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This article combines two articles that originally
appeared in the
July-August 1994 and January-February 1996 issues of FDA Consumer
and contains revisions made in May 1998
by Marilynn Larkin
Americans trying to lose weight have plenty of company. According to a 1995 report from the Institute of Medicine (IOM), tens of millions of Americans are dieting at any given time, spending more than $33 billion yearly on weight-reduction products, such as diet foods and drinks.
Yet, studies over the last two decades by the National Center for Health Statistics show that obesity in the United States is actually on the rise. Today, approximately 35 percent of women and 31 percent of men age 20 and older are considered obese, up from approximately 30 percent and 25 percent, respectively, in 1980.
The words obesity and overweight are generally used interchangeably. However, according to the IOM report, their technical meanings are not identical. Overweight refers to an excess of body weight that includes all tissues, such as fat, bone and muscle. Obesity refers specifically to an excess of body fat. It is possible to be overweight without being obese, as in the case of a body builder who has a substantial amount of muscle mass. It is possible to be obese without being overweight, as in the case of a very sedentary person who is within the desirable weight range but who nevertheless has an excess of body fat. However, most overweight people are also obese and vice versa. Men with more than 25 percent and women with more than 30 percent body fat are considered obese.
Many people who diet fail to lose weight--or, if they do lose, fail to maintain the lower weight over the long term. As the IOM report, "Weighing The Options: Criteria for Evaluating Weight-Management Programs," points out, obesity is "a complex, multifactorial disease of appetite regulation and energy metabolism."
Because many factors affect how much or how little food a person eats and how that food is metabolized, or processed, by the body, losing weight is not simple. For example, recent studies suggest a role for genetic makeup in obesity. This area is still controversial, and more studies will be needed before scientists can say with certainty that a person's genes may set limits on how much weight can be lost and maintained.
Yet many people persist in seeking simple cures to this complex health problem. Lured by fad diets or pills that promise a quick and easy path to thinness, they end up disappointed when they regain lost weight.
"There are no shortcuts--no magic pills," says Lori Love, M.D., Ph.D., of the Food and Drug Administration's Center for Food Safety and Applied Nutrition. Losing weight sensibly and safely requires a multifaceted approach that includes setting reasonable weight-loss goals, changing eating habits, and getting adequate exercise. Appetite suppressants (diet pills) or other products may help some people over the short term, but they are not a substitute for adopting healthful eating habits over the long term.
The first step in losing weight safely is to determine a realistic weight goal. The table, at right, developed by the U.S. Department of Agriculture and the Department of Health and Human Services, offers a range of suggested weights for adults based on their height.
A physician, dietitian or nutritionist also can help you set a reasonable goal. To reach the goal safely, plan to lose 1 to 2 pounds weekly by consuming approximately 300 to 500 fewer calories daily than usual (women and inactive men generally need to consume approximately 2,000 calories to maintain weight; men and very active women may consume up to 2,500 calories daily).
Moderation, Variety and Balance
After determining a reasonable goal weight, devise an eating plan based on the cornerstones of healthful eating--moderation, variety and balance, suggests Victor Herbert, M.D., J.D., professor of medicine and director of the Nutrition Center at the Mount Sinai School of Medicine and Bronx VA Medical Centers in New York City, and member of the board of directors of the National Council Against Health Fraud.
"Moderation means not eating too much or too little of any particular food or nutrient; variety means eating as wide a variety as possible from each, and within each, of the five basic food groups; and balance refers to the balance achieved by following moderation and variety, as well as the balance of calories consumed versus calories expended," he explains. To lose weight, fewer calories should be consumed than expended; to maintain weight loss, the number of calories consumed and expended should be about the same.
Because fat is the most concentrated source of calories (9 calories per gram compared to 4 calories per gram for carbohydrate and protein), it is usually the focus of weight-maintenance and weight-loss diets. Limiting fat intake alone will likely limit calories, as well. Just as for the general population, weight-conscious consumers should limit fat intake to no more than 30 percent of total calories, according to the Dietary Guidelines for Americans.
Alcoholic beverages also are a source of calories (7 per gram of alcohol). Twelve ounces of regular beer, for example, provides 150 calories; the same amount of "light" beer, 105 calories. Five ounces of wine or 1.5 ounces of 80-proof distilled spirits provide 100 calories. But alcohol provides few, if any, nutrients, so if you drink alcoholic beverages and want to reduce your weight, consider reducing or eliminating your alcohol intake.
In selecting your diet, follow the five basic food groups and the recommended number of servings from each as incorporated into the Food Guide Pyramid developed by USDA and HHS. These groups are (1) bread, cereal, pasta, and rice; (2) vegetables; (3) fruits; (4) milk, yogurt and cheese; and (5) meat, poultry, fish, dry beans, eggs, and nuts. A sixth group (fats, oils and sweets) consists mainly of items that are pleasing to the palate but high in fat and/or calories; these should be eaten in moderation.
Avoid low-calorie fad diets that exclude whole categories of food such as carbohydrates (bread and pasta) or proteins (meat and poultry). These diets may be harmful because they generally do not include all nutrients necessary for good health. "Every fad diet that demands an unusual eating pattern, such as emphasizing only a few types of foods, deviates from one or more of the guidelines of moderation, variety and balance," says Herbert. "The greater the deviation, the more harmful the diet is likely to be."
Using the Food Label
To help consumers plan a healthful diet, FDA and USDA have revamped food labels. By law, most food labels now must display a Nutrition Facts panel containing information about how the food can fit into an overall daily diet. Nutrition Facts state how much saturated fat, cholesterol, fiber, and certain nutrients are contained in each serving.
On the food label, %Daily Value shows what percentage of a given nutrient is provided in one portion for daily diets of 2,000 calories.
Whether or not a given food fits into a weight-loss diet depends on what other foods you eat that day. For most people, the goal is to select a variety of foods that together add up to approximately 100 percent of the Daily Value for total carbohydrate, dietary fiber, vitamins, and minerals; total fat, cholesterol and sodium each may add up to less than 100 percent.
Foods that claim to contain fewer calories or less fat than similar servings of similar products must show the difference on the label. For example, on a container of low-fat cottage cheese, the label would show that a serving of the low-fat product contains 80 calories and 1.5 grams of fat while regular cottage cheese contains 120 calories and 5 grams of fat per serving.
Camille Brewer, a registered dietitian and nutritionist in FDA's Office of Food Labeling, advises caution, however, when choosing foods that are labeled "fat-free" and "low-fat." Some of these foods, like "low-fat" cakes and cookies, still may be high in calories because of added sugars. So dieters should always check the Nutrition Facts panel to get complete information, she says.
Look for foods high in fiber, such as fruits, vegetables, legumes and whole grains. Fiber can be an important aid in weight maintenance because eating enough of it can help make a person feel full and thus not eat as much.
To see how the new label can help you stick to your diet, see Dieters' Label Checklist (a 119K PDF file)
Regular exercise is important for overall health, as well as for losing and maintaining weight. There is evidence to suggest that body fat distribution affects health risks. For example, excess fat in the abdominal area (as opposed to hips and thighs) is associated with greater risk for high blood pressure, diabetes, early heart disease, and certain types of cancer. Vigorous exercise can reduce abdominal fat and thus lower the risk of these diseases.
The Dietary Guidelines for Americans recommends a half hour or more of moderate physical activity on most days, preferably every day. The activity can include brisk walking, calisthenics, home care, gardening, moderate sports exercise, and dancing. Regular exercise can help the body use up calories consumed daily, as well as excess calories stored as fat. Weight-bearing exercises also help tone muscles and may reduce the risk of osteoporosis.
OTC Diet Pills
The 1991/1992 Weight Loss Practices Survey, sponsored by FDA and the National Heart, Lung, and Blood Institute, found that 5 percent of women and 2 percent of men trying to lose weight use diet pills. Products considered by FDA to be over-the-counter weight control drugs are primarily those containing the active ingredient phenylpropanolamine (PPA), such as Dexatrim and Acutrim. PPA is available OTC for weight control in a 75-mg controlled-release dosage form, when combined with a restricted diet and exercise.
Using diet pills containing PPA will not make a big difference in the rate of weight loss, says Robert Sherman of FDA's Office of OTC Drug Evaluation. "Even the best studies show only about a half pound greater weight loss per week using PPA combined with diet and exercise," he adds. Sherman cautions that the recommended dosage of these pills should not be exceeded because of the risk of possible adverse effects, such as elevated blood pressure and heart palpitations.
Since PPA is also used as a nasal decongestant in over-the-counter cough and cold products, consumers should read the labels of OTC decongestants to see if they contain PPA. They should not take PPA in two products labeled for different uses.
Sherman notes that FDA has received a small number of reports indicating that PPA use might be associated with an increased risk of stroke. A large-scale safety study was begun in September 1994 to explore the possibility. Based on available data, the agency does not believe that an increased risk of stroke is a concern when PPA is used at recommended dosages.
FDA has approved several prescription drugs for obesity. Those available on the market include:
In mostly short-term studies of obese adults following a calorie-restricted diet, those who took the appetite suppressants lost more weight on average than those who took a placebo. The amount of weight lost varied from study to study.
FDA approved the drugs only for use with calorie-restricted diets. The drugs are "not magic pills," warns Leo Lutwak, M.D., Ph.D., of FDA's division of metabolism and endocrine drug products. "They don't work unless you make dietary and exercise changes."
Also, they should be used only for a few weeks because the drugs are addictive and have the potential for abuse. They shouldn't be used in combination with each other or with other drugs for appetite control because such combinations have not been evaluated for safety. And the drugs should be used only in people who are obese--not people looking to lose a few pounds, Lutwak says.
"Weight-loss drugs are serious medicine for a serious disease," he says.
Also, he points out that while obesity may be associated with other serious diseases, studies have never shown that weight loss produced with the use of prescription weight-loss drugs benefits obesity-associated conditions. However, changes in diet and activity may improve associated diseases, such as diabetes and high blood pressure, even with only modest changes in weight, Lutwak says.
Until September 1997, two other drugs, fenfluramine (Pondimin and others) and dexfenfluramine (Redux), were available for treating obesity. But, at FDA's request, the manufacturers of these drugs voluntarily withdrew them from the market after newer findings suggested that they were the likely cause of heart valve problems in a large proportion of people using them. FDA recommended that anyone taking the drugs stop and that they contact their doctor to discuss their treatment. (For the latest information on this topic, visit www.fda.gov/cder/news/feninfo.htm on FDA's Website.)
Many people turn to weight-loss programs for help in planning a daily diet and changing lifestyle habits. The IOM report provides guidelines for evaluating the potential effectiveness of such programs.
"To improve their chances for success, consumers should choose programs that focus on long-term weight management; provide instruction in healthful eating, increasing activity, and improving self-esteem; and explain thoroughly the potential health risks from weight loss," according to the report. Consumers should also demand evidence of success. If it is absent or consists primarily of testimonials or other anecdotal evidence, "the program should be viewed with suspicion."
IOM recommends that potential clients be given a truthful, unambiguous, non-misleading statement about the program's approaches and goals, and a full disclosure of costs. The cost breakdown should include initial and ongoing costs, as well as the cost of extra products.
The basic tenet of weight loss--to eat fewer calories than you burn and to stay active--is easy to say but, like most lifestyle changes, not so easy to do. With realistic goals, and a commitment to losing weight slowly, safely and sensibly, the chances of long-term success improve dramatically. n
Marilynn Larkin is a writer in New York City. Paula Kurtzweil, a member of FDA's public affairs staff, also contributed to this article.
Obesity is now considered a disease--not a moral failing. According to a 1995 report from the Institute of Medicine, "obesity is a heterogeneous disease in which genetic, environmental, psychological, and other factors are involved. It occurs when energy intake exceeds the amount of energy expended over time. Only in a small minority of cases is obesity caused by such illnesses as hypothyroidism or the result of taking medications, such as steroids, that can cause weight gain."
Public health concerns about this disease relate to its link to numerous other diseases that can lead to premature illness or death. The report notes that overweight individuals who lose even relatively small amounts of weight are likely to:
Of course, losing excess weight is also likely to improve appearance, which is a strong motivation for many people.
Publication No. (FDA) 98-1287
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