Body weight is one of the best predictors of bone density. Low body weight has been associated with low bone mass and increased fracture risk, and high body weight with high bone mass. Furthermore, weight loss has been associated with bone loss and osteoporotic fractures. The strong positive relationship between body weight and bone mass had largely been thought to be due to mechanical loading.

However, this relationship is more complex than simple load bearing or the response of bone to muscle-induced strain. Adipocytes and osteoblasts originate from a common mesenchymal precursor and regulation of fat and bone cells appears to be more closely co-ordinated, through both central and peripheral pathways, than previously realised. Moreover, recent data suggest that obesity may not confer the protective effect against fracture as was once thought, with higher than expected prevalence of fractures in obese children and adults.

Bariatric surgery is associated with significant weight loss and some types of surgery, specifically Roux-en-Y gastric bypass surgery has been associated with significant bone loss although this does not appear to be the case with gastric banding.  Data on gastric sleeve surgery, growing in popularity in Australia, is limited.  However, the degree of weight loss and many of the gut hormonal responses following gastric sleeve surgery are similar to gastric bypass, presenting the possibility that bone health may be adversely affected following this type of surgery.

This talk will discuss some of the complexities surrounding the bone – fat relationship, the available data on bone density and fracture following different types of bariatric surgery as well as present some recent data from a current study on long term bone outcomes following bariatric surgery.