The prospective, controlled Swedish Obese Subjects study enrolled 4047 subjects who either underwent bariatric surgery or received conventional treatment. The results of follow-up for up to 15 years suggest that bariatric surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. The results suggest that bariatric surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. In the United States from 1980 through 2004, the prevalence of obesity — defined as a body-mass index (BMI) (the weight in kilograms divided by the square of the height in meters) of 30 or more — doubled, rising to include more than 30% of the population. 1 , 2 The majority of large and long-term epidemiologic studies have indicated that obesity is associated with increased mortality. 3 – 9 The life expectancy of severely obese persons is reduced by an estimated 5 to 20 years. 10 Weight loss is known to be associated with improvement of intermediate risk factors for disease, 11 suggesting that weight . . .