Effects of obesity treatments on bone mineral density, bone turnover and fracture risk in adults with overweight or obesity

Abstract

Background: New evidence suggests that obesity is deleterious for bone health, and obesity treatments could potentially exacerbate this. Materials and methods: This narrative review, largely based on recent systematic reviews and meta-analyses, synthesizes the effects on bone of bariatric surgery, weight loss pharmaceuticals and dietary restriction. Results and conclusions: All three obesity treatments result in statistically significant reductions in hip bone mineral density (BMD) and increases in bone turnover relative to pre-treatment values, with the reductions in hip BMD being strongest for bariatric surgery, notably Roux-en Y gastric bypass (RYGB, 8%-11% of pre-surgical values) and weakest for dietary restriction (1%-1.5% of pre-treatment values). Weight loss pharmaceuticals (orlistat or the glucagon-like peptide-1 receptor agonist, liraglutide) induced no greater changes from pre-treatment values than control, despite greater weight loss. There is suggestive evidence that liraglutide may increase bone mineral content (BMC) -but not BMD -and reduce fracture risk, but more research is required to clarify this. All three obesity treatments have variable effects on spine BMD, probably due to greater measurement error at this site in

Fracture risk after three bariatric surgery procedures in Swedish obese subjects: up to 26 years follow‐up of a controlled intervention study

“…The mechanisms behind the increased risk of fracture after gastric bypass are not fully elucidated. The increased risk of osteoporotic fracture after gastric bypass in our study suggests that weakening of the bone may play a role, supported by studies demonstrating that gastric bypass is associated with reduction in bone mineral density . It has been suggested that mechanical unloading due to weight loss is a driver of bone loss after bariatric surgery .…”

“…Several studies have shown a reduction in bone mineral density after bariatric surgery and retrospective studies indicate that bariatric surgery is associated with increased fracture risk . However, a small randomized trial found no increased fracture risk for patients receiving bariatric surgery and a recent meta‐analysis on fracture risk after bariatric surgery called for additional high‐quality, prospective studies that investigate fracture risk after bariatric surgery .…”

Severely restricting energy intake for 24 h does not affect markers of bone metabolism at rest or in response to re-feeding

“…The current study also found there was no effect on markers of bone metabolism to feeding the following day. This is important as feeding is critical to the bone remodelling process [8]. As the current study only assessed the postprandial response to the first meal consumed after energy restriction, it is possible that delayed changes occurring in the subsequent hours or days were not captured.…”

“…Nevertheless, weight-loss achieved via continuous energy restriction has been consistently shown to lead to reduced BMD [25]. Issues with dual-energy X-ray absorptiometry (DXA) in participants losing weight [8,27], as well as difficulty controlling exercise [28] and diet composition (e.g. calcium intake) [29], over a 6-month intervention period involving 3-months of self-selected food intake, might help to explain why these results differ from other diet-induced weight-loss studies.…”

“…osteoclastic bone resorption and osteoblastic bone formation). Bone mineral density is dictated by the balance between bone formation and resorption that occurs over time, which is a reflection of the physiological and mechanical environment [8]. Energy restriction is a risk factor for stress fracture incidence [9,10], bone metabolism is markedly disrupted by 3-5 days of energy restriction (i.e.…”