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Review sets out why bone is lost during weight loss

Weight loss raises bone turnover and lowers bone mineral density, with greater loss in older and leaner adults and after severe caloric restriction such as incretin mimetics or bariatric surgery.

This review examined the mechanisms behind bone loss during caloric restriction in adults managing obesity. Bone mineral density and bone quality fall, through endocrine, nutritional, mechanical and gut microbiota pathways, with greater loss in older and leaner adults. The authors note that calcium, protein and exercise attenuate it, and that randomised trials of other countermeasures are still needed.

Why it is interesting: Sets out the skeletal cost of weight loss, including after incretin mimetics and bariatric surgery.

Source
Current Osteoporosis Reports, 9 September 2026
Paper
Why Do We Lose Bone During Weight Loss: Can It Be Prevented?
Authors
Shapses SA, McGuire BD
DOI
10.1007/s11914-026-00984-z
Type
Peer-reviewed article
Design
Narrative review of mechanisms and risk factors
Verdict
Refines prior evidence
Driver
Obesity, diabetes and GLP-1
Free full text
Free to read at the publisher
Abstract — the authors' own words, CC BY

Purpose of review

Weight loss is recommended for obesity management, but it also increases bone turnover and reduces bone mineral density (BMD) and bone quality (microarchitecture, geometry, and strength). This review examines mechanisms and the multiple factors that influence skeletal responses to caloric restriction. Recent findings

Bone loss during weight loss likely reflects multiple interacting mechanisms, including alterations in endocrine signaling, impaired calcium absorption, reduced mechanical loading, and alterations in the gut microbiota. The extent of bone loss is further influenced by age, sex, initial body weight, nutrient intake, and method of weight loss, with greater loss in older and lean adults, and after severe caloric restriction, such as with incretin mimetics or bariatric surgery. Current evidence emphasizes the importance of adequate nutrient intake (e.g., calcium, protein, etc.) and exercise as countermeasures to attenuate bone loss. Emerging evidence also suggests that additional countermeasures, including osteoporosis medications and other lifestyle interventions, may affect weight-loss-induced bone loss, and randomized trials are needed. Weight-loss-induced bone loss is multifactorial, involving endocrine, metabolic, nutritional, mechanical, and gut microbiota-mediated mechanisms that remain incompletely understood. These mechanisms influencing skeletal responses to weight loss can inform targeted strategies to preserve bone health and reduce fracture risk during obesity management.

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