Bariatric surgery leads to bone loss and increases fracture risk. This study evaluates whether denosumab can prevent the high-turnover bone loss that occurs after Roux-en-Y Gastric Bypass (RYGB) and sleeve gastrectomy (SG) surgery.

Bariatric surgery is a highly effective weight loss treatment, but one of the unintended side effects of these procedures is high-turnover bone loss and metabolic bone disease. Denosumab is a monoclonal antibody to RANKL that acts as a potent inhibitor of bone resorption. The investigators are conducting a randomized placebo-controlled trial to evaluate the ability of denosumab to prevent bone loss after RYGB or SG surgery in older adults. At the conclusion of the study, all participants will be given zoledronic acid.

Inclusion criteria:

• Postmenopausal women who are planning RYGB or SG surgery
• Men aged ≥ 50 years who are planning RYGB or SG surgery

Exclusion criteria:

• Prior bariatric surgery
• Weight = 400 lbs (due to limitations of bone imaging equipment)
• Renal disease
• Hypercalcemia or hypocalcemia
• Hypomagnesemia
• Serum 25-OH vitamin D (25OHD) < 20 ng/mL
• Hyperparathyroidism
• Liver disease (AST or ALT > 2 x upper normal limit)
• HCT < 32%
• History of malignancy (except basal cell carcinoma) in the past 1 year
• Significant cardiopulmonary disease
• Major psychiatric disease
• History of celiac disease or inflammatory bowel disease
• Excessive alcohol or substance abuse
• Paget's disease, primary hyperparathyroidism, or any other known congenital or acquired bone disease other than osteoporosis
• Current hyperthyroidism or use of levothyroxine with TSH < 0.1 uIU/mL
• Current use of loop diuretics
• Current use or use in the past 12 months of oral bisphosphonates or DMAB
• Current use or use within the past 3 months of SERMs or calcitonin
• Current use or use within the past 3 months of estrogen
• Use of testosterone therapy if dose has changed within the last 3 months, or if dose change or discontinuation is planned in the upcoming 18 months
• Any current or previous use of teriparatide, strontium, or any parenteral bisphosphonate
• Use of oral or parenteral glucocorticoids for more than 14 days within the past 6 months
• Extensive dental work involving extraction or dental implant within the past 2 months or planned in the upcoming 18 months
• DXA BMD T-score of < -3.0 at PA spine, total hip, or femoral neck
• Current use of anti-VEGF drug

Baseline to 19 months