Overweight has serious adverse effects on health and longevity. It is associated with elevated serum cholesterol, elevated blood pressure, and non-insulin-dependent diabetes. Overweight also increases risk for gallbladder disease and some types of cancers and has been implicated in the development of osteoarthritis of the weight-bearing joints. The burdens of the health impairments caused by overweight are borne disproportionately by women, the poor, and members of certain ethnic groups. Overweight is multifactorial in origin, reflecting inherited, environmental, cultural, socioeconomic, and psychological conditions. All of these factors combined make it difficult for people to lose weight—and to keep off the pounds they have lost.

Many persons try to lose weight for a variety of reasons, using methods such as caloric restriction, exercise, behavior modification, drugs, or combinations of these methods, with or without medical supervision. Such attempts may be successful in the short term, but most often the weight lost is regained. Repeated weight gain and loss may have harmful physiologic, psychological, and economic effects. Clearly, one diet does not "fit all".

Because of the magnitude of the problem of overweight and the difficulty of weight loss and control, I asked the National Institutes of Health [NIH] to convene an NIH Technology Assessment Conference on Methods for Voluntary Weight Loss and Control. The purposes of the conference were 1) to identify the practices being used to achieve weight loss and control, 2) to evaluate the evidence for the success of various methods for weight loss and control, and 3) to assess the beneficial and adverse effects of weight loss to provide the best possible advice to the public on methods for voluntary weight loss and control. Held 30 March to 1 April 1992, the conference was sponsored by the NIH Nutrition Coordinating Committee and the Office of Medical Applications of Research.

Representative Ron Wyden, Chairman of the Subcommittee on Regulation, Business Opportunities and Energy, which has investigated the commercial weight-loss industry, opened the conference and challenged the participants to build linkages between the science of diet, nutrition, and obesity and the American public. The conference brought together scientists with expertise in obesity, clinical nutrition, nutrition, metabolism, behavior, exercise physiology, and other disciplines; the presentations made by these scientists at the conference are contained in this supplement.

The conference served as a forum for the evaluation of information provided by industry and other sources. It also allowed for audience discussion and public comment. An independent, non-Federal Technology Assessment Panel weighed the scientific evidence and prepared a statement in response to the following key questions:

1. How often and in what ways do Americans try to lose weight?

2. How successful are various methods for weight loss and maintenance? What are the attributes of and barriers to successful weight-loss methods and approaches?

3. What are the benefits and adverse effects in the short, medium, and long term?

4. What are the fundamental principles to be used in selecting a strategy to lose and maintain weight?

5. What are the future directions for research?

The panel's statement, reproduced herein, makes it clear that much additional research must be done to address the problems of weight loss and control. The NIH is committed to pursuing this work as part of a recently established NIH Bionutrition Initiative, which will focus on discovering the scientific bases of what constitutes a nutritious, health-promoting diet. Combined with clinical studies designed to formulate effective methods to encourage individuals to adopt healthful behavior, such as eating a well-balanced diet, exercising regularly, and stopping smoking, the NIH Bionutrition Initiative will identify how various foods interact with the body and ultimately enable us to give the American public safe, reliable guidance about what foods to eat for weight control and optimum health.