Protein Need and Interest of " Quick Proteins " to the Obese Subject Operated by Bariatric Surgery (BIBOP)

This is a prospective longitudinal study of the effect of bariatric surgery on protein requirements and protein metabolism, and protein supplementation interest, appropriate to the digestive tract changes, for the mass and muscle function. Three groups of patients will be studied: One group undergoing sleeve gastrectomy in Clermont-Ferrand (group 1: n = 20) will be followed by current recommendations. A second group undergoing sleeve gastrectomy in Clermont-Ferrand (group 2: n = 20) will receive during three months, protein supplement (powder whey protein ("fast")) at dose of 40g / day. 10 patients in group 1 and 10 patients in group 2 will participate in protein metabolism study. The third group undergoing gastric bypass in Lyon (group 3: n = 20) will be followed by the current recommendations and will participate in study of endotoxemia.