Morbid obesity has become a common condition and there is no effective drug that is able to induce a sustained weight loss. Currently bariatric surgery remains the only effective means that is able to lead to long term sustained weight loss. Oxytocin is a hormone secreted by the hypophysis that regulates negatively the adipogenesis and positively the osteogenesis. Oxytocin also regulates appetite and its role in weight loss in humans has not been investigated so far. The aim of the present study is to elucidate whether plasma levels of oxytocin and sleeve gastrectomy induced weight loss are correlated in pre-menopausal morbidly obese women.

Inclusion Criteria:

• Women aged 18-65, pre-menopausal,
• able to read and understand the written informed consent,
• with a BMI > 40 or 35
• with at least one obesity linked comorbidity among blood hypertension,
• type 2 diabetes,
• sleep apnea syndrome,
• invalidating arthritis,
• indication for sleeve gastrectomy
• accepted by the multidisciplinary committee and the CPAM (local health care system agency),
• affiliation to the Fre,nch health care system,
• signature of the informed consent.

Exclusion Criteria:

• Post-menopausal women,
• any other bariatric procedure that sleeve gastrectomy, history of any other bariatric procedure,
• pregnancy,
• age less than 18 years under, under guardianship
• Patients undergoing any other procedure that the planned sleeve gastrectomy or undergoing a second bariatric procedure for a complications during the 6 months follow-up.