Adaptation of Human Gut Microbiota to Energetic Restriction

Gut microbiota ecology is altered in obesity and could link obesity and its complications. Bariatric surgery enables a major and sustained weight loss therefore improving obesity related disease. the investigators primary aim is to evaluate gut microbiota adaptation to weight loss and the specific role of energetic restriction. Furthermore we aim to compare gut flora of obese patients post bariatric surgery to that of lean healthy volunteers. Thus, the investigators plan to compare gut microbiota from 140 obese individuals before and after either restrictive (gastric banding) procedures or gastric bypass procedures to that of 40 lean healthy volunteers at baseline.