Obesity, which has a prevalence at 15% in France, is a major public health concern. Altered glycemic control and irritable bowel syndrome (IBS) are frequently observed in obese patients and lead to reduce the quality of life. In the last decades, the role of gut microbiota and intestinal permeability has been underlined in obesity, glycemic control and IBS. Interestingly, experimental and clinical data show that glutamine, an amino acid, is able to maintain or restore intestinal permeability in different conditions. We thus hypothesize that oral glutamine supplementation may restore gut barrier function contributing to improve glycemic control and IBS-symptoms. Our project will thus aim to evaluate the effects of 8 weeks - oral glutamine supplementation on glycemic control and IBS symptoms in obese patients in a blinded randomized controlled trial. Placebo group will received protein powder. 55 obese patients will enrolled in each arm and will received oral glutamine supplementation or protein powder (10g t.i.d.) during 8 weeks. Blood and feces samples and intestinal permeability assays will be performed at baseline (w0), after 8 weeks of supplementation (w8) and then after 8 weeks of a wash-out period (w16).

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