Roux-en-Y gastric bypass (RYGB) surgery is a highly effective treatment for obesity but can have damaging effects on bone mass and microarchitecture as early as 6 months postoperatively, with postmenopausal women being at highest risk, according to a study published in the Journal of Bone and Mineral Research.

Imaging limitations have hindered previous studies on the skeletal effects of RYGB and most have been conducted in modest size samples of premenopausal women and very few men.

Researchers in San Francisco examined 48 obese adults (27  premenopausal women, 11 postmenopausal women, and 10 men) 6 and 12 months after RYGB surgery using spine and hip dual-energy x-ray absorptiometry, spine quantitative computed tomography, radius and tibia high resolution peripheral quantitative computed tomography, and laboratory evaluation.

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Harmful effects of RYGB on bone turnover, mass, structure, and strength were observed 6 months postoperatively and continued through 12 months. They also found that postmenopausal women not only had lower bone mass preoperatively than premenopausal women and men, but they also demonstrated greater changes in skeletal health parameters, including larger increases in serum collagen type 1 C-telopeptide, declines in bone mineral density (BMD), and changes in bone microstructure.

Limitations of the study include the 12-month duration as longer-term skeletal effects of RYGB were not assessed. In addition, although this was the largest study to date to assess axial and appendicular volumetric BMD and appendicular bone microarchitecture and strength, future studies should include larger groups of postmenopausal women and men.

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The investigators concluded that “detrimental effects of RYGB on axial and appendicular bone mass and microarchitecture are detectable as early as 6 months postoperatively. Postmenopausal women are at highest risk for skeletal consequences and may warrant targeted screening or interventions.”


Schafer AL, Kazakia GJ, Vittinghoff E, et al. Effects of gastric bypass surgery on bone mass and microarchitecture occur early and particularly impact postmenopausal women [published online December 27, 2017]. J Bone Miner Res. doi:10.1002/jbmr.3371