From both societal and payer perspectives, the economic effect of obesity in the United States is substantial, estimated at approximately 6% of our national health expenditure and cost of care in a major health maintenance organization. The number of physician visits related to obesity has increased 88% in a 6-year period. The morbidity cost (lost productivity) and functional capability of the patient with obesity is increasing rapidly (50% increase in lost productivity, 36% increase in restricted activity, and 28% increase in number of bed-days). Cost savings of treating obesity are comparable to those of treating other chronic diseases such as coronary heart disease and diabetes. Most studies indicate that most of the direct health care costs of obesity are from type 2 diabetes, coronary heart disease and hypertension. To date, however, there have been no published reports of the cost effectiveness of the medical management of obesity treatment. In conclusion, the cost of obesity is comparable to that of other chronic diseases, yet it receives disproportionately less attention. Cost effectiveness studies need to be initiated promptly.