Inclusion Criteria:  Patients aged from 18 to 65 years Patient with h grade II or III obesity (body mass index equal or higher than 35 kg/m2) Patient with insulino-resistance (fasting glycaemia ≥ 1g/l et < 1.26 g/l) Patient with irritable bowel syndrome (Rome IV criteria ≥ 2)  Exclusion Criteria:  Patient with Known liver insufficiency (prothrombin time < 70%) Patient with Known kidney failure (GFR < 60 ml/mn) Patient with Known intestinal diseases such as inflammatory bowel diseases Vomiting patients (≥ 1/ day) during the last 4 weeks Patient Previously received bariatric surgery or digestive surgery Patient Using laxatives or protein powder during the 4 last weeks On going Pregnancy