Obesity is a major public health as well as economic (expense of treating) problem world-wide, and Roux-en-Y gastric bypass (RYGB) and Sleeve Gastrectomy (SG) surgeries are effective treatments. A barrier to progress is that between 25% and 40% patients were not successful in achieving and maintaining at least 30% weight loss, which is considered medically successful for this operation. Understanding the mechanisms that contribute to success or failure of this operation is an unsolved problem in obesity research which this proposal is addressing. The focus of this project is to identify mechanisms that contribute to suppression of food intake following bariatric surgery, and to investigate whether these mechanisms predict long term success following bariatric surgery