Bone Marrow Fat and Bariatric Surgery-Mediated Bone Loss

Inclusion criteria

Postmenopausal women (defined as last menses >12 months)

• Obesity with a BMI ≥ 35 kg/m²,
• Patients with an indication for bariatric surgery with two surgical techniques, RYGB and SG, but who have never had a bariatric surgery procedure previously,
• Patients who have signed the informed consent.

Exclusion criteria

• History of an osteoporotic fracture 2- Current corticosteroid therapy or corticosteroid therapy within the past 3 months, C-onditions or treatments affecting bone metabolism (breast cancer treated with aromatase inhibitors, malabsorption, stomach cancer, primary hyperparathyroidism, uncontrolled hyperthyroidism…),
• History of radiation therapy to the lumbar spine or the hip being studied,
• Patients on hormone replacement therapy (HRT) or patients already on anti-osteoporotic treatment (bisphosphonates, strontium ranelate, teriparatide, or denosumab) other than calcium and/or vitamin D supplementation,
• Chronic kidney disease with a creatinine clearance (CKD-EPI formula) ≤ 30 mL/min,
• Weight > 160 kg, as the bone densitometer table is limited to this weight for the examination,
• Patients who have previously undergone bariatric surgery,
• Patients with orthopedic implants in both hips or the lumbar spine,
• Individuals unable to give personal consent,
• Individuals under legal guardianship or conservatorship,
• Patients not enrolled in a social security program.
• Any contraindication to MRI: (claustrophobia, patients with a pacemaker/defibrillator, cochlear implant, neurostimulator, or orthopedic implants in the hip, pelvis, or lumbar spine, etc.).