The National Heart, Lung, and Blood Institute (NHLBI) is part of the National Institutes of Health (NIH). This section of its Web site provides useful, medically reviewed information about obesity and weight loss.

The Partnership for Healthy Weight Management promotes strategies for achieving and maintaining a healthy weight. It has produced the "Voluntary Guidelines for Providers of Weight Loss Products or Services" (available on its Web site), which can help consumers choose weight-loss programs or products.

The National Institute of Diabetes and Digestive and Kidney Diseases maintains this section of its Web site to provide reliable information on eating disorders, nutrition, obesity, and treatment for obesity. It includes a section on helping an overweight child.

The American Society for Bariatric Surgery provides information on surgery for obesity, including guidelines for surgery and risks and outcomes of surgery. A body mass index calculator is provided, as well as links to other Web sites and organizations concerned with obesity.

Overeaters Anonymous (OA) is a nonprofit international organization that sponsors a 12-step program to help people understand and overcome compulsive eating disorders. OA is not a weight-loss program and makes no claims for weight loss. The program focuses on the psychological and social aspects of overeating.

Shape Up America! is a national coalition of industry and medical experts in nutrition and fitness. Its goals are to make Americans more aware of the importance of maintaining a healthy weight and to provide information about how to lose weight and stay fit. The organization has published several booklets on weight loss and diet, which can be ordered from the Web site.

The Weight-control Information Network (WIN) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health. WIN supplies information on weight control, obesity, and nutritional disorders for the public and for health professionals.