Obesity is one of the most important public health problems today. An estimated 65% of US adults are overweight or obese,1 with 112 000 to 280 000 annual deaths attributable to obesity.2,3 If trends continue, obesity-related deaths may lead to cessation of the increases seen in life expectancy and perhaps to reduced life expectancy in the future,4 and obesity will contribute even more adversely to the population's well-being and health care costs in the United States.5