Diet and Weight–Loss Lore, Myths, and Controversies

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Diet and Weight–Loss Lore, Myths, and Controversies

One of the challenges facing public-health professionals as they seek to combat obesity among Americans is helping consumers to distinguish myths, lore, legends, and outright fraud from accurate, usable information about nutrition, diet, exercise, and weight loss. Some of these inaccuracies are so long-standing and deeply rooted in American culture that even the most educated consumers unquestioningly accept them as facts. Others began with a kernel of truth but have been so wildly distorted or misinterpreted that they are confusing, misleading, or entirely erroneous. The rapid influx and dissemination of information about the origins of overweight and obesity and conflicting accounts of how best to treat these problems compound the challenge. With media reports and advertisements trumpeting different diets nearly every week, it is no wonder that Americans are confused about diet and weight loss.

The fiction that people who are overweight or obese are lazy and weak-willed is among the most harmful myths because it serves to promote stigma, bias, and discrimination. Another common misconception is that it is equally easy or difficult for all people to lose weight. There are biological and behavioral factors that affect an individual's body weight, and people vary in terms of genetic propensity to become overweight, basal metabolic rate (BMR), and the number of fat cells. BMR, often referred to simply as the metabolic rate, is the number of calories an individual expends at rest to maintain normal body functions. BMR changes with age, weight, height, gender, diet, and exercise habits and has been found to vary by as much as one thousand calories per day. Differences in metabolic rate explain, in part, why not all people who adhere to the same diet achieve the same results in terms of pounds lost or rate of weight loss. Another factor that produces variation in weight loss is the number of fat cells in the dieter's body. Even though fat cells do not determine body weight, they are affected by weight gain and act to limit weight loss because their number cannot be decreased. For example, a normal-weight person has about 40 billion fat cells, whereas an individual who weighs 250 pounds with a body mass index (BMI) of 40 may have as many as 100 billion fat cells. Weight loss causes fat cells to shrink in size but does not decrease their number. As a result, individuals with twice as many fat cells as normal-weight people may be able to shrink their fat cells to a normal size but even when they have attained a healthy weight they will still have twice as many fat cells.


It is impossible to recount all the fantastic and improbable claims that have been made in recent years. This section considers some of the most persistent myths about diet, exercise, and weight loss.

Low-Carbohydrate Diets

MYTH. A low-carbohydrate diet is the fastest, healthiest, and best way to lose weight.

FACT. Low-carbohydrate diets may initially produce more rapid weight loss than other diets; however, most of the loss is water weight rather than fat. The water lossoccurs as the kidneys flush out the excess waste products resulting from the digestion of protein and fat. Many low-carbohydrate diets encourage the consumption of high-fat foods, such as butter, heavy cream, bacon, and cheese. Long-term, high-fat diets may raise blood cholesterol levels, and low-carbohydrate, high-protein diets produce a state of ketosis (the accumulation of ketones from partly digested fats as a result of inadequate carbohydrate intake), which may increase the risk of gout (a severe arthritis attack that occurs in one joint—typically the big toe, ankle, or knee—caused by defects in uric acid metabolism) and kidney stones. Furthermore, most nutritionists and researchers concur that even though some weight-loss diets are nutritionally inadequate and others are even dangerously insufficient, nearly all diets can affect weight loss, and currently no compelling evidence exists to proclaim that one diet is vastly superior to another. A key factor in the success of any weight-loss diet is adherence— whether dieters can remain faithful to the regimen they have chosen, and to date low-carbohydrate diets have not demonstrated superiority in terms of adherence. Boredom and frustration with a low-carbohydrate regimen may occur when dieters crave the carbohydrates that they are forbidden or can eat only in small amounts.

Still, there is one unanswered question about diet and weigh loss: Why do some dieters successfully lose weight using low-carbohydrate or low-fat diets, whereas others on thesame diets areunsuccessful?CaraB.Ebbelingetal. assert in ''Effects of a Low-Glycemic Load vs Low-Fat Diet in Obese Young Adults'' (Journal of the American Medical Association, vol. 297, no. 19, May 16, 2007) that which diet will be the most effective for each individual depends in part on the dieter's hormonal profile-specifically on differences in insulin secretion as measured by serum insulin concentration. The researchers compared seventy-three subjects following a low-glycemic load diet or low-fat diet and measured their body weight, body fat, and insulin concentration before and after six months of dieting and during a twelve-month follow-up period. During the six months of dieting, high insulin secretors lost more weight (2.2 pounds per month) on the low-glycemic-load diet, than on the low-fat diet (0.9 pounds per month). After eighteen months, the high insulin secretors had lost a total of 12.8 pounds on the low-glycemic-load diet, compared to just 2.6 pounds on the low-fat diet. The low-glycemic-load dieters also lost more body fat than the low-fat dieters and were more successful at maintaining their weight losses. In contrast, dieters who were considered low insulin secretors fared equally well on both diets. Ebbeling et al. also observed that independent of insulin secretion status, the low-glycemic-load diet had beneficial effects—high-density lipoprotein increased and triglycerides decreased. Subjects on the low-fat diet did not realize these benefits, but did experience reductions in low-density lipoprotein.

Calorie Reduction

MYTH. The dieter needs to cut calories drastically to lose weight.

FACT. Weight loss may be accomplished with modest reductions in calorie consumption. Low-calorie diets often result in metabolic adaptations, such as a significant reduction in resting metabolic rate, which may produce weight maintenance or even weight gain rather than the desired weight loss. Many nutritionists and diet plans advise simultaneously reducing total caloric-intake and modifying the balance of macronutrients (nutrients that the body uses in relatively large amounts: carbohydrates, fats, and proteins)—some weight-loss diets reduce fat intake, others reduce carbohydrates.

Negative-Calorie Foods

MYTH. It takes more calories to eat and digest some foods such as celery or cabbage than these foods contain, so eating them causes or speeds weight loss.

FACT. There are no foods that when eaten cause weight loss. Foods containing caffeine may temporarily boost metabolism but they do not cause weight loss. However, some recent evidence suggests that eating grapefruit or drinking grapefruit juice may help people who are obese to lose weight. Ken Fujioka et al. at the Scripps Clinic in San Diego, California, compared weight loss over a twelve-week period among one hundred obese individuals. One-third of the subjects ate half a grapefruit before each meal three times per day, whereas another drank a glass of grapefruit juice before every meal. The third group did not include grapefruit in their meals. According to Marina Murphy, in ''Grapefruit Diet Works and May Prevent Diabetes'' (Chemistry and Industry, no. 3, February 2, 2004), Fujioka et al. reported that after twelve weeks subjects who ate grapefruit lost an average of 3.6 pounds, and those who drank grapefruit juice lost an average of 3.3 pounds, whereas those in the control group who consumed no grapefruit lost an average of 0.5 pounds. Fujioka et al. attributed the weight loss to lowered levels of insulin, which were confirmed by measurements of blood glucose and insulin levels. They posited that the more efficiently sugar is metabolized, the less likely it is to be stored as fat. Furthermore, lowering insulin levels reduces feelings of hunger—elevated insulin levels stimulate the brain's hypothalamus, producing feelings of hunger.

Eating at Night

MYTH. Eating after 8:00 PM causes weight gain.

FACT. Weight gain or loss does not depend on the time of day food is consumed—excess calories will be stored as fat whether they are consumed midmorning or just before bedtime. In general, weight is governed by the amount of food consumed measured in total calorie count, and the amount of physical activity expended during the day.

There is, however, evidence that eating early in the day and eating breakfast are habits associated with maintaining a healthy weight. In ''Make It an Early Bird'' (New York Times, November 21, 2007), Jennifer Ackerman indicates that research reveals that people who eat breakfast tend to consume fewer calories throughout the day, compared to those who make dinner their biggest meal. This may be because the system in the brain that signals satiety (the feeling of fullness or satisfaction after eating) is more effective early in the day—at night an individual may be more prone to succumb to overeating.

Natural Weight-Loss Products

MYTH. Organic, natural, or herbal weight-loss products are safer than synthetic (produced in the laboratory) over-the-counter (nonprescription) or prescription drugs.

FACT. Simply because products are organic or naturally occurring does not necessarily mean that they are risk-free or safe. For example, according to the press release ''FTC Charges Direct Marketers of Ephedra Weight Loss Products with Making Deceptive Efficacy and Safety Claims'' (July 1, 2003,, in July 2003 the Federal Trade Commission (FTC) took action against the marketers of weight-loss products containing ephedra, which is derived from a leafless desert shrub, and hydroxycitric acid, which is an extract from brindall berries. The actions targeted deceptive effectiveness, safety, and side-effect claims for weight-loss supplements containing these dietary supplements. The FTC challenged advertising claims that ephedra and other natural supplements caused rapid, substantial, and permanent weight loss without diet or exercise, as well as the claims that these weight-loss products are ''100% safe,'' ''perfectly safe,'' or have ''no side effects.''

Low-Fat and Low-Carbohydrate Foods

MYTH. Low fat or nonfat means few or no calories.

FACT. A low-fat or nonfat food is usually lower in calories than the same size—as measured by weight— portion of the full-fat food; however, a food product can contain zero grams of fat and still have a high calorie content. Many fat-free foods replace the fat with sugar and contain just as many or more calories as full-fat versions. Even though most fruits and vegetables are naturally low in fat and calories, processed low-fat or nonfat foods may be high in calories because extra sugar, flour, or starch thickeners have been added to enhance the low-fat foods' taste or texture.

Similarly, low-carbohydrate foods are often higher in calories than their ''regular'' counterparts because their fat content is higher. Many foods that are naturally low in carbohydrates such as meat, butter, and cheese are also calorie-dense. Many nutritionists suggest limiting the consumption of low-carbohydrate versions of foods, such as low-carbohydrate frozen desserts, because they not only contain as many or more calories per serving than ice cream but also are often sweetened with artificial sweeteners that lack any nutrients.

Eliminating Starchy Foods

MYTH. Pasta, potatoes, and bread are fattening foods and should be eliminated or sharply limited when trying to lose weight.

FACT. Potatoes, rice, pasta, bread, beans, and some starchy vegetables such as squash, yams, sweet potatoes, turnips, beets, and carrots are not innately fattening. They are rich in complex carbohydrates, which are important sources of energy. Furthermore, foods that are high in complex carbohydrates are often low in fat and calories because carbohydrates contain only four calories per gram, compared to the nine calories per gram contained by fats. In ''Effects of an Ad Libitum Low-Fat, High-Carbohydrate Diet on Body Weight, Body Composition, and Fat Distribution in Older Men and Women'' (Archives of Internal Medicine, vol. 164, no. 2, January 26, 2004), Nicholas P. Hays et al. report the results of a small study in which dieters lost substantial amounts of weight on a high-carbohydrate, low-fat regimen. Meals were prepared for the subjects, who were told to eat as much as they wanted and to return any uneaten food, which enabled the researchers to calculate the subjects' caloric intake. Surprisingly, subjects who consumed a high-carbohydrate, low-fat diet with no quantity or caloric restrictions lost significant amounts of weight. The researchers speculate that low-fat, high-carbohydrate diets may reduce body weight via reduced food intake, because complex carbohydrate-rich foods are more satiating and less energy-dense than higher-fat foods and conclude that their ''data support the alteration of dietary macronutrient composition without emphasis on caloric restriction as an effective means of promoting weight loss.''

Genetic Destiny

MYTH. People from families where many members are overweight or obese are destined to become over-weight.

FACT. It is true that studies of families find similarities in body weight and that immediate relatives of obese people are at an increased risk for overweight and obesity, compared to people with normal-weight family members. Even though it is generally accepted that genetic susceptibility or predisposition to overweight or obesity is a factor, researchers believe that environmental and behavioral factors make equally strong, if not stronger, contributions to the development of obesity. As a result, people from overweight or obese families may have to make concerted efforts to maintain healthy body weight and prevent weight gain, but they are not destined to become obese simply by virtue of the genes they inherited.

Exercise Alone

MYTH. Exercise is a better way to lose weight than dieting.

FACT. Even though there are many health benefits from exercise, weight loss is not generally considered a direct benefit. Research has consistently demonstrated that for weight loss, diet trumps exercise because it is simpler to reduce caloric intake significantly through diet than to increase caloric expenditure significantly through exercise. For example, if a 155-pound person wished to reduce his or her consumption by 400 calories per day, it might be achieved by simply eliminating dessert and reducing portion sizes. In contrast, expending four hundred calories requires considerable effort. To burn 400 calories, a 155-pound person would have to spend an hour bicycling at about ten miles an hour; hiking cross country, mowing the lawn, or ice skating at nine miles per hour; or water skiing or walking uphill at about 3.5 miles per hour. However, many studies demonstrate that exercise is an important way to prevent overweight and maintain weight loss.

Cris A. Slentz et al. find in ''Effects of the Amount of Exercise on Body Weight, Body Composition, and Measures of Central Obesity: STRRIDE—A Randomized Controlled Study'' (Archives of Internal Medicine, vol. 164, no. 1, January 12, 2004) that as little as thirty minutes of walking daily is enough exercise to prevent weight gain for most sedentary people, and that exertion above that may even cause weight and fat loss. The investigators randomly assigned 182 overweight, inactive adults aged forty to sixty-five to one of three programs of escalating exercise or to a control group that did not exercise for eight months. One group did the equivalent of twelve miles of walking per week, another completed the equivalent of twelve miles of jogging per week, and the most intense exercise group performed exercise comparable to jogging twenty miles per week. All the exercise was performed on treadmills, elliptical trainers, or stationary bicycles in supervised settings. The subjects were encouraged not to change their diets during the study.

Subjects in the two low-level exercise groups lost weight and fat, and those in the most intense exercise program lost more weight and fat than the others. The vigorous exercise group had a 3.5% weight loss and the two low-dose groups had slightly more than a 1% weight loss, whereas the control group had a 1.1% weight gain. Exercise dose and intensity also determined changes in waist circumference—subjects who did not exercise had a 0.8% increase in waist circumference. The two groups doing the lower amounts of exercise had decreases of about 1.5%, and the most intensely exercising group reported a waist decline of 3.4%. Slentz et al. determine that a modest amount of exercise-thirty minutes per day—can prevent weight gain without changes in diet.

Eating Disorders

MYTH. Eating disorders occur exclusively among middle- and upper-class white females.

FACT. Like many myths about diet, weight, and nutrition, this one is based on fact: an estimated 90% of people with anorexia nervosa or bulimia nervosa are female; however, according to Susan Z. Yanovski of the National Institutes of Health in ''Eating Disorders, Race, and Mythology'' (Archives of Family Medicine, vol. 9, no. 1, January 2000), binge-eating disorder occurs in both genders and across all socioeconomic classes. Yanovski attributes the myth that eating disorders are limited to middle- and upper-class white women to the fact that many studies were conducted on college campuses where few minority students were enrolled, and other research looked at people seeking treatment, often at referral centers. Yanovski observes that ''studies done on such populations, which may be more likely to be white and of higher socioeconomic status, have limited generalizability.'' She also cites research that finds that minorities are substantially affected by eating disorders—one study found that African-American women were as likely as white women to report binge eating. Another revealed that the prevalence of binge eating was comparable among Hispanic, non-Hispanic white, and African-American women, but that binge-eating symptoms were more severe among the Hispanic group. Yanovski concludes that the ''recognition that eating disorders are color-blind can ensure that appropriate recognition and treatment are available to all patients at risk.''

Anna Keski-Rahkonen et al. indicate in ''Epidemiology and Course of Anorexia Nervosa in the Community'' (American Journal of Psychiatry, vol.164,no.8, August 2007) that there is a substantially higher lifetime prevalence of anorexia nervosa than reported in previous studies—as high as 270 cases per 100,000 among women between the ages of fifteen to nineteen. Keski-Rahkonen et al. also offer a hopeful finding: most young women recovered within five years and usually progressed to full recovery.


Historically, diets have been considered to have ''failed'' when lost weight is regained. Many nutritionists and obesity researchers believe that diets fail because most are not sustainable. The more restrictive the diet, the less likely an individual will be to remain faithful to it because, in general, people cannot endure extended periods of hunger and deprivation. Another reason diets may fail is that they neglect to teach dieters new eating habits to assist them to maintain their weight loss. Most over-weight people gained their excess weight by consuming more calories per day than they needed. Dieting creates a temporary deficit of calories or specific macronutrients such as carbohydrates or fat. Because the weight-loss diet is viewed as a temporary measure with a beginning and an end, at its conclusion most dieters return to their previous eating habits and often regain the lost weight or even more weight. Many nutritionists and dieticians who work with people who are overweight or obese assert that diets do not fail; instead, dieters fail to learn how to eat properly to prevent weight regain.

Consumers are not the only ones who believe that diets are doomed to failure; many health professionals and researchers cite the statistic that 95% of diets fail. This oft-cited statistic has been attributed to Albert Stunkard of the University of Pennsylvania and the director emeritus of the American Obesity Association. Stunkard put forth the 95% failure rate in an account of research he performed in 1959, which involved advising one hundred overweight patients to diet, with no follow-up or support to increase their adherence to the diet. In ''Whether Obesity Should Be Treated?'' (Health Psychology, vol. 12, no.5, September 1993), Kelly D. Brownell observes that this statistic has been widely applied even though it is quite dated, was not confirmed by subsequent studies, and involved only subjects in university-based research programs.

The article ''New Diet Winners: We Rate the Diet Books and Plans'' (Consumer Reports, June 2007) observes that only recently have successful dieters been studied to learn from their successes and incorporate them into more effective, and ideally sustainable, weight-loss plans. It cites as an example the new emphasis on achieving satiety with-out consuming too many calories by consuming low-density foods. This article may help dispel the myth that dieters are doomed to failure.

Improving Long-Term Weight Loss

More recent research demonstrates that dieters find it challenging to maintain weight loss; however, it refutes the 95% failure rate. In ''Successful Weight Loss Maintenance'' (Annual Review of Nutrition, vol. 21, 2001), Rena R. Wing and James O. Hill propose defining ''successful long-term weight loss maintenance as intentionally losing at least 10% of initial body weight and keeping it off for at least one year.'' Using this definition, the investigators offer more favorable outcomes of weight-loss efforts. Wing and Hill report that more than 20% of overweight or obese people can and do lose 10% or more of body weight and maintain the weight loss for more than a year. Analyzing data from the National Weight Control Registry, they also find that people who successfully maintained long-term weight loss—an average weight loss of 66.1 pounds for an average of 5.5 years—shared common behaviors that promoted weight loss and weight maintenance. These behavioral strategies included eating a diet low in fat, frequent self-monitoring of body weight and food intake, and high levels of regular physical activity. Wing and Hill also posit that weight-loss maintenance may become easier over time because they observe that once weight loss had been maintained for two to five years, the chances of longer-term success were greatly increased.

Even though Wing and Hill offer more optimistic estimates of successful weight loss and weight maintenance than what Stunkard reported, there is obviously considerable room for improvement. In ''Long-Term Maintenance of Weight Loss: Current Status'' (Health Psychology, vol.19, no. 1, supplement, January 2000), Robert W. Jeffery et al. identify areas of investigation that might produce strategies to assist more people to control their weight effectively. The researchers assert that despite high rates of dieting and the possibility of long-term success in voluntary weight loss overall, successful weight losses are being offset by failures. Jeffery et al. speculate that the reason for this overall lack of success is that improvements in long-term weight loss have thus far lagged behind improvements in short-term weight loss.

Jeffery et al. describe the typical course of weight loss and regain among people participating in behavioral treatment for obesity as rapid initial weight loss that slows, with maximum weight loss achieved approximately six months after treatment began. Thereafter, weight regain begins and continues until weight stabilizes at or slightly below the starting weight. The investigators speculate that the behavior changes that are prescribed are sufficient for weight loss, and failure to maintain behavior changes may be due to loss of knowledge and skills, loss of motivation, or unpleasant side effects of behavior change such as hunger, psychological stress, or social pressure. Historically, researchers favor either a biological interpretation of the challenge of weight maintenance—the importance of biological determinants of body weight—or a behavioral explanation. Behavioral scientists interpret the weight loss-weight regain pattern as evidence of how difficult it is to achieve lasting change in given the environmental factors that influence behaviors.

Jeffery et al. classify efforts to improve long-term maintenance of weight loss as attempts to increase the intensity of initial treatment, extend the length of treatment, alter dietary and exercise prescriptions, enhance motivation, and teach maintenance-specific behavioral skills. An example of high-intensity obesity treatment is the use of very-low-calorie diets (VLCDs). VLCDs restrict food intake for periods of two to three months to six hundred to eight hundred calories per day, substantially lower than conventional low-calorie diets, which range from one thousand to twelve hundred calories per day. VLCDs consistently produce larger initial weight losses than conventional low-calorie diets. However, they have not proven successful in improving long-term weight loss. The larger, rapid weight losses generated by severe calorie restriction are followed by larger and more rapid regains, which offset the initial losses. Two or more years after treatment, people who were placed on VLCDs fared no better than those who lost weight using less intense regimens.

Treating obesity like chronic diseases such as diabetes and high blood pressure that require ongoing management appears to help; however, attendance at treatment sessions declines over time and is associated with weight regain. Efforts to modify dietary and exercise prescriptions have focused on emphasizing exercise instead of focusing solely on dietary changes. Even though some studies show that the addition of exercise improved shortterm weight loss and weight loss at eighteen-month follow-up visits, exercise was found to slow but not prevent weight regain.

Nutrigenetics (using genetic information to customtailor a weight-loss diet) may help improve the success of weight-loss and weight-maintenance efforts. In ''Improved Weight Management Using Genetic Information to Personalize a Calorie Controlled Diet'' (Nutrition Journal, vol. 6, no.29, October 18, 2007), Ioannis Arkadianos et al. indicate that they offered nutrigenetic testing and developed individual diets to people who historically had failed to lose weight. They compare the results these dieters achieved to a control group that did not receive nutrigenetic screening or a personalized diet and find that subjects in the nutrigenetic group fared better in terms of adherence to their diets, weight loss and maintenance, and improvements in blood glucose levels.

Approaches to enhance motivation focus on two areas: improved social supports and tangible financial incentives. Strategies to improve social supports emphasize including spouses or significant others in the weight-loss process to teach them to provide social support for their partners' weight-loss efforts. Such strategies demonstrate modest success as do contracts in which groups agree to aim for individual or group weight loss.

In ''A Pilot Study Testing the Effect of Different Levels of Financial Incentives on Weight Loss among Overweight Employees'' (Journal of Occupational and Environmental Medicine, vol. 49, no. 9, September 2007), Eric A. Finkelstein et al. find that financial incentives may be effective inducements to lose weight. The researchers followed two hundred overweight workers in North Carolina, who were randomly assigned to one of three groups. One group received no incentives, whereas the other two groups received $7 or $14 for each percentage point of weight lost. For example, a two-hundred-pound subject in the group receiving $7 for each percentage point group who lost ten pounds, or 5% of his or her weight, received $35. Finkelstein et al. find that workers who received the most money and other incentives such as time off lost the most weight. At three months, subjects with no financial incentive lost 2 pounds, those in the $7 group lost approximately 3 pounds, and those in the $14 group lost 4.7 pounds.

Teaching patients skills that are useful for weight maintenance as opposed to weight loss emphasizes that there are two distinctly different sets of strategies: one set focuses on weight loss and the other on maintaining a stable energy balance around a lower weight. The most commonly used model for teaching maintenance-specific skills is relapse prevention, which involves teaching people to identify situations in which lapses in behavioral adherence are likely to occur, to plan strategies in advance to prevent lapses, and to get back on track should they occur. Relapse prevention is based on the idea that breaking the so-called rules in terms of remaining faithful to diet and exercise programs may often lead to negative psychological reactions that in turn prompt reversion to pre-weight-loss behaviors. To date, only one study—Bas Verplanken and Wendy Wood's ''Interventions to Break and Create Consumer Habits'' (Journal of Public Policy and Marketing, vol. 25, no. 1, spring 2006)—has examined the effectiveness of this approach. Verplanken and Wood hypothesize that learning and practicing a well-defined, positive response to relapses might help people sustain weight loss. However, their findings do not support this hypothesis.

Jeffery et al. acknowledge that weight management is a continuing source of fascination and frustration for researchers as well as for dieters. They recommend that research consider additional areas such as:

  • Considering obesity as a chronic disorder requiring continuous care, with the aim of developing cost-effective methods for delivering care indefinitely.
  • Examining psychological, behavioral, biological, and environmental factors that relate to weight loss, maintenance of weight loss, and weight regain to identify the key factors associated with successful long-term weight loss.
  • Improving the assessment of energy intake and expenditure and of behavior patterns associated with change in energy intake and expenditure.
  • Examining the role of behavioral preferences in obesity and its treatment in an effort to answer questions such as: Can behavioral preferences or reinforcement values be changed in ways that would facilitate long-term weight loss? Do they change spontaneously after behavior changes?
  • Researching why long-term outcomes of behavior treatment for obesity in children and adolescents have been more successful than treatment for obesity in adults.
  • Learning more about the role of physical activity and social support in relationship to long-term weight loss.
  • Discovering safer and more effective medications to treat obesity and developing new ways to integrate medications into effective programs of weight control.


There is a long history of marketing so-called miraculous, fat-burning pills, potions, and products to Americans seeking effortless weight loss. Peter N. Stearns, in Fat History: Bodies and Beauty in the Modern West (1997), and Laura Fraser, in Losing It: False Hopes and Fat Profits in the Diet Industry (1998), offer detailed histories of magical cures and weight-loss fads. At the turn of the twentieth century products such as obesity belts and chairs that delivered electrical stimulation, as well as corsets, tonics, and mineral waters, claimed to cause weight loss.

Diet pills arrived on the scene in 1910 with the introduction of weight-loss tablets that contained arsenic (a poisonous metallic element), strychnine (a plant toxin formerly used as a stimulant), caffeine, and pokeberries (formerly used as a laxative). In the 1920s cigarette makers promoted their product as a diet aid, urging Americans to smoke rather than eat. During the 1930s diet pills containing dinitrophenol, a chemical used to manufacture explosives, dyes, and insecticides, enjoyed brief popularity after it was observed that factory workers making munitions lost weight. Their popularity was short-lived, as cases of temporary blindness and death were attributed to their use.

The second half of the twentieth century saw the proliferation of questionable, and often entirely worthless, weight-loss devices and gimmicks, including inflatable suits to ''sweat off pounds,'' diet drinks and cookies, and slimming creams, patches, shoe inserts, and wraps to reduce fat thighs and abdomens. Even though the claims made for many of these products sounded too good to be true, unsuspecting Americans spent billions of dollars in the hope of achieving quick, easy, and permanent weight loss.

Weighing the Claims

In May 2000 the Partnership for Healthy Weight Management, a coalition of scientific, academic, health-care, government, commercial, and public interest representatives, initiated consumer and media education programs that not only aimed to increase public awareness of the obesity epidemic in the United States but also to promote responsible marketing of weight-loss products and programs. The partnership also published the consumer guide Finding a Weight Loss Plan That Works for You (2005,, which was designed to help overweight or obese consumers find weight-loss solutions to meet their needs. The guide contains a checklist that enables consumers to compare weight-loss plans based on a variety of criteria. (See Table 9.1.) It also advises consumers about how to select weight-loss programs and services based on specific information from potential providers. The coalition also launched the Ad Nauseam (2006, campaign to encourage the media to demand proof before accepting advertising copy that contains unbelievable, dubious, or extravagant promises of weight-loss success.

In Weight-Loss Advertising: An Analysis of Current Trends (September 2002,, Richard L. Cleland et al. of the FTC report that as much as 55% of advertising for weight-loss products and services contains false or unsupported effectiveness claims. Nearly 40% of the three hundred advertisements reviewed by Cleland et al. made at least one assertion that was most likely false, and an additional 15% made at least one representation that was very likely false, or in the best cases, lacked adequate substantiation. Table 9.2 shows the frequency of claims made by various types of weight-loss products and services. Cleland et al. also observe that despite an unprecedented law enforcement effort in the decade preceding their study, the incidence of false and deceptive weight-loss advertising claims appeared to have increased.

On November 19, 2002, the FTC convened a workshop attended by researchers, scholars, media experts, and medical professionals from the government, academia, and private industry that aimed to evaluate claims and develop new and more effective ways to combat false and deceitful weight-loss advertising claims. The FTC summarized the workshop proceedings, including attendees' assessments of eight broad categories of advertising claims, in Deception in Weight-Loss Advertising Workshop: Seizing Opportunities and Building Partnerships to Stop Weight-Loss Fraud (December 2003, The following section considers the advertising claims and summarizes the attendees' assessments of these claims. It also draws on an analysis of the FTC report by Stephen Barrett in ''Impossible Weight-Loss Claims: Summary of an FTC Report'' (December 16, 2003,

No Diet or Exercise Required

CLAIM. The advertised product causes substantial weight loss without exercise or diet.

EXAMPLES. ''U.S. patent reveals weight loss of as much as 28 pounds in 4 weeks. . . . Eat all your favorite foods and still lose weight. The pill does all the work,'' and ''Lose up to 2 pounds daily without diet or exercise.'' Table 9.3 contains other examples of comparable claims.

ASSESSMENT. The consensus was that products purporting to cause weight loss without diet or exercise would either need to cause malabsorption (impair the absorption) of calories or to increase metabolism. Because the number of calories that can be malabsorbed is limited to twelve hundred to thirteen hundred calories per week, or about one-third of a pound per week, malabsorption alone is unlikely to lead to substantial weight loss. Similarly, there is no thermogenic (heat producing) agent, such as ephedrine combined with caffeine, able to boost metabolism enough to produce weight loss without diet or exercise. In fact, the mechanism by which ephedrine products appear to assist weight loss is by suppressing appetite rather than speeding metabolism. Furthermore, even though green tea extract was found to increase metabolism, it was by a scant 4%.

Dietary Supplements
Meal replacement
Plans/programs/diet centers
Trandermal products
Fast results60%59%58%33%43%90%73%42%
Guaranteed results59%93%36%7%24%60%55%42%
No diet or exercise55%56%12%20%14%20%27%33%
Safe/no side effects55%30%27%20%24%50%36%25%
Clinically proven53%036%7%10%40%82%33%
No more failure32%89%27%20%24%20%9%38%
Medical approval34%7%12%7%10%036%38%
Excessive wt. loss warning12%4%005%09%0


Examples of claims that promise weight loss without diet or exercise

"Awesome attack on bulging fatty deposits ... has virtually eliminated the need to diet." (Konjac root pill)

"They said it was impossible, but tests prove [that] my astounding diet-free discovery melts away. . . 5, 6, even 7 pounds of fat a day." (ingredients not disclosed)

"The most powerful diet pill ever discovered! No diet or workout required. The secret weight-loss pill behind Fitness models, Show Biz and Entertainment professionals! No prescription required to order." (ingredients not disclosed)

"Lose up to 30 lbs . . . No impossible exercise! No missed meals! No boring foods or small portions!" (plant extract fucus vesiculosus)

"Lose up to 8 to 10 pounds per week ... [n]o dieting, no strenuous exercise." (elixir purportedly containing 16 plant extracts)

"My 52 lbs of unwanted fat relaxed away without dieting or grueling exercise." (hypnosis seminar)

"No exercise ... [a]nd eat as much as you want—the more you eat, the more you lose, we'll show you how." (meal replacement)

SOURCE: Richard L. Cleland et al., "Table 5. Lose Weight without Diet or Exercise Claims," in Weight Loss Advertising: An Analysis of Current Trends, Federal Trade Commission, September 2002, (accessed November 12, 2007)

No Restrictions on Eating

CLAIM. Users can lose weight while still enjoying unlimited amounts of high-calorie foods.

EXAMPLE. ''Eat All the Foods You Love and Still Lose Weight (Pill Does All the Work).''

ASSESSMENT. This claim was viewed as a variation of the assertion that dieters can lose weight without reducing caloric intake or increasing exercise, because this claim states that users not only can lose weight without reducing caloric intake but also may increase caloric intake and still lose weight. The assembled experts concurred that if this claim was true, it would defy the laws of physics.

Permanent Weight Loss

CLAIM. The advertised product causes permanent weight loss.

EXAMPLES. ''Take it off and keep it off. You won't gain the weight back afterwards because your weight will have reached an equilibrium,'' and ''People who use this product say that even when they stop using the product, their weight does not jump up again.''

ASSESSMENT. Even if a product caused weight loss through a reduction of calories, appetite suppression, or malabsorption, weight would be regained once use of the product stopped and calorie consumption returned to previous levels. Researchers and health professionals have repeatedly observed that dieters tend to regain weight lost over time once the diet, intervention, or other treatment ends. According to the National Academy of Science, Food, and Nutrition Board, ''Many programs and services exist to help individuals achieve weight control. But the limited studies paint a grim picture: those who complete weight-loss programs lose approximately 10 percent of their body weight only to regain two-thirds of it back within 1 year and almost all of it back within 5 years.'' Furthermore, there are no published scientific studies supporting the claim that a non-prescription drug, dietary supplement, cream, wrap, device, or patch can cause permanent weight loss.

Fat Blockers

CLAIM. The advertised product causes substantial weight loss through the blockage or absorption of fat or calories.

EXAMPLES. ''[The named ingredient] can ingest up to 900 times its own weight in fat, that's why it's a fantastic fat blocker,'' and ''The Super Fat Fighting Formula inhibits fats, sugars and starches from being absorbed in the intestines and turning into excess weight, so that you can lose pounds and inches easily.''

ASSESSMENT. Science does not support the possibility that sufficient malabsorption of fat or calories can occur to cause substantial weight loss. To lose even one pound per week requires malabsorption of about five hundred calories per day or about fifty-five grams of fat. To lose two pounds per day, as promised in some advertisements, would require the malabsorption of seven thousand calories per day, which is impossible given that it is several times the total calories that most people consume daily, let alone the number of calories consumed from fat. The FTC has challenged deceptive fat-blocker claims for some of the most popular diet products on the market. The evidence supports the position that consumers cannot lose substantial weight through the blockage of the absorption of fat. It is not scientifically feasible for a nonprescription drug, dietary supplement, cream, wrap, device, or patch to cause substantial weight loss through the blockage of absorption of fat or calories.

Quick Weight Loss

CLAIM. The user of the advertised product can safely lose more than three pounds a week for time periods exceeding four weeks. Table 9.4 shows claims that promise unbelievably rapid results.

EXAMPLES. ''Lose three pounds per week, naturally and without side effects.''

ASSESSMENT. Significant health risks are associated with medically unsupervised, rapid weight loss over extended periods of time. In general, ''the more restrictive the diet, the greater are the risks of adverse effects associated with weight loss.'' One of the best documented risks is the increased incidence of gallstones. The claim that consumers using products such as these can safely lose more than three pounds per week for a period of more than four weeks is not scientifically feasible.

Weight-Loss Creams and Patches

CLAIM. The advertised product that is worn on the body or rubbed into the skin causes substantial weight loss.

EXAMPLES. ''Lose two to four pounds daily with the Diet Patch,'' and ''Thigh Cream drops pounds and inches from your thighs.''

ASSESSMENT. Diet patches and creams that are worn or applied to the skin have not been proven to be safe or effective. Furthermore, their alleged mechanisms of action are not scientifically credible.


Examples of claims that promise fast results

"This combination of plant extracts constitutes a weight-loss plan that facilitates what is probably the fastest weight loss ever observed from an entirely natural treatment." (elixir purportedly containing 16 plant extracts)

"Just fast and easy, effective weight loss!" (fucus vesiculosus)

"Lose 10 lbs. in 8 Days!" (apple cider vinegar)

"Rapid weight loss in 28 days!" (ephedra)

"Knock off your unwanted weight and fat deposits at warp speeds! You can lose 18 pounds in one week!" (ingredients not disclosed)

"Clinically proven to cause rapid loss of excess body fat." (phosphosterine)

"Two clinically proven fat burning formulations that are guaranteed to get you there fast or it costs you absolutely nothing." (ingredients not disclosed)

SOURCE: Richard L. Cleland et al., "Table 4. Representative Claims that Promise Fast Results," in Weight Loss Advertising: An Analysis of Current Trends, Federal Trade Commission, September 2002, (accessed November 12, 2007)

Guaranteed Success

CLAIM. The advertised product causes substantial weight loss for all users.

EXAMPLES. ''Lose excess body fat. No willpower required. Works for everyone no matter how many times you've tried and failed before.''

ASSESSMENT. This claim assumes that overweight and obesity arise from a single cause or are amenable to a single solution. Because the causes of overweight and obesity are thought to be genetic factors and environmental conditions, and contributing factors such as diet, metabolic rate, level of physical activity, and adherence to weight-loss treatment vary, it is unlikely that one product would be effective for all users. Even U.S. Food and Drug Administration-approved, prescription drugs for weight loss have a high level of nonresponders, and surgical treatment for obesity is not successful 100% of the time. The claim that a nonprescription drug, dietary supplement, cream, wrap, device, or patch will cause substantial weight loss for all users is not scientifically feasible.

Targeted Weight-Loss Products

CLAIM. Users of the advertised product can lose weight from only those parts of the body where they wish to lose weight.

EXAMPLES. Testimonial advertising included claims such as ''And it has taken off quite some inches from my butt (5 inches) and thighs (4 inches), my hips now measure 35 inches. I still wear the same bra size though. The fat has disappeared from exactly the right places.''

ASSESSMENT. Small published studies of aminophylline cream indicate that its use may cause the redistribution of fat from the thighs to other fat stores; however, it has not been shown to cause fat loss. Even if some products were capable of causing more weight loss from certain areas of the body, no part would be spared completely—fat is lost from all fat stores throughout the body.

Red Flag Campaign and Big Fat Lie Initiative Target Phony Weight-Loss Claims

Another outcome of the November 2002 workshop was the design of an education initiative to assist the media to voluntarily screen weight-loss product ads containing claims that are ''too good to be true.'' The media were targeted for intensive education not only because broad-based public education has proven largely inadequate to protect consumers from persuasive messages trumpeting easy weight loss but also to acknowledge the media's powerful ability to reduce weight-loss fraud by sharply reducing the dissemination of obviously false weight-loss advertising. On December 9, 2003, the FTC launched its Red Flag campaign to more effectively assist the media to reduce deceptive weight-loss advertising and promote positive, reliable advertising messages about weight loss.

In April 2004 the FTC filed claims against seven companies for making false weight-loss claims, and in November 2004 the FTC announced six new cases against advertisers using bogus weight-loss claims. In each of these cases, the FTC sought to stop the bogus ads and to secure reparation for consumers. The FTC also launched in November 2004 Operation Big Fat Lie, a nationwide law enforcement action against the six companies making false weight-loss claims in national advertisements. Operation Big Fat Lie aims to stop deceptive advertising and provide refunds to consumers harmed by unscrupulous weight-loss advertisers; encourage the media not to carry advertisements containing bogus weight-loss claims; and educate consumers to be wary of companies promising miraculous weight loss without diet or exercise. The FTC also launched a Web site ( to help consumers identify false weight-loss claims.


Even though most Americans are overweight, some people are experimenting with extremely low-calorie diets in the hope that by remaining extremely thin they will stave off disease and live longer. Advocates of extreme caloric restriction (CR) contend that sharply reducing caloric intake creates biochemical changes that slow the aging process, which theoretically should increase life expectancy.

Most people would find it impossible to adhere to semi-starvation diets, but there is sound scientific evidence—such as Luigi Fontana and Samuel Klein's ''Aging, Adiposity, and Calorie Restriction'' (Journal of the American Medical Association, vol. 297, no. 9, March 7, 2007) and Arthur V. Everitt and David G. Le Couteur's ''Life Extension by Calorie Restriction in Humans'' (Annals of the New York Academy of Sciences, vol. 1114, no. 1, October 2007)—that subsistence diets increase the life span of fruit flies, worms, spiders, guppies, mice, and hamsters by between 10% and 40%. In theory, semistarvation prolongs life by reducing metabolism—how quickly glucose is used for energy—in an evolutionary adaptation to conserve calories during periods of famine. Dieters are familiar with this process—they know from experience that as they eat less, their metabolic rate drops, which makes losing weight increasingly more difficult. CR adherents experience comparable drops in metabolic rate—one study found that their body temperature dropped by a full degree. Proponents of CR assert that even though metabolism is vital for life, it is also destructive because it produces unstable molecules known as free radicals that can damage cells through a process called oxidation.

Animal studies find that CR inhibits the growth of cancerous tumors, possibly because at lower body temperatures the body may be better able to repair damaged deoxyribonucleic acid, which provides the genetic information necessary for the organization and functioning of most living cells and controls the inheritance of traits and characteristics. Animals on CR diets have reduced levels of blood sugar and insulin and greater insulin sensitivity, all of which reduces their risk for diabetes and cardiovascular disease. There is even evidence that CR boosts brain function. Mice with the tendency to develop neurological conditions such as Alzheimer's or Parkinson's disease developed these conditions later and more slowly when they were placed on CR diets, and rodents on CR diets displayed better memory and learning than those on normal diets. There is also evidence that CR influences patterns of gene expression. As animals age, certain genes tend to turn off and become inactive, whereas others are activated. In ''Genomic Profiling of Short- and Long-Term Caloric Restriction Effects in the Liver of Aging Mice'' (Proceedings of the National Academy of Sciences, vol. 98, no. 19, September 11, 2001), Shelley X. Cao et al. indicate that CR prevents 70% of change in gene expression in mice.

In 2004 the National Institutes of Health began a seven-year study to explore the effect of CR on human metabolism. The study is exploring the benefits and risks associated with CR. CR adherents report immediate health benefits including increased mental acuity, reduced need for sleep, sharply reduced cholesterol and fasting blood sugar levels, weight loss, and reduced blood pressure. The regimen is clearly not easy, and even its staunchest advocates, such as members of the Caloric Restriction Society, concede that many people who practice CR experience constant hunger, obsessions with food, mood disorders such as irritability and depression, and lowered libido. CR can also cause people to feel cold, and even with adequate vitamin and mineral supplementation it can cause some people to suffer from osteoporosis (decreased bone mass) and hair loss.

In ''Why Dietary Restriction Substantially Increases Longevity in Animal Models but Won't in Humans'' (Ageing Research Reviews, vol. 4, no. 3, August 2005), John P. Phelan and Michael R. Rose challenge the notion that CR will increase longevity. The scientists conclude that severely restricting calories over decades may add a few years to a human life span, but will not enable humans to live to 125 years or older. The investigators developed a mathematical model based on the known effects of calorie intake and life span that showed that people who consume the most calories have a shorter life span, and that if people severely restrict their calories over their lifetime, their life span increases by between 3% and 7%—far less than the twenty-plus years some hoped could be achieved by drastic CR. Phelan and Rose opine that ''longevity is not a trait that exists in isolation; it evolves as part of a complex life history, with a wide range of underpinning physiological mechanisms involving, among other things, chronic disease processes.'' They advise Americans to ''try to maintain a healthy body weight, but don't deprive yourself of all pleasure. Moderation appears to be a more sensible solution.''

Everitt and Le Couteur confirm that even though shortterm CR does improve specific markers associated with longevitysuchasdeepbodytemperature and plasma insulin levels, CR is unlikely to offer markedly increased longevity. The authors cite as evidence the Okinawans, the longest-lived people on earth, who consume 40% fewer calories than the average American and live just four years longer. Everitt and Le Couteur opine that ''the effects of CR on human life extension are probably much smaller than those achieved by medical and public health interventions, which have extended life by about 30 years in developed countries in the 20th century, by greatly reducing deaths from infections, accidents, and cardiovascular disease.''

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Diet and Weight–Loss Lore, Myths, and Controversies

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