 months is another way of stating the weight loss goal. Reductions of this magnitude in weight usually decrease several risk factors such as blood glucose and blood pressure and thus should result in better overall health. Clothing should fit better and appearance should be trimmer. If further weight reduction is necessary after 10% of body weight is lost, it can be attempted with a new reducing diet after weight has been maintained for several months at a healthier level.
If left to their own devices most dieters may become more sedentary during weight loss especially if diets are very low in calories. This is because a very negative energy balance reduces exercise tolerance and maximal power output and increases perceived exertion [28]. Therefore, conscious efforts to increase physical activity while dieting require attention.
Many overweight patients have already tried in the past to lose weight on their own. For example, in the United States nearly half of women and more than a third of men report that they are attempting to lose weight [22]. However, with self-directed efforts, their reasons are often aesthetic or social rather than health-related. The goals they adopt are often unrealistically ambitious, the information they obtain on weight management is often inaccurate, and the motivation and support they receive from both health professionals and peers is frequently inadequate. Solo efforts often may fail and lead to discouragement and a sense of futility [29]. The vital role of the physician and other health professionals is to provide the motivation, information, counseling, and support that patients need to be more successful in their weight loss efforts.
Evidence-based reviews of successful weight control techniques increasingly emphasize the importance of individualized, multidisciplinary care, a health-outcomes focus, realistic goal setting and making permanent lifestyle changes, including an increase in physical activity [30, 31].
The specific underlying factors that induce a chronically positive energy balance and thus the development of obesity differ among individuals. Furthermore, daily lifestyle, environment, resources and social situations may vary considerably. It is appropriate to individualize the weight reduction strategy in order to promote adherence, and thus success [3]. There is no single diet that works for everyone. Different dietary approaches for maximizing adherence are successful to varying degrees in different individuals. If asked, patients can usually identify some strategies that have worked for them in the past, on which the health professional can build. Previous pitfalls can also be identified and incorporated into the new weight loss strategy. Candidates for weight reduction should discuss the approach that best suits their needs with their physician and/or dietitian. In addition to energy content, individual food selections, meal frequency and many other factors that can be tailored to make the diet better suit the individual from the psychological, social, medical and nutritional standpoints. Some factors to consider include the diet’s cost, convenience, how it approaches treatment of co-existing health conditions, and whether it assists patients to adopt strategies for healthful life-long weight maintenance [32, 33].
Throughout the weight loss management program, it is vital that the patient be counseled on sound eating patterns. Some dietary education topics that should be discussed to help patients on their weight loss regimens are listed in Table 7. The National Institutes of Health (nutrition.gov), the American Dietetic Association (www.eatright.org) and other organizations provide materials, checklists, guidelines, menus and recipes to assist in such patient education [3, 30]. Resources for health professionals and their patients can also be accessed at websites such as MyPyramid.gov and those from the American Heart Association, American Diabetes Association, and the American Cancer Society.
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Table 7. Nutrition Education Topics for Weight Management |
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Patients should be encouraged to maintain daily records of their food and beverage intake. The record keeping process often increases awareness of consumption, and promotes dietary adherence. The patient should be encouraged to study the records each week and to identify an eating related behavior that can be changed may help him or her to focus effort.
For the individual who is already overweight, successful weight control first requires a hypocaloric phase in which dietary energy intake is reduced while energy output is increased (or at least not decreased). This phase is referred to as the "energy deficit" or "hypocaloric phase" of weight control.
The essential components of weight reduction, regardless of the type of diet, are decreased energy intake, increased energy output through physical activity, behavioral modification of lifestyles, and alterations in the larger environment that foster these measures. Together, these measures contribute to the energy deficit necessary to reduce weight. Although this chapter focuses on dietary measures in the treatment of obesity, all reasonable treatment programs for overweight should include the full complement of these measures, including physical activity and behavioral modification.
Obesity results from the accumulation of excessive body fat as adipose tissue. Numerous experimental studies under controlled conditions have established that an energy deficit of approximately 3500 Calories is required for an overweight person to lose one pound of fat. Although compensatory changes in resting metabolism, the energy cost of work, and discretionary physical activity may occur which sometimes alter this figure by 100-200 Calories, over the long term this relationship of 3500 Calories per pound of fat holds up quite well. Thus it is the size of the energy deficit between actual energy needs and the energy output that determines the slope of decline in fatness over time.
The goal of the dietary treatment of obesity in the energy deficit phase is to decrease body fat stores without unduly depleting the lean body mass or otherwise compromising health. The lean body mass includes cells in skeletal muscle and the vital organs. During weight loss, some lean tissue is always lost along with the fat, but the goal is to minimize this loss [33]. While weight is being lost, body stores of other nutrients such as water, vitamins, minerals and electrolytes must be maintained. Fortunately, dietary strategies are available to minimize loss of lean tissue and other nutrients. For example, a systematic review of the scientific literature has demonstrated that more lean tissue is lost if the energy deficit of the diet is too great and the rate of weight loss is too quick, whereas inclusion of exercise (both cardiovascular and resistance) help to minimize lean tissue loss [33]. These must be incorporated into sound dietary treatment plans.
Some of the many factors that contribute to patients losing less weight than they expect to while on reducing regimens and what to do about it are described below.
People vary in their eating patterns from day to day. Weight reduction prescriptions are sometimes made by suggesting that the patient aim for a caloric deficit of approximately 500 Calories per day to achieve a weight loss of about 1 pound per week. However, this is an abstract goal that is difficult to implement since the patient does not know how much he/she is eating in the first place. Since most people vary greatly in their food intake from day to day, they have great difficulty recognizing whether in fact they are eating less than previously. For this reason simply urging patients to "eat less" of certain foods in general is unlikely to help. More specific advice is more actionable. For example, cutting down portion sizes of high calorie, frequently consumed foods, eliminating a second cocktail, etc.
The average healthy adult American male consumes approximately 2800 Calories per day, and the average female about 1800 Calories. Yet, such intakes are seldom actually reported when people recall or report their intakes. Instead, much less is reported. The reporting of energy intakes is difficult even for individuals who have been trained to report accurately. Even small omissions or portion size and serving mistakes can subtract hundreds of calories from usual intakes. Many days of observation are necessary since energy balance is only achieved over weeks, not days. Thus a report from any given day is certain to contain considerable random error if it is used to estimate usual calorie intake. Even more serious errors of a systematic nature (biases) are also present. Underreporting of energy intakes is common and large (e.g. 20%) in virtually all people, and it is particularly common among the overweight [34]. Studies with objective biomarkers of energy output such as doubly labeled water indicate that underreports may be as great as 1200 Calories per day in very obese persons [35, 36]. Indeed, subjective reports of energy intake are often so low that those who report them should be losing weight when in fact, they are actually gaining! It is biologically impossible to gain weight on a hypocaloric diet, and so underreporting must be considered [37].
The most common problem is that the patient’s weight loss is less, not more then expected. This is largely a result of underreporting of intake. When overweight people report their intakes by recall, they often underestimate their intakes by 30-40%. They are likely to make similar mistakes in underestimating their intakes on reducing diets because of difficulties in portion size judgement, forgetting, the social desirability of reporting adherence to the prescribed regimen, and other factors. For example, many people underestimate or forget their very large food intake on weekends or forget to count in alcohol, snacks, or double portions of foods. Thus, on a 1200 Calorie diet actual consumption may actually be 1600 Calories or much more.
Methods for assisting dieters to decrease these intake reporting errors include the use of household measures or weighing scales to determine amounts eaten more precisely and the use of food diaries to help in self-monitoring of food intake. Portion-controlled liquid meal replacements, frozen low calorie entrees, and other foods that are fixed in their portion sizes may be helpful in controlling intakes at specific meals.
Consistency in reporting does not necessarily mean that the report is accurate especially among the very heavy. Underreporting is especially pronounced in the severely obese, women, smokers, those of low educational and socioeconomic status [35]. Those who are under-reporters tend to be so consistently [35]. In spite of all these limitations, self-reports are useful to the patient and counselor alike for obtaining clues on dietary patterns and portion sizes that may be helpful in counseling the patient and monitoring adherence. However, it is important to recognize their limitations.
Self-reports of energy output as measured by physical activity questionnaires have also been validated using doubly labeled water methods. Lengthy questionnaires used for research purposes are quite good [38]. However, the shorter questionnaires of the type that are used clinically are not accurate for individuals [39]. As is the case with dietary reports, physical activity questionnaires may be useful for self-monitoring, but should not be used for prescribing or assessing energy intakes or outputs precisely. Step counters (accelerometers) have become popular in recent years. Step counters with uniaxial movement in a vertical plane are less accurate than triaxial monitors such as the Tracmore and these are often used as self-monitoring tools [40]. They quantify physical activity in a demonstrable way. Goals such as "10,000 steps a day" can be prescribed and the patient can self-monitor his or her progress in reaching the goal.
Compensatory decreases in physical activity occur on reducing diets, particularly if they are very restrictive in energy. These decreases result in slowed weight loss. As a rule of thumb, for every 500 Calorie deficit, compensatory decreases in energy output due to decreased resting metabolic rate, discretionary physical activity and the decreased energy cost of work involving moving the body are approximately 165 Calories, leaving only 335 Calories that actually contribute to weight loss. Thus the caloric deficit again may prove to be less than anticipated and predicted weight loss is therefore less then expected [41]. Some data also suggest that energy balance is more strongly defended during energy deprivation that it is during energy surplus, impeding weight loss to a greater extent than weight gain [42, 43, 44]. In part, this retarding effect on weight loss may be due to downward alterations in resting metabolism and in non-obligatory physical activity and thermogenesis.
Dramatic alterations in weight may occur on reducing diets, particularly in the first few weeks on a severely hypocaloric regime (with deficits of 1000 Calories per day), and on ketogenic diets [45, 46]. These fluid shifts are larger on some reducing diets than others, depending on the caloric level and macronutrient composition of each diet. For example, diets that increase obligatory urine volume due to greater urinary loads of nitrogen or other solutes will result in increased fluid losses from the body. Excess loss of lean tissue is also associated with large body water losses because tissues such as muscle are approximately 73% water. Fluid losses are also more apparent on hypocaloric regimes that are very low in carbohydrate (<100gm and especially <50gm carbohydrate). Shifts in water balance may cause very dramatic deviations from a linear slope of weight loss. They may also result in very rapid weight accumulation over a few days during periods of non-adherence which result from storage of glycogen and water with carbohydrate refeeding after a period of carbohydrate deprivation. This is because for every one gram of glycogen stored, three grams of water are associated with it. Thus, gains or losses of glycogen are associated with changes in body water balance and weight.
Over the long run, fat loss and weight loss closely parallel each other. This is not necessarily true over the short run. The amount of weight that is lost over time, particularly over the short run of several days depends not only on the energy deficit from current needs, but on adherence to the weight reduction plan, and on shifts in water balance, which may be considerable over the short run. These shifts may accentuate the fat loss that is actually occurring. Such considerations, which are often unrecognized by patients, make many skeptical about whether such predictions actually apply to them.
From the clinical standpoint, hypocaloric diets must be defined in terms of the energy needs of the individual, since it is the size of the energy deficit that will determine the physiological effects expected. Calculations for estimating energy expenditure and thus energy needs are provided in Table 8.
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Table 8. Estimating Energy Expenditure [11] |
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Males >19 years old EER= 662-(9.53 x Age in years) + PA [(15.91* Weight in Kg) + (539.6 * Ht in m)] |
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Females>19 years old EER= 354 –(6.91 * Age in years) + PA [(9.36 * Weight in Kg ) + (726x Ht in m)] |
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Adjusted BW = Ideal Body weight + 0.25 (Weight in Kg-Ideal BW in Kg ) = Adjusted BW in Kg |
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PA values for Different Physical Activity Levels |
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Sedentary Light physical activity associated with typical day-to-day life. |
Low Active Walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life. |
Active Walking more than 3 miles per day at 3 to 4 miles per hour, in addition light physical activity associated with typical day-to-day life: 60 minutes of at least moderate intensity physical activity |
Very Active
|
|
Males |
1.00 |
1.11 |
1.25 |
1.48 |
|
Females |
1.00 |
1.12 |
1.27 |
1.45 |
The major determinant of weight loss on reducing diets is size of the actual and not the prescribed caloric deficit. All diets that reduce caloric intake to about 1400-1500 Calories in most American adults (lower in females) will result in weight loss if they are adhered to perfectly, regardless of their macronutrient composition [47]. Therefore, the caloric level of the diet requires attention first and foremost; after this, other characteristics of the diet can be considered. Diets that reduce caloric intake relative to energy expenditure result in weight loss. The optimal diet for weight loss of sedentary people in the absence of alterations in physical activity is thought to be one that provides roughly 1000-1600 Calories per day, depending on sex, weight, and physical activity level, regardless of its macronutrient composition.
Low calorie diets of 1000-1200 Calories for women and 1200-1600 Calories per day for men are currently recommended by the National Institutes of Health for weight loss in most individuals [1, 30]. The rationale is that on such regimens a deficit of approximately 500-1000 Calories per day will be created, which should result in slow progressive weight loss of 1-2 pounds per week. The dietary composition of the recommended reducing diet is similar in macronutrients to that of the National Heart, Lung and Blood Institutes (NHLBI) Step 1 diet to decrease risks of high blood cholesterol and blood pressure [1]. Two sample menus and other materials at 1200 and 1600 Calories and many aids to assist the physician are provided in the NIH monograph [30]. The MyPyramid.gov website also provides such materials that can be accessed by consumers.
It is important to recognize that when using fixed 1200-1600 Calorie reducing diet plans such as those provided in NIH recommendations that even with perfect adherence, individuals will vary greatly in their weight loss. This is because their resting energy needs and physical activity, and thus their energy outputs, often differ markedly.
The National Institute of Health’s Obesity Initiative sponsored an evidence based review of low calorie diets [30]. It found that on average diets such as these reduced body weight by an average of 8% over 3-12 months of treatment, and that the losses were accompanied by decreases in abdominal fat, which is the type of adipose tissue deposition that is associated with highest chronic disease risk. However, no improvements were noted in cardio respiratory fitness as measured by VO2 max unless the dieters also increased their physical activity [1].
Any diet, regardless of its caloric level, that provides less than half of an individual’s energy needs is a VLCD for that individual. Virtually all adults have energy needs that exceed 1000 Calories a day, and therefore any diet below 500 Calories, and for many individuals, diets below 800 calories are VLCD. But other regimens that are higher in calories may also be VLCD for some people with very high energy needs using this same rule of thumb; for example, a 1200 Calorie diet prescribed to a man whose usual intake is 3000 Calories would also qualify as a VLCD.
These VLCD diets are reserved for special uses and for individuals at high risk because of their potential for greater adverse metabolic effects and the consequent need for more extensive medical monitoring. VLCD are often used when the health risks from obesity are particularly acute and threatening so that it is imperative to lose weight. Other individuals can usually reduce just as well on a LCD with less risk and discomfort [48].
Individuals with BMI’s >30 or those with lesser degrees of overweight but many comorbidities (BMI > 27 with comorbidities) and who have failed to lose weight with more conservative approaches are candidates for therapy. Medical contraindications include recent myocardial infarction, cardiac conduction disorders, history of cardiovascular disease, renal or hepatic disease, cancer, type 1 diabetes and pregnancy. Behavioral contraindications to their use include bulimia nervosa, major depression, bipolar disorder, substance abuse, and acute psychiatric illness. The advantages of the VLCD for patients include a rapid improvement in blood pressure, blood glucose, serum lipids and often-psychological status. For those who require surgery, the rapid loss of weight may improve their surgical risks.
The hallmarks of the VLCD are the low calorie level and a relatively high percent of protein; 0.8g-1.5g/kg body weight [49]. Protein needs are elevated on VLCD because in the hypocaloric state the efficiency of protein utilization for maintaining the body’s lean cell mass is lessened. Also, very heavy people who often are candidates for therapy have a larger lean body mass and thus more lean tissue as well as much more fat than their smaller peers. Even after adjustment for their greater fatness, total protein needs, which are most highly associated with the size of the lean body mass are elevated. Therefore higher protein levels may help to preserve protein nutritional status. VLCD also have extremely low fat content and relatively low carbohydrate levels, making them ketogenic. Without special formulation or supplementation, the VLCD is inadequate in several vitamins and minerals, especially potassium, calcium, iron, zinc, vitamin B6, copper and possibly other nutrients.
There are two major types of VLCD currently in use; commercial and "home made" preparations. The commercial preparations include powdered products rich in egg or milk based proteins that are mixed with water and consumed 4-5 times daily. The commercial products must provide at least 70 gm of protein by law and often contain much higher amounts of high quality protein (70-100gm), 50-100 gm carbohydrate, and up to 15 gm fat per day, plus vitamins and minerals in amounts to meet the Recommended Dietary Allowances. These products are formulated under Food and Drug Administration regulatory specifications. These products are convenient and have a predictable and adequate composition when used as directed. Their major disadvantage compared to home preparations is their higher cost. The formulas or prepackaged meals are relatively choice-free and help dieters avoid contact with conventional foods, which in some cases may facilitate dietary adherence and remove temptation.
Several commercial weight loss programs are available that provide an entire program of VLCD plus the other essential aspects of a sound weight control program, including dietetic advice, exercise, behavioral modification, and supervision during the VLCD and post VLCD phases. The choices include the programs of HMR (Health Management Resources) and Optifast (Novartis Nutrition). These programs employ health professionals who are trained in weight management and a structured program that encourages adherence. The major disadvantage is that they are expensive ($3000-$34000 for 26-28 weeks) and costs may not be covered by health insurance [49]. Also there is the uncertainty that the weight which is lost will remain so over the long run. Therefore an investment of effort in long-term weight management is also mandatory.
The "home made" VLCD regimens are sometimes referred to as "protein sparing fasts", or "protein sparing modified fasts" (PSMF). They are usually based on lean meat, fish or poultry and a few other foods plus supplements of 2-3 gm potassium chloride and a multivitamin/multimineral supplement in amounts approximating the Recommended Dietary Allowances. Without such supplementation, they may be inadequate. When patients are provided with appropriate dietetic counseling, health supervision by a physician who is experienced in the use of VLCD, and other aspects of a complete weight reduction program, these formulations are also safe and generate rapid weight loss. The extremely hypocaloric versions of VLCDs which are low in carbohydrate and sodium promote a mild ketosis that gradually leads to a diuresis and rapid loss of weight in the first several days on the diet.
Evaluation of general health and cardiac status is important prior to the institution of VLCD. Evaluation of medication dosages and
physician monitoring during the regimen are also important. Many practitioners begin the regimen with a 2-4 week LCD phase to assess the ability to comply with a restrictive regimen and to begin the weight loss process. This is followed by a 12-16 week VLCD phase; the regimen is limited to this amount of time to avoid excessive loss of lean tissue. The VLCD phase is followed by a 12-14 week refeeding phase of transitioning back to usual foods and gradually increasing caloric levels. This helps to avoid rapid weight changes due to refeeding with restoration of glycogen stores and shifts in water balance. The refeeding phase also provides a time for assisting the dieter to plan a maintenance diet on conventional foods and to solidify a physical activity schedule. VLCD are most effective when administered as part of a more general weight control program that includes physical activity, nutrition education, behavioral modification and attention to decreasing other risk factors. If additional weight loss is needed, it is recommended that several months elapse before another VLCD phase is instituted [50]. Although lean tissue is lost on most weight reduction diets, this is a particular risk on VLCD, since greater energy restrictions are associated with more lean tissue losses [33].
The VLCD induces semi-starvation, which has both benefits and risks to the patient. Occasionally, with inadequate commercial products, such as one sold in the 1970’s that consisted of hydrolyzed collagen (an incomplete protein) with inadequate amounts of electrolytes, vitamins and minerals, deaths occurred [51]. Today commercial products are better regulated and are nutritionally complete by law. However, they can still be misused.
Some physiological effects are inevitable on VLCD. Mild ketosis occurs and increases risks of dehydration, although this can be avoided by ample fluid intake. Electrolyte imbalances may occur, and so may nutrient deficiencies if measures are not taken to prevent them on "home made" VLCD by use of appropriate supplements. Minor physiological problems that occur even with appropriate physician monitoring of cardiac and general health status include fatigue, dizziness (due to orthostatic hypotension), muscle cramps, gastrointestinal distress, and cold intolerance. The risk of cholelithiasis (gallstones) is increased, and seems to be particularly high when weight loss is very rapid (e.g. >1.5 kg/week). The risk of cholelithiasis can be decreased by administering ursodeoxycholic acid, including a moderate amount of fat in the diet, and limiting the amount of weight loss to 1.5kg per week [49].
Because these VLCD are so low in energy, they usually produce a greater initial weight loss than LCD. Patients who completed a comprehensive VLCD program including lifestyle modification lost an average of 15%-25% of initial weight within 3-4 months [49]. However, in comparisons of VLCD with energy levels of approximately 800 Calories versus diets at lower caloric levels of 400-500 Calories the lower VLCD did not necessarily result in greater weight loss, perhaps because compensatory reductions in resting energy expenditure, discretionary physical activity, and the lack of adherence on the lower calorie regimes thwarted weight loss [52]. There seems to be little difference in outcomes between commercial and homemade VLCD. The NIH expert panel review of existing studies found that preservation of weight loss over the long-term (e.g.>1 year) was not different on VLCD from that of LCD since most patients gained back 30%-50% of the lost weight. Therefore, the long-term advantage of VLCD in weight control is unclear.
Fasting is contraindicated for weight reduction because it causes excessive breakdown of lean tissue and ketosis. Also, the compensatory decreases in resting metabolism and physical activity on total fasts are profound and counterproductive since they lower energy output [1, 3].
The composition of the reducing diet influences the composition of the weight that is lost and nutritional status, and therefore it is also important. Several overviews of some popular diets and of the basic principles that must be considered in weight control provide more information [32, 41, 47, 53].
Dietary composition on reducing diets should be geared to decreasing risks of nutrient inadequacy and diet-related chronic diseases, particularly cardiovascular disease. Accordingly, the diet should be adequate in nutrients, with ample intakes of vitamins and minerals, relatively low in fat, saturated fat, cholesterol and sodium, and high in both soluble and insoluble fiber [1]. Consumption of fruits, vegetables, whole grains, lean sources of protein and water should be encouraged, with emphasis on balance and moderation [17]. Diets that promote extreme restriction or unusually high intakes of any macronutrient or food should be limited to a short amount of time. Recommendations for healthful composition of weight reducing diets are outlined in the 2005 Dietary Guidelines for Americans (Table 1) and discussed further in this section.
The macronutrient composition of the diet does not appear to play a major role in overall weight loss. However, there is one exception. Over the short term, low carbohydrate diets are ketogenic and cause a greater loss of body water then than body fat (at least in the first few days on the diet). Water weight is regained when the diet ceases or carbohydrate levels increase. When any reducing diet is maintained over the long term, if it remains hypocaloric, it results in a loss of body fat.
Because there is currently so much interest in the macronutrient composition of reducing diets, the positive and negative aspects of the major variations are described below.
With respect to weight loss, overweight individuals who consume moderate-fat, balanced macronutrient weight loss diets (approximately 25% fat, 15% protein and 60% carbohydrate) lose weight because they consume fewer calories than they expend. There is some evidence that these "balanced deficit" diets may produce weight loss even when they are consumed ad-libitum, but more research is necessary on this point, since it may be that other factors, such as variety or caloric density are more important.
However, other diets also produce weight loss. Overweight people who consume low and very low fat diets lose weight, probably simply because they consume fewer calories. It is also possible that other lifestyle factors play a part in this weight loss, such as increased energy expenditure as well as decreased fat and decreased energy intake, or perhaps all of these maneuvers have some small effects [46, 54]. It is less certain whether overweight persons who self-select high fat, low carbohydrate reducing diets consume fewer calories and lose weight under free-living conditions, although under experimental conditions they do so.
Although very low carbohydrate diets are associated with more loss of weight initially (the first week or so) in the long term such diets at not more effective than more balanced deficit regimens [55]. Very low carbohydrate diets also tend to be very high in protein and low in fruits and vegetables. It is important that the low carbohydrate foods also be low in saturated fat and high in mono or polyunsaturated fats. The relative proportion and kinds of fat vary somewhat. An emphasis on protein from fish, chicken and other lower fat options is recommended. Avoidance of long lists of "good" and "bad" food items is advisable [56, 18].
Some dieters do better on a starter diet that is very structured and low in calories so that enough weight is lost which motivates the patient to lose more.
The nutritional adequacy of different calorie levels and macronutrient composition for weight loss and weight maintenance diets vary [56]. The lower the reducing diet is in calories and the more its composition differs from usual levels, the greater the risk of nutrient inadequacy. Moderate fat, balanced macronutrient reduction diets are nutritionally adequate for the most part. Very low fat diets tend to be deficient in vitamins E, B12, calcium, iron and zinc. High fat, low carbohydrate diets are nutritionally inadequate and require supplementation to make them nutritionally adequate in many nutrients [46, 57, 58]. Dietary supplements used on weight reduction diets should be within RDA levels and below upper safe limits.
The metabolic effects of various popular diets with respect to decreased blood pressure, blood lipid, blood sugar, and serum insulin improve with energy restriction and weight loss, regardless of the macronutrient composition of the diet. However, there are some differences. Moderate fat, balanced nutrient reduction diets lower low-density lipoprotein (LDL) cholesterol, normalize plasma triglycerides, and normalize ratios of HDL/total cholesterol. High fat, very low carbohydrate diets result in ketosis. Low and very low fat diets (e.g. 15-20% of calories) reduce low-density lipoprotein (LDL) cholesterol, and after a transient rise in triglycerides, may also decrease plasma triglyceride levels. Low carbohydrate diets (e.g. <100gm carbohydrate) that result in weight loss may also cause a decrease in blood lipids, decreased blood glucose and insulin level, and decreased blood pressure. However, they are often high in saturated fat, total fat and in dietary cholesterol and low in plant-based nutrients such as fiber and antioxidants. No data are available on their impacts on cardiovascular disease, diabetes, cancer, and other chronic diseases beyond two years, so their long-term use remains in question [59]. They have the disadvantage of increasing uric acid and thus the potential risk of gallstones. Moreover, they are ketogenic, and often cause signs and symptoms such as dizziness, halitosis, fatigue, weakness, hypotension and malaise.
The proponents of various popular reducing diets who write popular diet books each claim that their regimen is optimal for quality of life, but as yet there is little objective information on this point.
Hunger may vary on the different diets, and also from one individual to the next, but again little objective evidence is available for comparing different reducing diets. Many factors affect hunger, appetite and subsequent food intake, including interactions between physiological and non-physiological factors. Greater average weight losses have been reported for low carbohydrate diets. In some studies [46] a low carbohydrate diet provided a metabolic advantage, resulting in a larger weight loss. A review of studies in which 24-hour energy expenditure was measured did not support this theory. Schoeller and Buchholz speculate that a greater consumption of protein may increase satiety, which in turn results in better adherence to hypocaloric diets [58]. However, this also remains to be proven.
Long-term compliance is likely to be a function of psychological issues rather than macronutrient composition itself. At present little is known about the nutritional or other characteristics of diets that maximize adherence. It is likely that "one size does not fit all" in this respect.
The Recommended Dietary Allowance for protein is 0.8 gm/kg/day, but most Americans eat approximately 15% of their total caloric intakes from protein, or about 1.2 gm/kg/day. Protein requirements do not decline and may actually rise on hypocaloric diets, especially on VLCDs, when protein needs sharply increase above the levels needed in energy balance. This is because when energy intakes are insufficient, glucogenic amino acids are used to maintain blood glucose levels and other ketogenic amino acids must be used for energy, so overall protein requirements increase. Fortunately, the hormonal milieu in hypocaloric states spares nitrogen to some extent and causes preferential use of fat for energy. Inevitably as adipose tissue is mobilized some lean tissue is lost and consequently some nitrogen is also lost. Losses of water, calcium, phosphorus, potassium, and vitamins follow the loss of lean tissue. Excess losses of lean body mass can be hazardous, affecting cardiovascular function, exercise tolerance, and possibly immune responses, and thus should be avoided. As mentioned previously, excess loss of lean tissue can result from energy deficits that are too great [33]. As a rule of thumb, a minimum of 65 to 70 gm of protein is needed daily. On a VLCD, 1.5gm of high quality protein per kilogram of ideal body weight per body weight is desirable, with intakes no less than and preferably more than 65-70 gm daily. Intakes may need to be even higher if the dieter suffers from certain diseases or is physically stressed, since nitrogen losses may rise further in these states. On diets providing 600-1200 Calories per day, daily protein intake should be at least 1 gm per kg ideal body weight per day. Reducing diets over 1200 Calories per day should supply at least 0.8 gm per kg ideal body weight. Levels should remain this high after weight loss has stopped and maintenance has begun.
High protein reducing diets are those that provide more than 1.6gm/kg of desirable weight per day. Self-prescribed high protein reducing diets vary in their composition from about 28-65% of energy, providing 71-163 gm of protein per day. They are currently popular as a new strategy for losing weight. They are usually quite low in their carbohydrate content. Some are clearly ketogenic and severely limit carbohydrates to below 50gm per day. Examples include the Doctor’s Quick Weight Loss Diet [60] and Dr. Atkins’ Diet Revolution [61].
Other diets are extremely high in protein, very low in carbohydrate and ketogenic but also very high in fat, such as Protein Power [62]. Two other high protein diets with enough carbohydrate so that they are not likely to be ketogenic are The Zone [63] and Sugar Busters [64].
All of the high protein diets include elaborate instructions that prescribe strict, structured eating schedules, and involve limited food variety and dietary flexibility. The high protein diets that are ketogenic also induce quick initial weight loss because of their low caloric level, and their diuretic effect owing to glycogen depletion, sodium and water loss. They may also be associated with decreased appetite due to the high protein intake, since protein may show to be particularly satiating. Ketosis has long been said to reduce appetite, although not all data have supported this. Nonetheless, for some patients these constraints may help them to achieve and maintain low calorie intakes at least over the short run. A comparison of a low carbohydrate diet with a low fat diet in patients with severe obesity found that patients on the low carbohydrate diet lost more weight than patients on a calorie restricted, fat-restricted diet, and had greater improvement in insulin sensitivity and triglyceride levels [65]. A second study also found a similarly greater weight loss using a low carbohydrate diet without adverse effects on blood lipids, glucose, or insulin [63]. Both diets were associated with reduced caloric intake of course. Clinical trials [34] and reviews of weight loss literature [49] show that long term results of such diets are similar to results using diets with other macronutrient compositions.
Popular high protein reducing regimens are not risk-free. Many of these diets advocate very high intakes of protein from meat and other foods that are also often high in saturated fat, cholesterol and sodium while they are low in dietary fiber, antioxidants, potassium, calcium, and magnesium, potentially increasing cardiovascular risk. The purine content of meat, poultry, seafood, egg, seeds, and nuts is high and increases uric acid levels and risk of gout in susceptible persons. The high protein load may increase urinary calcium loss if it is not buffered [66]. In patients with diabetic nephropathy, very high protein diets may speed progression, although the data are not definitive [67]. The extremely low carbohydrate intakes some very high protein diets also increase ketosis. Finally, and perhaps most important, there is no objective evidence to indicate that these diets promote greater weight loss or that the weight loss is better sustained. There is only one study of ad-libitum diets and nonfat loss that suggests the effects may not have been due to other non-controlled factors in the regimens studied, rather than to the protein [66]. For these and other reasons, the American Heart Association does not recommend high protein diets, and cautions that if they are used at all, they be limited for a short period of time [68, 69].
Even on reducing diets, the human body needs small amounts (e.g. 3-6gm) of essential fatty acids (linoleic or arachidonic acid). Some fat is also necessary as a carrier for the fat-soluble vitamins A, D, E, and K. Therefore the diet should not be devoid of fat. However, because fat is calorically dense, it is usually decreased on reducing diets to reduce energy intake while increasing bulk.
In general, levels of dietary fat, saturated fat, trans fat, polyunsaturated fat, monounsaturated fat, and cholesterol should follow guidelines from the American Heart Association on weight reduction diets. While lower levels may be appropriate in some cases, these levels amply meet requirements while supporting cardiovascular health [1].
Weight reduction diets that are moderate to low in fat (20-30% calories) are called "balanced deficit" because they maintain a reasonable balance between macronutrients similar to that recommended in MyPyramid.gov, DASH, and the Dietary Guidelines for Americans [11]. They tend to achieve most of the caloric deficit by reducing fat from the typical level in North American Diets of about 34% or more of calories to 20-30% fat, 15% protein, and 55-65% of calories from carbohydrates. Some examples of balanced deficit diets are the Weight Watchers Diet (25% fat, 20% protein, and 55% carbohydrate, with 26 gm dietary fiber), Jenny Craig, the National Cholesterol Education Program Step 1 diet (25% fat), diets based on the Food Pyramid, the DASH diet, the Shape up and Drop 10 diet of Shape Up! America [17], and the Nutrisystem diet. These dietary patterns have been extensively reviewed and appear to be optimal for weight reduction on low calorie diets for most individuals.
Very low fat diets such as the Pritikin diet [70] and the Ornish Diet [71] are advocated not only for weight reduction but also for improving cardiovascular risk profiles. The Ornish Diet, which is very low in fat (13% of calories) and saturated fat, very high in carbohydrate (81% of calories) and very high in fiber (38gm), is part of a program that includes nonsmoking, exercise and behavior modification. It was shown to reduce some cardiovascular risk factors in a limited long term study [71]. For those who can adhere to the Ornish regime it may be helpful.
High fat reducing diets are also usually low or very low in carbohydrate (<200 gm carbohydrate per day). Some current examples include Dr. Atkins’ Diet Revolution [61], Protein Power [62], the Carbohydrate Addicts Diet [72], Dr. Bernstein’s Diabetes Solution [73], Life Without Bread [74], and the Pennington Diet [75]. There is some evidence that free-living overweight people who self-select high fat, low carbohydrate diets that they eat ad-libitum consume fewer calories and lose weight [47]. This is not because the laws of thermodynamics are violated, but because there is so little to eat on such distorted regimens. When high fat, low carbohydrate reducing diets are fed they also tend to cause ketosis and diuresis. They may also result in decreased blood lipids, decreased blood glucose and insulin and decreased blood pressure, but only if weight is lost. Over the short term (a few days or a week) high fat, low carbohydrate, ketogenic diets cause a greater loss of body water than body fat, but water balance is quickly restored when carbohydrate levels increase or when the diet ends. High fat, low carbohydrate diets are often nutritionally inadequate and require some supplementation with micronutrients. If such high fat levels are continued on a chronic basis after weight is lost, they are likely to increase dietary risks for coronary artery disease.
Carbohydrate needs are at least 50 gm per day. At least 100 gm carbohydrate and preferably carbohydrate within the Acceptable Macronutrient Distribution Ranges of 45-65% of total energy intake should be provided for diets that are over 800 Calories per day. Under experimental conditions, both diets very high in sugars (mono-and di-saccharides) and diets very high in starches (digestible polysaccharides) that are equal in calories have similar effects in bringing about weight loss [76, 77]. However, from the practical standpoint, since many products that are high in sugar are calorically dense and often are also high in added fat and calories, and often low in fiber, vitamins and minerals sugars are usually limited on reducing diets.
Diets providing under 100 gm carbohydrates per day and especially those with 50 gm carbohydrates per day are ketogenic. Ketosis can be a problem on some popular diets a that are very low in carbohydrates, such as Dr. Atkins’ Diet Revolution [61], Protein Power [62], the Carbohydrate Addicts Diet [72], Dr. Bernstein’s Diabetes Solution [73], Life Without Bread [74], and the Pennington Diet [75]. Also, VLCDs containing fewer than 100 gm per day are ketogenic and may lead to excessive protein breakdown to maintain blood glucose levels unless protein intakes are increased. When the body must rely on degradation of protein’s carbon skeletons to preserve blood glucose levels via gluconeogenesis, the catabolism of the protein is accompanied by loss of water. For every gram of protein (or glycogen) that is broken down, 3 grams of water are released, causing rapid weight loss but also a state of relative dehydration [45]. Relative dehydration caused by ketosis and failure to drink adequate amounts of fluids is not only undesirable for health reasons, it reduces exercise tolerance [28]. It also does not address the primary purpose of the weight-reducing strategy, which is to decrease excess adipose tissue and not water weight.
The Glycemic Index (GI) is a dietary concept, originally developed for the therapy of diabetes, which has recently become popular in weight management. The GI is a property that describes the blood glucose response resulting from consumption of a defined amount of carbohydrate (usually 50 grams) from a given food, relative to the same amount of carbohydrate from a control food (usually white bread) [78]. The basic premise is that more moderate blood glucose and metabolic responses will sustain satiety and energy balance to a greater extent than would larger metabolic shifts over the course of the day. One example of such a diet is "Sugar Busters", a popular book that advocates the use of a low GI, high fiber, and high protein diet in weight reduction [64]. The problem is that the regimen is low in a number of nutrients and includes many odd recommendations of questionable utility (e.g. not eating fruit with meals) and it is also inadequate in several nutrients (calcium, vitamin D, Vitamin E, pantothenic acid, copper, and potassium). Moreover, no evidence of its efficacy is available. Most of the research on low GI diets in weight reduction has been conducted over relatively short time periods of a few days or weeks or is correlational. Although some data support low GI diets in preventing or treating obesity [79], the usefulness and applicability of such diets has been questioned [80]. The effects of low GI carbohydrates may help to prevent excess weight gain, but before low GI diets can be advocated as a weight-loss strategy, more research must be done on their longer-term efficacy [81, 79, 80]. However, consumption of whole grain cereals, legumes and whole foods which are low in GI, is helpful in meeting fiber goals as well and may be helpful in weight management diets. A well balanced, hypocaloric low glycemic index diet may prove to be effective in properly educated, adherent patients who do not misuse it by consuming excess fat or protein, or by completely excluding healthful high glycemic foods. For example, sausages, ice cream, and chocolate cake with frosting are all low GI foods, while parsnips, carrots, bananas, dates and potatoes are high GI foods. This underscores the point that more than just GI must be considered in food choices. It is still unclear if the glycemic index offers sustained advantages to patients in planning menus and in learning to control food intake compared to other weight reduction methods especially since GI is not listed on most food labels, and many factors influence it, such as cooking, ripeness, and the other foods consumed at the same meal. Any reducing diet must be viewed as a whole. Focusing on only one aspect whether is the glycemic index; the sugar content, carbohydrate, fiber, protein or fat is not a solution in itself.
Ample fluid intake is extremely important on weight reduction diets to avoid dehydration, especially if diets are ketogenic, very low in calories, or being undertaken in hot climates or with physical exertion. As mentioned earlier, losses of body glycogen and protein are accompanied by losses of body water. Intake of low-calorie or calorie-free fluids such as water should be emphasized [82]. Water needs go up with increases in physical activity, not only due to sweat losses, but also due to increased water losses due to aspiration [28]. The fatigue that some dieters associate with hypocaloric diets is often due in part to dehydration, especially if they have also increased their physical activity and exercise regimes dramatically. Body water losses of as little as 2% have been associated with decreased physical and mental performance, and impaired thermoregulation [82]. General water recommendations average approximately 2.7 liters (91 ounces) per day for women and 3.7 liters (125 ounces) per day for men. This includes total water intake from all beverages and water in foods. It has been estimated that 20% of total water consumption comes from solid foods [83]. A fluid intake plan should be incorporated in every weight loss regimen.
Under normal circumstances on a well-balanced diet that is not overly restrictive with energy, electrolyte balance is maintained. If an individual may be losing excess electrolytes due to high sweat losses, electrolytes can usually be replaced with normal foods [28]. The American diet is overly abundant in sodium, and potassium can be obtained in fruits and vegetables. Examples of foods that are high in both sodium and potassium include tomato sauces and vegetable soups. Most often, Americans tend to get too much sodium and insufficient potassium.
Electrolyte levels are of particular concern on VLCD, since occasionally cardiac arrhythmias have resulted from hypokalemia on such regimens [49]. Since hypokalemia can be fatal, electrolyte levels must always be monitored on VLCD.
Vitamin and mineral nutrition is critical during weight reduction and maintenance. The Recommended Dietary Allowance (RDA) for an individual’s age and sex must continue to be met even on reducing diets for all other nutrients (See Table 9). The lower the diet is in calories, the more likely it is that essential vitamins, minerals and electrolytes such as potassium, copper, magnesium, Vitamin E, Vitamin B6, folic acid, iron, and calcium are likely to be low. As a rule of thumb, diets below 1200 Calories per day are likely to require vitamin and mineral supplements in amounts approximating the Recommended Dietary Allowances [11]. Above 1200 Calories per day, women in reproductive age groups may still need iron, calcium and folic acid supplements since their needs for these nutrients are high, but most other nutrient needs can be met by a well-balanced diet that follows the Dietary Guidelines for Americans [11]. For this reason, foods with high micronutrient density, but low energy density are especially important to important to include on a reducing diet. They include fruits, vegetables, legumes, and lightly processed whole grains. Tables 9, 10, and 11 present current RDA’s for vitamins, minerals and tolerable upper levels (UL) for these same nutrients.
|
Table
9. Dietary Reference Intakes (DRIs): Recommended Intakes for
Individuals, Vitamins [84]
Food and Nutrition Board, Institute of Medicine, The National Academies |
||||||||||||||
|
Life Stage |
Vitamin A |
Vitamin C |
Vitamin D |
Vitamin E |
Vitamin K |
Thiamin |
Riboflavin |
Niacin |
Vitamin B6 |
Folate |
Vitamin B12 |
Pantothenic |
Biotin |
Choline |
|
Group |
(µg/d)a |
(mg/d) |
(µg/d)b,c |
(mg/d) d |
(µg/d) |
(mg/d) |
(mg/d) |
(mg/d)e |
(mg/d) |
(µg/d)f |
(µg/d) |
Acid (mg/d) |
(µg/d) |
(mg/d)g |
|
Infants 0–6 mo |
400* |
40* |
5* |
4* |
2.0* |
0.2* |
0.3* |
2* |
0.1* |
65* |
0.4* |
1.7* |
5* |
125* |
|
7–12 mo |
500* |
50* |
5* |
5* |
2.5* |
0.3* |
0.4* |
4* |
0.3* |
80* |
0.5* |
1.8* |
6* |
150* |
|
Children 1–3 y |
300 |
15 |
5* |
6 |
30* |
0.5 |
0.5 |
6 |
0.5 |
150 |
0.9 |
2* |
8* |
200* |
|
4–8 y |
400 |
25 |
5* |
7 |
55* |
0.6 |
0.6 |
8 |
0.6 |
200 |
1.2 |
3* |
12* |
250* |
|
Males 9–13 y |
600 |
45 |
5* |
11 |
60* |
0.9 |
0.9 |
12 |
1.0 |
300 |
1.8 |
4* |
20* |
375* |
|
14–18 y |
900 |
75 |
5* |
15 |
75* |
1.2 |
1.3 |
16 |
1.3 |
400 |
2.4 |
5* |
25* |
550* |
|
19–30 y |
900 |
90 |
5* |
15 |
120* |
1.2 |
1.3 |
16 |
1.3 |
400 |
2.4 |
5* |
30* |
550* |
|
31–50 y |
900 |
90 |
5* |
15 |
120* |
1.2 |
1.3 |
16 |
1.3 |
400 |
2.4 |
5* |
30* |
550* |
|
51–70 y |
900 |
90 |
10* |
15 |
120* |
1.2 |
1.3 |
16 |
1.7 |
400 |
2.4h |
5* |
30* |
550* |
|
> 70 y |
900 |
90 |
15* |
15 |
120* |
1.2 |
1.3 |
16 |
1.7 |
400 |
2.4h |
5* |
30* |
550* |
|
Females 9–13 y |
600 |
45 |
5* |
11 |
60* |
0.9 |
0.9 |
12 |
1.0 |
300 |
1.8 |
4* |
20* |
375* |
|
14–18 y |
700 |
65 |
5* |
15 |
75* |
1.0 |
1.0 |
14 |
1.2 |
400i |
2.4 |
5* |
25* |
400* |
|
19–30 y |
700 |
75 |
5* |
15 |
90* |
1.1 |
1.1 |
14 |
1.3 |
400i |
2.4 |
5* |
30* |
425* |
|
31–50 y |
700 |
75 |
5* |
15 |
90* |
1.1 |
1.1 |
14 |
1.3 |
400i |
2.4 |
5* |
30* |
425* |
|
51–70 y |
700 |
75 |
10* |
15 |
90* |
1.1 |
1.1 |
14 |
1.5 |
400 |
2.4h |
5* |
30* |
425* |
|
> 70 y |
700 |
75 |
15* |
15 |
90* |
1.1 |
1.1 |
14 |
1.5 |
400 |
2.4h |
5* |
30* |
425* |
|
Pregnancy |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
750 |
80 |
5* |
15 |
75* |
1.4 |
1.4 |
18 |
1.9 |
600j |
2.6 |
6* |
30* |
450* |
|
19–30 y |
770 |
85 |
5* |
15 |
90* |
1.4 |
1.4 |
18 |
1.9 |
600j |
2.6 |
6* |
30* |
450* |
|
31–50 y |
770 |
85 |
5* |
15 |
90* |
1.4 |
1.4 |
18 |
1.9 |
600j |
2.6 |
6* |
30* |
450* |
|
Lactation |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
1,200 |
115 |
5* |
19 |
75* |
1.4 |
1.6 |
17 |
2.0 |
500 |
2.8 |
7* |
35* |
550* |
|
19–30 y |
1,300 |
120 |
5* |
19 |
90* |
1.4 |
1.6 |
17 |
2.0 |
500 |
2.8 |
7* |
35* |
550* |
|
31–50 y |
1,300 |
120 |
5* |
19 |
90* |
1.4 |
1.6 |
17 |
2.0 |
500 |
2.8 |
7* |
35* |
550* |
|
NOTE: This table (taken from the DRI reports, see www.nap.edu) presents Recommended Dietary Allowances (RDAs) in bold type and Adequate Intakes (AIs) in ordinary type followed by an asterisk (*). RDAs and AIs may both be used as goals for individual intake. RDAs are set to meet the needs of almost all (97 to 98 percent) individuals in a group. For healthy breastfed infants, the AI is the mean intake. The AI for other life stage and gender groups is believed to cover needs of all individuals in the group, but lack of data or uncertainty in the data prevent being able to specify with confidence the percentage of individuals covered by this intake.
a As retinol activity equivalents (RAEs). 1 RAE = 1 µg retinol, 12 µg ß-carotene, 24 µg ∂-carotene, or 24 µg ß-cryptoxanthin. To calculate RAEs from REs of provitamin A carotenoids in foods, divide the REs by 2. For preformed vitamin A in foods or supplements and for provitamin A carotenoids in supplements, 1 RE = 1 RAE. b calciferol. 1 µg calciferol = 40 IU vitamin D. c In the absence of adequate exposure to sunlight. d As ∂-tocopherol. ∂-Tocopherol includes RRR-∂-tocopherol, the only form of ∂-tocopherol that occurs naturally in foods, and the 2R-stereoisomeric forms of ∂-tocopherol (RRR-, RSR-, RRS-, and RSS-∂-tocopherol) that occur in fortified foods and supplements. It does not include the 2S-stereoisomeric forms of ∂-tocopherol (SRR-, SSR-, SRS-, and SSS-∂-tocopherol), also found in fortified foods and supplements. e As niacin equivalents (NE). 1 mg of niacin = 60 mg of tryptophan; 0–6 months = preformed niacin (not NE). f As dietary folate equivalents (DFE). 1 DFE = 1 µg food folate = 0.6 µg of folic acid from fortified food or as a supplement consumed with food = 0.5 µg of a supplement taken on an empty stomach. g Although AIs have been set for choline, there are few data to assess whether a dietary supply of choline is needed at all stages of the life cycle, and it may be that the choline requirement can be met by endogenous synthesis at some of these s h Because 10 to 30 percent of older people may malabsorb food-bound B12, it is advisable for those older than 50 years to meet their RDA mainly by consuming foods fortified with B12 or a supplement containing B12. i In view of evidence linking folate intake with neural tube defects in the fetus, it is recommended that all women capable of becoming pregnant consume 400 µg from supplements or fortified foods in addition to intake of food folate from a varied diet. j It is assumed that women will continue consuming 400 µg from supplements or fortified food until their pregnancy is confirmed and they enter prenatal care, which ordinarily occurs after the end of the periconceptional period—the critical time for formation of the neural tube.
Copyright 2001 by the National Academy of Sciences. All rights reserved. 2/15/01 |
||||||||||||||
|
Table 10. Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals, Elements [84] Food and Nutrition Board, Institute of Medicine, National Academies |
||||||||||||
|
Life Stage |
Calcium |
Chromium |
Copper |
Fluoride |
Iodine |
Iron |
Magnesium |
Manganese |
Molybdenum |
Phosphorus |
Selenium |
Zinc |
|
Group |
(mg/d) |
(µg/d) |
(µg/d) |
(mg/d) |
(µg/d) |
(mg/d) |
(mg/d) |
(mg/d) |
(µg/d) |
(mg/d) |
(µg/d) |
(mg/d) |
|
Infants 0–6 mo |
210* |
0.2* |
200* |
0.01* |
110* |
0.27* |
30* |
0.003* |
2* |
100* |
15* |
2* |
|
7–12 mo |
270* |
5.5* |
220* |
0.5* |
130* |
11 |
75* |
0.6* |
3* |
275* |
20* |
3 |
|
Children 1–3 y |
500* |
11* |
340 |
0.7* |
90 |
7 |
80 |
1.2* |
17 |
460 |
20 |
3 |
|
4–8 y |
800* |
15* |
440 |
1* |
90 |
10 |
130 |
1.5* |
22 |
500 |
30 |
5 |
|
Males 9–13 y |
1,300* |
25* |
700 |
2* |
120 |
8 |
240 |
1.9* |
34 |
1,250 |
40 |
8 |
|
14–18 y |
1,300* |
35* |
890 |
3* |
150 |
11 |
410 |
2.2* |
43 |
1,250 |
55 |
11 |
|
19–30 y |
1,000* |
35* |
900 |
4* |
150 |
8 |
400 |
2.3* |
45 |
700 |
55 |
11 |
|
31–50 y |
1,000* |
35* |
900 |
4* |
150 |
8 |
420 |
2.3* |
45 |
700 |
55 |
11 |
|
51–70 y |
1,200* |
30* |
900 |
4* |
150 |
8 |
420 |
2.3* |
45 |
700 |
55 |
11 |
|
> 70 y |
1,200* |
30* |
900 |
4* |
150 |
8 |
420 |
2.3* |
45 |
700 |
55 |
11 |
|
Females 9–13 y |
1,300* |
21* |
700 |
2* |
120 |
8 |
240 |
1.6* |
34 |
1,250 |
40 |
8 |
|
14–18 y |
1,300* |
24* |
890 |
3* |
150 |
15 |
360 |
1.6* |
43 |
1,250 |
55 |
9 |
|
19–30 y |
1,000* |
25* |
900 |
3* |
150 |
18 |
310 |
1.8* |
45 |
700 |
55 |
8 |
|
31–50 y |
1,000* |
25* |
900 |
3* |
150 |
18 |
320 |
1.8* |
45 |
700 |
55 |
8 |
|
51–70 y |
1,200* |
20* |
900 |
3* |
150 |
8 |
320 |
1.8* |
45 |
700 |
55 |
8 |
|
> 70 y |
1,200* |
20* |
900 |
3* |
150 |
8 |
320 |
1.8* |
45 |
700 |
55 |
8 |
|
Pregnancy |
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
1,300* |
29* |
1,000 |
3* |
220 |
27 |
400 |
2.0* |
50 |
1,250 |
60 |
12 |
|
19–30 y |
1,000* |
30* |
1,000 |
3* |
220 |
27 |
350 |
2.0* |
50 |
700 |
60 |
11 |
|
31–50 y |
1,000* |
30* |
1,000 |
3* |
220 |
27 |
360 |
2.0* |
50 |
700 |
60 |
11 |
|
Lactation |
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
1,300* |
44* |
1,300 |
3* |
290 |
10 |
360 |
2.6* |
50 |
1,250 |
70 |
13 |
|
19–30 y |
1,000* |
45* |
1,300 |
3* |
290 |
9 |
310 |
2.6* |
50 |
700 |
70 |
12 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
31–50 y |
1,000* |
45* |
1,300 |
3* |
290 |
9 |
320 |
2.6* |
50 |
700 |
70 |
12 |
|
NOTE: This table presents Recommended Dietary Allowances (RDAs) in bold type and Adequate Intakes (AIs) in ordinary type followed by an asterisk (*). RDAs and AIs may both be used as goals for individual intake. RDAs are set to meet the needs of almost all (97 to 98 percent) individuals in a group. For healthy breastfed infants, the AI is the mean intake. The AI for other life stage and gender groups is believed to cover needs of all individuals in the group, but lack of data or uncertainty in the data prevent being able to specify with confidence the percentage of individuals covered by this intake.
Copyright 2001 by the National Academy of Sciences. All rights reserved. 2/15/01 |
||||||||||||
|
Table 11. Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels (ULa) , Vitamins [84] Food and Nutrition Board, Institute of Medicine, National Academies |
|||||||||||||||
|
Life Stage Group |
Vitamin A (µg/d)b |
Vitamin C (mg/d) |
Vitamin D (µg/d) |
Vitamin E (mg/d)c,d |
Vitamin K |
Thiamin |
Ribo-flavin |
Niacin (mg/d)d |
Vitamin B6 (mg/d) |
Folate (µg/d)d |
Vitamin B12 |
Pantothenic Acid |
Biotin |
Choline (g/d) |
Carote-noidse |
|
Infants |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0-6 mo |
600 |
NDf |
25 |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
|
7-12 mo |
600 |
ND |
25 |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
ND |
|
Children |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1-3 y |
600 |
400 |
50 |
200 |
ND |
ND |
ND |
10 |
30 |
300 |
ND |
ND |
ND |
1.0 |
ND |
|
4-8 y |
900 |
650 |
50 |
300 |
ND |
ND |
ND |
15 |
40 |
400 |
ND |
ND |
ND |
1.0 |
ND |
|
Males, Females |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
9-13 y |
1,700 |
1,200 |
50 |
600 |
ND |
ND |
ND |
20 |
60 |
600 |
ND |
ND |
ND |
2.0 |
ND |
|
14-18 y |
2,800 |
1,800 |
50 |
800 |
ND |
ND |
ND |
30 |
80 |
800 |
ND |
ND |
ND |
3.0 |
ND |
|
19-70 y |
3,000 |
2,000 |
50 |
1,000 |
ND |
ND |
ND |
35 |
100 |
1,000 |
ND |
ND |
ND |
3.5 |
ND |
|
> 70 y |
3,000 |
2,000 |
50 |
1,000 |
ND |
ND |
ND |
35 |
100 |
1,000 |
ND |
ND |
ND |
3.5 |
ND |
|
Pregnancy |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
2,800 |
1,800 |
50 |
800 |
ND |
ND |
ND |
30 |
80 |
800 |
ND |
ND |
ND |
3.0 |
ND |
|
19-50 y |
3,000 |
2,000 |
50 |
1,000 |
ND |
ND |
ND |
35 |
100 |
1,000 |
ND |
ND |
ND |
3.5 |
ND |
|
Lactation |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
2,800 |
1,800 |
50 |
800 |
ND |
ND |
ND |
30 |
80 |
800 |
ND |
ND |
ND |
3.0 |
ND |
|
19-50 y |
3,000 |
2,000 |
50 |
1,000 |
ND |
ND |
ND |
35 |
100 |
1,000 |
ND |
ND |
ND |
3.5 |
ND |
|
a UL = The maximum level of daily nutrient intake that is likely to pose no risk of adverse effects. Unless otherwise specified, the UL represents total intake from food, water, and supplements. Due to lack of suitable data, ULs could not be established for vitamin K, thiamin, riboflavin, vitamin B12, pantothenic acid, biotin, or carotenoids. In the absence of ULs, extra caution may be warranted in consuming levels above recommended intakes. b As preformed vitamin A only. c As ∂-tocopherol; applies to any form of supplemental ∂-tocopherol. d The ULs for vitamin E, niacin, and folate apply to synthetic forms obtained from supplements, fortified foods, or a combination of the two. e ß-Carotene supplements are advised only to serve as a provitamin A source for individuals at risk of vitamin A deficiency. f ND = Not determinable due to lack of data of adverse effects in this age group and concern with regard to lack of ability to handle excess amounts. Source of intake should be from food only to prevent high levels of intake.
SOURCES: Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride (1997); Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998); Dietary Reference Intakes for Vitamin C, Vitamine E, Selenium, and Carotenoids (2000); and Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001). These reports may be accessed via www.nap.edu. Copyright 2001 by the National Academy of Sciences. All rights reserved. 2/15/01 |
|||||||||||||||
|
Table 12. Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels (ULa), Elements [84] Food and Nutrition Board, Institute of Medicine, National Academies |
|||||||||||||||||
|
Life Stage Group |
Arsenicb |
Boron (mg/d) |
Calcium (g/d) |
Chrom-ium |
Copper (µg/d) |
Fluoride (mg/d) |
Iodine (µg/d) |
Iron (mg/d) |
Magnes-ium (mg/d)c |
Manga- nese (mg/d) |
Molyb-denum (µg/d) |
Nickel (mg/d) |
Phos-phorus (g/d) |
Selenium (µg/d) |
Silicond |
Vana-dium (mg/d)e |
Zinc (mg/d) |
|
Infants |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0-6 mo |
NDf |
ND |
ND |
ND |
ND |
0.7 |
ND |
40 |
ND |
ND |
ND |
ND |
ND |
45 |
ND |
ND |
4 |
|
7-12 mo |
ND |
ND |
ND |
ND |
ND |
0.9 |
ND |
40 |
ND |
ND |
ND |
ND |
ND |
60 |
ND |
ND |
5 |
|
Children |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1-3 y |
ND |
3 |
2.5 |
ND |
1,000 |
1.3 |
200 |
40 |
65 |
2 |
300 |
0.2 |
3 |
90 |
ND |
ND |
7 |
|
4-8 y |
ND |
6 |
2.5 |
ND |
3,000 |
2.2 |
300 |
40 |
110 |
3 |
600 |
0.3 |
3 |
150 |
ND |
ND |
12 |
|
Males, Females |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
9-13 y |
ND |
11 |
2.5 |
ND |
5,000 |
10 |
600 |
40 |
350 |
6 |
1,100 |
0.6 |
4 |
280 |
ND |
ND |
23 |
|
14-18 y |
ND |
17 |
2.5 |
ND |
8,000 |
10 |
900 |
45 |
350 |
9 |
1,700 |
1.0 |
4 |
400 |
ND |
ND |
34 |
|
19-70 y |
ND |
20 |
2.5 |
ND |
10,000 |
10 |
1,100 |
45 |
350 |
11 |
2,000 |
1.0 |
4 |
400 |
ND |
1.8 |
40 |
|
> 70 y |
ND |
20 |
2.5 |
ND |
10,000 |
10 |
1,100 |
45 |
350 |
11 |
2,000 |
1.0 |
3 |
400 |
ND |
1.8 |
40 |
|
Pregnancy |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
ND |
17 |
2.5 |
ND |
8,000 |
10 |
900 |
45 |
350 |
9 |
1,700 |
1.0 |
3.5 |
400 |
ND |
ND |
34 |
|
19-50 y |
ND |
20 |
2.5 |
ND |
10,000 |
10 |
1,100 |
45 |
350 |
11 |
2,000 |
1.0 |
3.5 |
400 |
ND |
ND |
40 |
|
Lactation |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
≤ 18 y |
ND |
17 |
2.5 |
ND |
8,000 |
10 |
900 |
45 |
350 |
9 |
1,700 |
1.0 |
4 |
400 |
ND |
ND |
34 |
|
19-50 y |
ND |
20 |
2.5 |
ND |
10,000 |
10 |
1,100 |
45 |
350 |
11 |
2,000 |
1.0 |
4 |
400 |
ND |
ND |
40 |
|
a UL = The maximum level of daily nutrient intake that is likely to pose no risk of adverse effects. Unless otherwise specified, the UL represents total intake from food, water, and supplements. Due to lack of suitable data, ULs could not be established for arsenic, chromium, and silicon. In the absence of ULs, extra caution may be warranted in consuming levels above recommended intakes. b Although the UL was not determined for arsenic, there is no justification for adding arsenic to food or supplements. c The ULs for magnesium represent intake from a pharmacological agent only and do not include intake from food and water. d Although silicon has not been shown to cause adverse effects in humans, there is no justification for adding silicon to supplements. e Although vanadium in food has not been shown to cause adverse effects in humans, there is no justification for adding vanadium to food and vanadium supplements should be used with caution. The UL is based on adverse effects in laboratory animals and this data could be used to set a UL for adults but not children and adolescents. f ND = Not determinable due to lack of data of adverse effects in this age group and concern with regard to lack of ability to handle excess amounts. Source of intake should be from food only to prevent high levels of intake.
SOURCES: Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride (1997); Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998); Dietary Reference Intakes for Vitamin C, Vitamine E, Selenium, and Carotenoids (2000); and Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001). These reports may be accessed via www.nap.edu. Copyright 2001 by the National Academy of Sciences. All rights reserved. 2/15/01 |
|||||||||||||||||
Some studies suggest that calcium supplementation and/or supplementation of dairy products in the diet play a direct role in the prevention and treatment of obesity. In normal weight adult females who are not on calorie reducing diets, dairy products and/or supplementation has little effect on weight [85]. However, in a 6 month follow-up, Egan reported a decreased body fat mass among such persons [88].
A systematic review and meta-analysis of randomized controlled trials studying the use of calcium supplementation or dairy products as interventions for weight loss by Trowmen et al found that only one study out of 13 studies showed that an association with weight loss [87]. However, Zemel concluded that calcium supplementation or dairy products as interventions for weight loss are effective [88]. In the systemic review, flaws in study designs were noticed. More studies suggested that there might be a beneficial effect than did not. Therefore, more research is necessary to rule out or in the effects of calcium and/or dairy supplementation on weight loss. A large NIH sponsored clinical trial should be published shortly.
Major et al recently found that calcium plus vitamin D supplementation enhanced the beneficial effect on the lipid profile with weight loss. However, it had no effect on weight [89]. There is also some evidence that high calcium or high dairy intakes during weight loss spare lean body loss to a greater extent than lower levels.
Another study by Thompson recently found no evidence that diets providing more then 800mg of calcium in dairy products or those higher in fiber and lower in glycemic index enhanced weight reduction beyond what was seen with calorie restriction alone [90].
Ephedra, or Ma Huang, is the common name for an herb used in traditional Chinese Medicine (TCM). Its use for weight reduction is not a common practice in TCM. Greenway et al reported many years ago that caffeine and Ephedra in combination resulted in a 7.3% to 7.8% weight loss. However, it was a small study with only 12 people. No adverse side effects were reported. Americans used this supplement as a weight loss aid from the mid 1990’s to 2004 when it was banned by the FDA [91,92].
The NIH sponsored a thorough systematic review of the safety and efficacy of Ephedra through the Agency of Healthcare Research and Quality’s (AHRQ) Evidence Based Practice Center at the University of Southern California, which conducted the study. It concluded that the use of Ephedra with or without caffeine correlated with a small but nonetheless statistically significant increase in weight loss over six months, (almost equal to 0.9 kg/month more than the placebo). The weight lost by those taking Ephedra in combination with caffeine exceeded weight lost by prescription medications in two head-to-head randomized, double-blinded clinical trials [91]. There were no studies that measured the long-term effects (more than 6 months) of ephedra use. Adverse effects of the supplement in the AHRQ study included two to three times more nausea, vomiting, psychiatric symptoms such as anxiety and change in mood, autonomic hyperactivity, and palpitations when compared with placebo. Serious adverse events (SAE’s) were defined as specified by FDA criteria. SAEs were reported to the FDA, and adverse event reports from a manufacturer of Ephedra-containing dietary supplements were also evaluated in the RAND/Southern California systemic review. These reports raised concern about the safety of dietary supplements containing Ephedra due to the number of deaths, myocardial infarctions, cerebrovascular accidents, seizures, and serious psychiatric illnesses in young adults, data was sufficient to warrant concern [91].
The FDA concluded in 2004 that Ephedra-containing products were not to be recommended for weight loss. There was unreasonable risk for illness and injury when taking such dietary supplements. Thus, the sale of dietary supplements containing Ephedra has been prohibited in the United States since April 2004 [91]. Ephedra like supplements such as Citrus autrantium may also pose risk. The latest information on dietary supplements and weight loss can be found at www.ods.nih.gov.
Dietary fiber is chemically similar to carbohydrate in most of its forms but it is virtually non-caloric because the human body lacks the enzymes to break the glycosidic bonds in the fiber. Some short-term primary weight gain intervention studies, and cross sectional studies show that an increased dietary fiber intake can reduce the likelihood of weight gain. However, research has not proven that fiber is effective as a weight loss aid [93]. It should be included in the LCD reducing diet at levels of about 20-35 gm per day if for nothing else than to facilitate normal laxation. Both soluble and insoluble dietary fiber may also modify hunger and help to sustain internal satiety, but again experimental studies are not conclusive [94, 95, 6]. Inclusion of five or more servings of fruits and vegetables daily, with plenty of whole grain breads and cereals can help to meet the goal of obtaining both soluble and insoluble fiber on the reducing diet. On a VLCD, it is also important to include at least some fiber. As dietary fiber intake increases, water requirements also increase, and intakes of fluid should also be substantial. Adequate fiber and water are essential for maintaining the softness of the stool and normal laxation. Furthermore, ample fiber intakes are associated with reduced risk for several chronic diseases [96].
Alcohol (ethanol) contains approximately 7 Calories per gram, providing more energy per unit of weight than either carbohydrate or protein (each ~4 Calories/gm), but less than fat (~9 Calories/gm). Alcoholic beverages tend to be a source of non-nutritive energy, or "empty calories". If protein, carbohydrate and/or fat are consumed at the same time as alcohol is ingested, their oxidation will be suppressed (most notably fat oxidation), since alcohol is preferentially oxidized, and the other macronutrients balance through the sparing effect of alcohol on fat oxidation, leading to increased fat storage. Chronic overconsumption of alcohol can lead to fatty liver and dyslipidemia and weight gain.
Another important consideration concerning alcohol’s influence on energy balance is its effects on energy intake. Alcohol is positioned at the bottom of the hierarchy of satiating efficiency of metabolic fuels consumed by humans [6]. Generally, it is accepted that the fuels satiate to degrees from lowest to highest: alcohol, fat, carbohydrate (depending on type), and protein [97]. Alcohol energy is additive to the diet, producing no compensation in energy intake under most ad-libitum situations, and in fact, alcohol may stimulate appetite [98, 99]. For these reasons, alcohol consumption is usually contraindicated on weight-loss diets.
Energy density is defined as the calories provided per unit weight of food eaten. A low energy density of foods in the diet appears to have effects on satiety and satiation that may aid in weight reduction [100]. When the composition of a diet of usual foods is decreased in fat, the energy density of the diet tends to fall since the total weight of food consumed remains constant [102, 103]. It is possible that some of the beneficial effects of low fat diets in weight loss and maintenance are due to low energy density rather than to fat itself. Furthermore, foods high in water and/or fibers tend to have low energy density, so their inclusion in a weight reduction diet may be advocated for this reason as well [6].
Many physicians lack the time that obese patients require for successful weight control therapy. Referral for dietary counseling to a registered dietitian (RD) is useful for many patients, particularly those who have comorbidities that also require medical nutrition therapy.
There are over 67,000 registered dietitians in the United States practicing in hospitals, health centers and the community. Registered dietitians accept patient referrals from physicians for a variety of health problems that require dietary modification. Some formal weight control programs staffed by dietitians are available in hospitals and health centers. Individual counseling is also available. The website for the American Dietetic Association can be accessed at www.eatright.org.
Dietary advice of a general nature is not enough for patients who have many comorbidities requiring medical nutrition therapy or other medical or surgical intervention, those on multiple medications, and those with complex and involved health problems that have dietary implications. These patients are prime candidates for dietetic therapy. Patients who have had poor outcomes in weight control efforts on their own, who have special dietary needs or preferences and who need extensive education and assistance are also particularly likely to benefit.
Registered dietitians are able to read and interpret medical records and are equipped to adopt weight loss prescriptions to the particular needs of patients. Their knowledge of food habits, food preparation, and food products on the market makes them a good resource for helping patients to adopt the general weight control prescription to the patient’s particular circumstances. A particular advantage of dietetic involvement in patient care is that dietitians often work in medical settings and have access to patient charts as well as to consultation with other health professionals. Registered dietitians are helpful for dealing with patients on multiple medication on very low caloric diets and post gastric bypass counseling. Some dietitians have advanced certification in weight management, and are especially well equipped to counsel patients with complex and involved medical problems. Some insurance companies and health maintenance organizations may pay for obesity treatment when it is part of a larger therapeutic program for diabetes or some other conditions if it involves a dietitian who is a certified Medicare provider.
The patient’s out-of-pocket costs for dietary counseling vary, depending on insurance coverage and comorbidities.
Registered dietitians are health professionals who are licensed in most states and who have medical, legal, and ethical obligations to their patients. They often have access to patient medical records. Their own education includes formal educational requirements of at least a baccalaureate degree, a dietetic internship, supervised clinical training, a registration exam, and mandatory continuing education. Dietitians are trained to be conservative and to alert physicians when untoward events arise. Thus their recommendations tend to be safe. The effectiveness of dietetic counseling, like that of physician counseling for weight control, has seldom been evaluated. The American Dietetic Association, the dietetic professional association, is currently developing and testing clinical guidelines for weight reduction and management of various obesity-related conditions.
Commercial non-medical weight control programs are popular and widely available in the United States and Canada.
Commercial programs include large chains such as Weight Watchers, Jenny Craig, LA Weight Loss, Curves, and many regional ventures. These programs vary, but generally include advice on a structured low calorie diet, exercise, lifestyle modification coupled with group support (Weight Watchers) and/or individual counseling (Jenny Craig). Usually the program is administered by a layperson trained by the program who is often a successful program graduate. All of these programs are for-profit entities and charge fees [102].
Moderately obese persons with few risk factors and co-morbidities are good candidates for these programs. Those who find that they need continued motivation, monitoring and social support with a structured regimen may particularly benefit from the program.
These programs are not substitutes for physician concern or monitoring of his or her patients’ weights. They are most successful when the physician continues to provide encouragement. The programs are not equipped to deal with patients with multiple involved comorbidities of a medical or psychological nature. Those patients are better treated by a program and therapists who are more closely connected to the health care system, such as registered dietitians or specialized weight control programs operated by medical facilities.
Most major chains offer well crafted, nutritionally adequate and behaviorally sound programs that are reasonable therapies. Classes are often held in places of employment or neighborhood centers that are conveniently located. Weight Watchers also offers frozen entrées and other weight control products that are keyed into the program and available in the supermarkets, making adherence easier.
Since 1997 most of the large commercial programs have joined the Partnership for Healthy Weight Management, a voluntary association. Members provide on a voluntary basis, publicly available information to help potential participants meet their needs. Criteria for membership require that programs disclose staff qualifications, essential components of the program, the risks associated with overweight and obesity, other details about the provider’s program or product, and program costs.
The main objective of a commercial weight loss programs is profit. Although physician approval is required by most programs before participants can enroll, there is no guarantee of the quality of the health assessment that has been carried out. For some individuals, especially those at very high risk, more intensive medical supervision may be required. The cost of the programs is another obstacle. Many of the poor who are obese do not have the resources to purchase these services and products, even though they might benefit from them. Discounts or waivers of fees for those in financial hardship are rarely available. The companies have become more active in developing programs catering to those who have lost weight to help them maintain their losses in recent years, but incentives for staying in maintenance programs may still not be sufficient.
The major firms provide a program and product, which are safe when directions are followed. However, in spite of the fact that millions of Americans have purchased these services, their effectiveness in bringing about weight loss or sustaining lower weights has rarely been studied with scientific rigor [49]. The only commercial weight loss program that has been evaluated by a large randomized controlled trial is Weight Watchers, and in that study, average weight reduction was 3.2% over a period of two years [49].
Many meal replacement and formula products for weight control are now available which patients can purchase on their own in supermarkets and drug stores. Unlike very low calorie diet formulas, which are medical foods that are usually provided as part of a medically supervised treatment program, such as HMR or Optifast, these products can be purchased by anyone.
Meal replacements now include not only powders like Slimfast that are mixed with milk or other liquids, but drinks, bars, and frozen entrees. Formulations and nutrient content vary. Most liquid meal replacement products provide about 220 Calories per serving and are relatively high in protein, vitamins and minerals but low in fat. The health bars and frozen entrees vary in their caloric content, but are generally between 200-400 Calories and have more complete profile of nutrients than most other single foods. The entrees, which include offerings such as "Lean Cuisine", "Healthy Choice", and "Smart Ones" (products geared to the Weight Watches program) all share characteristics such as discrete portion sizes that are relatively low in calories (usually 300 calories or less). Smart Ones is manufactured by HJ Heinz, and is closely allied with the Weight Watchers commercial diet program. Its packages are prepared to fit into the food plans for the Weight Watchers program. All of the meal replacement products are designed to be eaten with additions of conventional foods that supply dietary fiber, other nutrients, additional calories and fluids. The newest entries in this category are the South Beach Diet line of products that are produced by Kraft foods and the Atkins diet bars and entrees which are struggling, but still on the market under a private label.
Individuals who are healthy but moderately overweight (BMI 25-30) and who wish to lose less than 5% of their body weight or who wish to use these products for one meal a day to assist in their weight maintenance efforts may find these products helpful. The products provide an easily prepared, generally nutritious, and relatively modest caloric load that slakes hunger. For those who are susceptible to environmental triggers (such as being involved in meal preparation, eating in cafeterias or fast food restaurants) and respond by overeating, these products offer a safe and palatable option that lessens temptation.
Portion controlled liquid meal replacements such as Slim Fast (and many other products) are recommended for two meals and a snack with a small meal of conventional foods and low or no calorie beverages. They should not be used as the sole source of nourishment on a diet. The entrée choices are suitable for lunches or dinners.
The main advantages of meal replacements are built-in portion and Calorie control, widespread availability, convenience composition that is fairly micronutrient dense while remaining low in calories, ease of preparation, and for some of the dry or canned products portability. Also, costs of the meal replacements are reasonable and simplify food choice decisions. They are lower in calories than many snack foods that people who are eating away from home might substitute for them. Also, they are convenient, rapidly and easily prepared options that can be eaten anywhere, allowing eaters to avoid "high risk" eating environments.
The major disadvantages of these products are their cost, monotony, low taste, and limited variety. From the nutritional standpoint, the products vary but are often quite high in sodium. Only Healthy Choice is low in calories, saturated fat, and also in sodium. Perhaps their major disadvantage is that they are ineffective unless they are used as part of an overall low calorie eating plan. If they were used as sole sources of food and unsupplemented they would be nutritionally inadequate not only in energy but several other nutrients and water.
These products may be nutritionally inadequate when they are used as the sole sources of food and fluids. When the products are used according to directions on the label or in package inserts, they are safe [31]. When used as part of a weight loss program these single meal replacements are effective during the weight loss phase [103]. They are also valuable additions in the weight maintenance phase, often because the meal replacements provide a low set number of calories in an easy-to-fix-entrée [3, 97], with control over portion size [105].
Commercial catering operations in many parts of the country have begun to offer prepared, delivered meals directly to consumers and some internet sites that are appropriate for weight reduction programs. No large chain or franchise is currently providing such offerings nationwide. In the late 1980’s several major food companies attempted to provide a line of portion controlled meals that also incorporated nutrient profiles in line with the NIH’s National Cholesterol Education Project’s type 1 diet plan to assist individuals in controlling their weights and other chronic disease risk factors. For example, the Campbell Soup Company’s "Intelligent Cuisine" line provided prescribed, portion-controlled meals that also incorporated nutrient profiles in line with the NIH’s National Cholesterol Education Project’s type 1 diet plan to assist individuals in controlling their weights and other chronic disease risk factors. A portion controlled line of foods provided 1200-1400 Calories a day and were sent dieters directly by mail. The products were to be used with additional foods such as fruits and vegetables, salads, and fluids that the dieter supplied himself. Marketing was done not to patients directly, but to their physicians, who provided medical back up and additional reinforcement [106]. This marketing channel did not prove to be effective.
Evaluations of the IQ line were compared to self-selected diets of conventional foods after 2.5 months. Those on the portion controlled IQ diet had lost more weight (4.7 vs. 3.1 kg) than controls and a number of risk factors for chronic diseases were also decreased [107]. Unfortunately, in spite of these positive findings, the business plan was not successful and the products are no longer sold on the market.
In addition to weight loss products, Table 13 provides some examples of popular diet books. Books are difficult to use on one’s own because there is little reinforcement. The quality of self-help books on weight control ranges from the sublime to the ridiculous. Among the better books currently on the market are the LEARN Program for Weight Management, which is a sound 15 week course that is usually administered within a treatment program [108, 63]. The book is effective when it is part of the treatment program. However, the charges for such a program are considerable, the program is not available in all parts of the country, and the effectiveness of self directed efforts using the book by itself has not been evaluated. Another good book is Volumetrics by Barbara Rolls PhD [109], which encourages a diet based on foods that have a low energy density, meaning that they contain few calories per gram of weight. Dr. Rolls’ research has shown that foods with large volume but few calories can provide satiety while helping individuals avoid over-consumption of energy. Such foods are usually high in water and fiber, while low in fat. Although the long-term efficacy of this specific diet has yet to be affirmed, the diet is rich in fruits, vegetables, and other healthful foods [109].
|
Table 13. Brief Description of Popular Diet Programs and Books 27 |
||||||
|
Diet |
Brief description |
Average Calories Per Day |
Composition % of Calories |
Type of Diet |
||
|
|
|
|
%CHO |
%Protein |
%Fat |
|
|
|
|
|
|
|
|
|
|
Optifast |
Medically supervised liquid formula which also |
800 (first 12 weeks) |
52 |
29 |
19 |
Extremely low |
|
Novartis |
includes some commercial products like bars |
|
|
|
|
|
|
|
and soups |
1250 (weeks 12-18) |
|
|
|
Low Calorie |
|
Slimfast |
A commercial line of shakes, powders, and |
1800 |
69 |
18 |
13 |
Weight Maintenance |
|
Unilever |
bars that serve as meal replacements |
|
|
|
|
|
|
|
and/or snacks |
|
|
|
|
|
|
South Beach |
3 phase book by Arthur Agaston MD |
Phase 1: 1400 |
16 |
38 |
46 |
Low Calorie |
|
Diet |
|
|
|
|
|
|
|
|
|
Phase 2: 1390 |
37 |
26 |
40 |
Low Calorie |
|
|
|
|
|
|
|
|
|
|
|
Phase 3: 1500 |
31 |
29 |
40 |
Low Calorie |
|
|
|
|
|
|
|
|
|
The Ultimate |
Dr. Phil MrGraw authored this 3 phase |
Phase 1: 1300 |
47 |
36 |
17 |
Low Calorie |
|
Weight |
diet book |
|
|
|
|
|
|
Solution |
|
Phase 2: 1100 |
49 |
32 |
19 |
Very low calorie |
|
|
|
|
|
|
|
|
|
|
|
Phase 3: 1820 |
52 |
27 |
17 |
Weight Maintenance |
|
|
|
|
|
|
|
|
|
Atkins for Life |
A low carbohydrate plan for those who have |
Phase 1: 1540 |
24 |
21 |
55 |
Weight Maintenance |
|
|
lost weight with the original Atkins Diet. |
|
|
|
|
|
|
|
Dieters are advised to cut back on |
Phase 2: 1970 |
22 |
22 |
56 |
Weight Maintenance |
|
|
Carbohydrates if weight loss is suspended. |
|
|
|
|
|
|
|
|
Phase 3: 2310 |
29 |
19 |
52 |
Weight Maintenance |
|
|
|
Pre-Maintenance |
|
|
|
|
|
|
|
Phase 4: 2050 |
35 |
20 |
44 |
Weight Maintenance |
|
|
|
Lifetime Maintenance |
|
|
|
|
|
Body for Life |
This book focuses primarily on exercise |
1270 |
|
|
|
Low Calorie |
|
for Women |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The Abs Diet |
This diet is based on foundation foods that |
1700 |
45 |
25 |
30 |
Weight Maintenance |
|
|
conform to the acronym Abs Diet Power |
|
|
|
|
|
|
|
Almonds and other nuts, Beans and legumes, |
|
|
|
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Spinich and green vegetables, Dairy (fat free |
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or low fat), Instant Oatmeal, Eggs, |
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Turkey and lean meats, |
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Peanut butter (natural and sugar free) |
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Olive oil, Whole-grain breads and cereals, |
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Extra protein (whey powder), Raspberries and |
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other berries |
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French |
Lifestyle changes illustrated through an |
1200-1300 |
43 |
22 |
45 |
Low Calorie |
|
Women Don't |
autobiography of the author |
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Get Fat |
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Jenny Craig |
The keystone to Jenny Craig is its |
1200+ (individualized) |
50 |
25 |
25 |
Low Calorie |
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its prepackaged meals. For the most part |
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these are frozen breakfasts, lunches, dinners, |
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and desserts. Participants work with a |
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personal consultant |
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Weight |
Individually personalized for each client. |
1200+ (individualized) |
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Low Calorie |
|
Watchers |
Weight watchers has two plans, the points |
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plan and the no counting plan. Both plans |
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include weekly group meetings and weigh-ins. |
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Learn
|
Lifestyle, Exercise, Attitudes, Relationships |
1650 |
55 |
15 |
30 |
Weight Maintenance |
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and Nutrition follows the government |
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recommendations |
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Ornish |
High fiber, low fat, vegetarian diet |
1580 |
55 |
15 |
30 |
Weight Maintenance |
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The Sonoma Diet Connie Guttersen RD, PhD
|
Influenced by a Mediterranean plant-based diet. This three phase diet places emphasis on a variety of flavorful, nutrient dense "power foods" like almonds, bell peppers, blueberries, broccoli, grapes, olive oil, spinach, strawberries, tomatoes, and whole grains. |
1500 for men |
50-55 |
15-20 |
30 |
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Low Calorie |
||||||
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1200 for women |
50-55 |
15-20 |
30 |
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||
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Low Calorie |
||||||
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The Cheaters Diet Paul Rivas MD
|
Based on the plate method: 1/2 plate vegetables, 1/4 whole grains, 1/4 lean protein. Dr. Rivas reports that you must cheat on the weekends to stroke your Metabolism and boost fat loss. He suggests eating whatever you want from 9am on Saturday to 9pm on Sunday. |
1200-excissive calories
|
50
|
20
|
30
|
Weight Maintenance
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The Supermarket Diet Janis Jibrin MS, RD
|
Provides shopping lists, meal plans, recipes and snacks. The book begins with at two week boot camp phase. The author helps readers select which calorie level is the best fit for them, and how to troubleshoot problems if the calorie level does not seem to be yielding results. |
1200-1500
|
50
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20
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30
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Low Calorie Weight Maintenance
|
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The internet provides some excellent resources for those who want and need more information.
Two
types of programs are available; those that primarily provide
information and others that actually counsel the individual and
provide low calorie diets and other advice. Sound internet resources
that can help those who are trying to control their weights are
listed in Table 14. The internet surfer needs to beware that not all
sites providing advice and information are sound. It is best to
trust the sites sponsored by government, professional, and voluntary
associations with some standing and expertise in the weight control
field. A new entry into the weight loss arena in recent years is the
web-based weight control program [110].
These
resources include chat rooms, diet and exercise information, and
often products that are for sale. For example, Nutrisystem.com
requires the purchase of prepackaged foods as well as providing a web
site. The e-diet.com website charges for a visit to its site. It
provides shopping lists from which consumers self select foods, and
also it provides general advice.
These web-based commercial offerings vary in their quality, some are very good and others are poor [31].
|
Table 14. Internet Resources for Weight Control 110, 111, 112, 113 |
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Type of Site and Name |
Internet address and Comments |
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Advice and Information on nutrition and weight control |
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American Dietetic Association |
This is the website for nutrition professionals. Membership allows entrance to the Journal of the American Dietetic Association and the Evidenced Based Library. |
|
Shape Up! America |
Founded in 1994, Shape Up America! is a 501(c)3 not-for-profit organization committed to raising awareness of obesity as a health issue and to providing responsible information on healthy weight management. |
|
American Obesity Association |
Comprehensive website dedicated to obesity. This website offers information on treatment, prevention, education and various aspects of public policy. |
|
National Institutes of Health |
The website is home to the Dietary Guidelines, Mypyramid which is an interactive diet and physical activity planner, and an abundance of information regarding health nutrition. |
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Web-Based Aids for Dieters |
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www.cyberdiet.com |
|
WebMD Nutrition Resources |
www.mywebmd.nutrition.com |
|
Ediets.com |
www.ediets.com |
|
Weight Watchers Online |
www.weightwatchers.com |
|
Nutricise.com |
Nutricise.com One-on-one private e-mail counseling with a registered dietitian is the focus of this program. Members receive individually tailored and informative e-mails from their assigned coach. The focus is to gradually break the unhealthy patterns that lead to extra pounds and trade them for a new healthy lifestyle. Membership is $174.95, which covers the first six months of counseling. After the initial six months, the rate is $9.95 per month to continue. Breaking the Pattern (Red Mill Press, 2001), a book by Charles Stuart Platkin, is included. |
|
Lifepractice.com |
Lifepractice.com The LifePractice program deals with exercise, nutrition, sleep habits and stress management. A personal coach is assigned to each member. Frequent e-mails and daily tracking of the member's progress is standard. The cost is $3.50 per week. |
|
Changeone.com |
Changeone.com This is a 12-week program with the focus on making small changes each week. Each week a small change is tackled with the goal of leading to a healthier lifestyle and weight loss. The current price is $9.95 a month. |
|
Fitday.com |
Fitday.com This website is a free online journal that tracks and analyzes food intake, exercise, and weight loss goals. |
|
Caloriescount.com |
Caloriescount.com This site boasts several online calculators that help the participant keep track of their weight loss. Tools, such as The Enhanced Calorie Calculator, let the participant chose from thousands of foods with the option to download to their home computer and track the progress. The cost is $25 for six months, and the first month is free. |
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Those who are moderately obese with few risk factors and who need additional support and information after they have been screened by a physician on weight reduction may find these resources useful. They are not freestanding and need to be administered in conjunction with some additional health and dietary counseling about a hypocaloric diet from a physician or registered dietitian.
The internet is widely available at all times of the day or night, at low cost. For example, the US Army has developed a web-based dietary advice program that can be used at Army bases around the world.
High risk patients, especially those who lack economic resources, may attempt to use these internet sites for the primary treatment of their condition. Also some sites provide inappropriate or wrong advice. There is little personal supervision or support of the dieter.
The safety and effectiveness of internet sites for weight reduction has not been established [49]. Only recommended sites should be trusted.
Self-help programs led by laypersons are voluntary programs that charge very low or no fees. National organizations include TOPS (Take Off Pounds Sensibly), OA (Overeaters Anonymous), and others. These programs are designed primarily to provide group support to those who have weight problems, rather than to provide and supervise weight reduction diets.
Current guidelines for the composition of weight reducing diets, as discussed above, are outlined in the 2005 Dietary Guidelines for Americans (Table 1).
Once the obese individual has lost body fat, his or her healthier weight and fatness studies must be maintained. Thus the energy deficit phase of weight control is followed by the weight maintenance phase. It involves alterations in dietary intake and physical activity from levels prior to the onset of the dietary treatment. Paradoxically, the slimmer individual’s energy needs are lower to stay in energy balance than they were prior to weight reduction. The primary reason for this is that some loss of lean as well as fat tissue inevitably occurs on reducing diets. Metabolically active tissue is reduced and resting metabolism is decreased after weight loss. Also, it takes less effort to move the lighter body, so the energy cost of physical activity is thus reduced. The implications are that a slight decrease in energy intake from prior levels and an increase in energy output will be necessary during weight maintenance. There is a need for continued attention to these factors on the part of the physician and patient. Behavior modification necessary to sustain these lifestyle changes is best practiced during the weight loss phase, and maintained thereafter. All too often the weight maintenance phase is neglected or ignored, and weight is regained over the long term [31]. The best way to maintain energy balance in the face of lower energy needs over the long term is an important question that still has not been answered satisfactorily [114]. Some factors that seem to be associated with long-term successful weight maintenance include continued regular exercise and to a lesser extent, use of low calorie, low fat diets relatively high in fruits and vegetables. Also, continued self-monitoring of the amount and type of food consumed and of physical activity levels may help [31].
Although energy needs are less during weight maintenance, the requirements for protein, essential fatty acids, carbohydrate, dietary fiber, vitamins and minerals are similar to those of any normal adult, and should be provided. The Food Pyramid’s macronutrient composition provides approximately 24% fat, 18% protein, 59% carbohydrate, and 22 gm of dietary fiber; with advice that added sugars and fats are to be used sparingly [36]. The 2005 Dietary Guidelines for Americans recommend that all Americans, including those who are watching their weight, to adopt the following habits (see Table 1).
There is currently much dispute about the ideal macronutrient distribution in diets for weight maintenance, but at present very few long-term studies are available. Little is known about the effects of the diet’s macronutrient content on weight maintenance. However, recent data suggest that a combination of a physically activity, moderation in dietary intake, and appropriate behavior modification are key.
A recent study of the self-selected diets of free-living American adults found that diets high in carbohydrate (above 55% of calories) were lower in energy and in the calories per gram of food they supplied and were associated with the lower BMI’s than those consuming less carbohydrate. The nutrient density (amount of the nutrient per calorie consumed) was also higher for vitamins A, Vitamin C, carotene, folate, calcium, magnesium, and iron, but lower in vitamin B-12 and zinc than those with lower intakes of carbohydrates. Also, the high carbohydrate group ate more low fat foods, grain products and fruits and had the lowest sodium intakes of the groups studied [115].
Other studies suggest that energy density of the diet rather that the macronutrient composition of the diet affects energy intake the most markedly [116, 117]. One review found that low fat, high fiber diets were the most effective in promising weight loss, and that their effects appeared to be associated with their energy density [118], whether this is true in weight maintenance remains to be determined. There may be macronutrient effects on hunger and satiety that operate through endocrine and metabolic mechanisms such as leptin, insulin, grhelin, adiponectin and other hormones only now being discovered that regulate food intake and that differ depending on these dietary characteristics. Additionally the macronutrient composition of habitual diets also affects health risks, and these must also be considered. Other effects of usual diets on weight maintenance may be genetic. Finally psychological and behavioral factors may vary on different macronutrient combinations. Currently these topics are the subject of much debate, but research is needed to clarify what and which nutrient composition is optimal and how best to help people modulate their energy intakes regardless of dietary composition.
Although much remains to be discovered about the optimal dietary pattern for weight maintenance, a strong case can be made for keeping dietary fat levels below 30% of Calories. In studies in which dietary fat was reduced from 35% to 25% of Calories with no other recommendations, energy intake was reduced and weight was lost [119]. It was estimated that reducing fat by 10% to within the range of 20%-30% of Calories would result in a loss of about 16gm of body fat a day owing to reduction in energy intakes. However, moderation in caloric intake is also in order, since in studies of free-living humans ranging from dietary changes produced only modest body weight losses of about 1-3kg [120, 121, 95]. Low fat diets consumed on an ad-libitum basis tend to be high in carbohydrate, but LDL cholesterol decreases, plasma triglycerides tend to normalize, and so do HDL/total cholesterol ratios [122]. Finally, weight control may be easier [123].
Although the influence of dietary fiber on energy regulation is still not clear, increases of dietary fiber of about 15 grams appear to be associated with decreased energy intakes and body weight losses of about 2 kg over several months, and the effects may be greater in overweight persons [94]. However, these effects are not yet confirmed. Since dietary fiber intakes are currently low, only about 15 grams per day in most Americans, and recommendations are for nearly twice that much, increased fiber levels seem to be appropriate, regardless.
Long term follow-up of health outcomes demonstrates the need for permanent changes in weight toward healthier levels. The relative lack of effects of temporary downward fluctuations underscores the need for long-term weight maintenance. Data collected from individuals successful at weight loss and maintenance have enhanced our understanding of the most effective strategies in the prevention of relapse and long term maintenance of healthier weights. Attention to moderation in dietary intake and the maintenance of high levels of physical activity is vital [124, 125, 126, 127]. Behavioral and attitude adjustments are also important. Encouraging data suggest that behaviors associated with maintenance of weight loss require less effort and become more pleasurable over time [15]. In a recent telephone survey, 48% of individuals who had ever lost more than 10% of their body weight had maintained this loss for at least one year, and 26% had maintained for at least 5 years [128]. Although these data are self reported, they suggest progress in the avoidance of relapse and weight gain.
Most individuals appear to be aware of and use recommended measures, such as increased physical activity, decreased fat intake, decreased food portions, and decreased energy intakes. The problem is that they do so, but not for enough of the time. However, it is also true that dieting efforts often fail, and weight is often rapidly regained, probably negating predicted health benefits. Chronic dieters tend to be food-preoccupied, distractible, emotional, binge-prone, and unhappy, particularly when the diets are very restrictive [129].
About 39% of women and 21% of men in Western countries have ever tried to lose weight, and approximately 24% of women and 8% of men report that they currently are on a "diet". In contrast, about 25% of men and 30% of women report that they are watching what they eat to avoid weight gain or to maintain their weights at current levels [130]. Hypocaloric diets to induce loss of body fat therefore appear to be a common component of the weight control efforts of many people.
These realities and disadvantages have rightly led to questions about whether dieting is "worth it", and whether the treatment is worse than the disease. Certainly they suggest that quality of life measures should be included in studies of reducing diets.
This chapter has stressed the role of the dietary treatment of obesity as a part of a comprehensive program of weight control that includes increased physical activity, lifestyle modification, appropriate intakes of nutrients to minimize chronic disease risk, and eating patterns that maximize quality of life. Such dietary treatment in those with mild to moderate obesity helps to decrease risk factors over the baseline weights after five years. Therefore some health benefit, although it is limited, may be present. However, the health risk/benefit may be negative when dieting entails a cycle of rapid loss followed by equally rapid weight gain. From the standpoint of quality of life and mental health, psychosocial problems do not appear to be inevitable accompaniments of weight loss [130]. Therefore, on balance, dietary approaches to obesity management do appear to be worthwhile, if and only if they are viewed as only one component of a long term weight control program to keep weights and risks at healthier levels. Weight control is "Worth it"!
