 LOSS is a pragmatic clinical evaluation of intensive medical approaches to weight loss for individuals with extreme obesity body mass index BMI 40-60 kgm2. The intensive medical treatment is designed to produce 25 weight loss from baseline and to maintain at least 20 weight loss from baseline. The intensive medical treatment is compared to a usual care treatment model where individuals utilize self directed approaches to weight loss. The active treatment period is three years, followed by two years of observation. 