NUTritional Impact of a Hypocaloric Hyperprotein Diet Before Obesity Surgery

Inclusion Criteria: * Patient eligible for bariatric surgery (according to HAS criteria) whose sleeve gastrectomy is scheduled * Patient with morbid obesity (BMI ≥ 40) * Age ≥ 18 years and ≤ 65 years * Haemoglobinemia ≥ 12 g/dL in men and ≥ 11 g/dL in women * Patient speaking and understanding French * Adult having read and understood the information letter and signed the consent form * Woman of childbearing age with effective / very effective contraception (Cf. CTFG) (estrogen-progestin or intrauterine device or tubal ligation) prior to surgery and a negative -HCG blood pregnancy test at inclusion, for the duration of the study * Postmenopausal woman: confirmatory diagnosis (non-medically induced amenorrhoea for at least 12 months prior to the inclusion visit) * Patient affiliated with, or beneficiary of a social security (health insurance) category Exclusion Criteria: * Contraindication to bariatric surgery detected during the preoperative assessment * Medical contraindication to a restrictive diet * Type I or II insulin-requiring diabetes * Severe renal insufficiency defined by a blood filtration rate \< 30 mL/min * Person wearing a pacemaker or any other implant with the same functions (cochlear implant, bladder battery, etc.) * Person deprived of liberty by an administrative or judicial decision or person placed under judicial protection / sub-guardianship or curatorship * A history of illness or psychological or sensory abnormality likely to prevent the subject from fully understanding the conditions required for participation in the protocol or to prevent him/her from giving informed consent