Obesity Many Americans are at increased health risk because they are obese. The U.S. Surgeon General, in a 1988 report on nutrition and health, estimated that one-fourth of adult Americans are overweight. Obesity is a known risk factor for chronic diseases including heart disease, diabetes, high blood pressure, stroke, and some forms of cancer. Everyone needs a certain amount of body fat for stored energy, heat insulation, shock absorption, and other functions. As a rule, women have more fat than men. Doctors generally agree that men with more than 25 percent body fat and women with more than 30 percent body fat are obese. P