Long-Term Problems with Weight-Loss Programs
Being overweight can seriously affect health and longevity. It is associated with elevated serum cholesterol, elevated blood pressure, and noninsulin-dependent diabetes mellitus. Excessive weight also increases the risk for gallbladder disease, gout, coronary heart disease, and some types of cancer and has been implicated in the development of osteoarthritis of the weight-bearing joints.
The underlying causes of obesity are unknown. The basic mechanism is an imbalance between caloric intake and energy expenditure, but why this imbalance occurs is unclear. Evidence suggests that obesity is multifactorial in origin, reflecting inherited, environmental, cultural, socioeconomic, and psychological conditions. Increasing physiologic, biochemical, and genetic evidence suggests that obesity is not a simple problem of will power, as is sometimes implied, but is a complex disorder of appetite regulation and energy metabolism.
Many people have a chronic tendency for becoming overweight that needs lifelong attention. Many people attempting to lose weight use methods such as dieting, exercise, behavior modification, drugs, or combinations thereof, with or without medical supervision. Some attempts may be successful in the short term, but too often the weight loss is regained. Repeated weight gain and loss may have adverse psychological and physical effects.
To evaluate methods for voluntary weight loss and control, the National Institutes of Health (NIH) Nutrition Coordinating Committee and the Office of Medical Applications of Research recently held a technology assessment conference, which brought together a panel of scientists with expertise in obesity, clinical disciplines, nutrition, metabolism, epidemiology, biostatistics, behavior, exercise physiology, and other disciplines.
Evidence for diet, exercise, behavior modification, and drug treatment was considered. Information from industry and other sources was evaluated, and opportunity was provided for public comment. The following article reports on the panel's findings.
For most weight-loss methods, there are few scientific studies evaluating their effectiveness and safety. The available studies indicate that people lose weight while participating in such programs but, after completing the programs, tend to regain the weight over time. Further, there are examples where weight-loss strategies have caused medical harm. Thus, before individuals adopt any weight-loss program, the scientific data on effectiveness and safety should be examined. If no data exist, the panel recommends that the program not be used. The lack of data on many commercial programs advertised for weight loss is especially disconcerting in view of the large number of Americans trying to lose weight and the over $30 billion spent yearly in America on weight-loss efforts. Some research data and considerable anecdotal information support successful short-term loss for some users of these programs; however, data are limited on the proportion of people who complete programs, how much weight they lose, and their success in maintaining the weight loss.
Considerable diversity in response exists within each of the broad categories of weight-loss strategies. Success rates can be expected to vary according to initial weight, the length of the treatment period, the magnitude of weight loss desired, and the motivation for wanting to lose weight. The effectiveness of unsupervised efforts to lose weight is difficult to judge because of limited data on strategies, compliance, and follow-up. Surveys indicate that many over-weight people have tried to lose weight on multiple occasions; because many of these people presumably are using these unsupervised strategies, their long-term success rates may be low.
Dietary Change. Dietary change is the most commonly used weight-loss strategy. Methods range from caloric restriction to changes in dietary proportions of fat, protein, and carbohydrate or use of macronutrient substitutes. …