Context: There are limited comparative studies between one anastomosis gastric bypass (OAGB) versus Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on body composition and musculoskeletal health.

Objective: To compare changes in body composition, areal bone mineral density (aBMD), muscle strength, and physical function in the first year following OAGB, RYGB and SG within a UK-based healthcare setting.

Methods: This is a secondary analysis of the BARI-LIFESTYLE trial in 119 adults (77% women; mean±SD, age: 45.9±10.3 years; BMI: 43.6±5.5 kg/m2) who underwent OAGB (n=19), RYGB (n=39) and SG (n=61). Body composition and aBMD by dual energy x-ray absorptiometry, handgrip strength, sit-to-stand (STS) test and 6-minute walking test (6MWT) were assessed pre-surgery and at 12 months post-surgery.

Results: OAGB, RYGB, and SG exhibited similar reductions in body weight, body fat and lean mass (within-group comparisons, p<0.001). All surgery types were associated with reductions in aBMD at the total hip, femoral neck, and lumbar spine, which were more pronounced after OAGB and RYGB compared to SG (all p<0.03), though no difference between OAGB and RYGB. Despite reductions in absolute handgrip strength, relative handgrip strength, STS test and 6MWT improved post-surgery (all p<0.02), with no differences by surgical procedure.

Conclusion: OAGB, RYGB, and SG resulted in comparable weight loss, changes in body composition and improvements in relative muscle strength and physical function. OAGB and RYGB, compared with SG, led to greater BMD reductions at clinically relevant sites. Future long-term studies should explore whether these BMD reductions translate into a greater fracture risk.