Obesity has reached epidemic proportions in the United States: more than 20% of adults are clinically obese as defined by a body mass index of 30 kg/m(2) or higher, and an additional 30% are overweight. Environmental, behavioral, and genetic factors have been shown to contribute to the development of obesity. Elevated body mass index, particularly caused by abdominal or upper-body obesity, has been associated with a number of diseases and metabolic abnormalities, many of which have high morbidity and mortality. These include hyperinsulinemia, insulin resistance, type 2 diabetes, hypertension, dyslipidemia, coronary heart disease, gallbladder disease, and certain malignancies. This underscores the importance of identifying people at risk for obesity and its related disease states.