The epidemic of obesity in America shows no sign of abating. In contrast to a favorable secular trend in other coronary risk factors, the prevalence of obesity continues to escalate in the United States.1,2 At present, one quarter to one third of US adults are overweight,3 and at least 34 million can be classified as obese, defined as the equivalent of weight 20% or more above desirable levels.4 Women and minorities, including African Americans, Hispanics, American Indians, and Pacific Islanders, are at particular risk of obesity.5 The prevalence of obesity in the United States is higher than that in Canada, Europe, Australia, and most other regions.6 The relative contributions of cultural and economic factors, educational attainment, diet, physical activity patterns, parity levels, and differences in perceptions about health risks are unclear and require elucidation. Although obesity commonly emerges in traditional societies See also p 1747.