Fat and Bone: Where are We Now?

Excerpt

For decades there has been a debate about the impact of adiposity on the skeleton and we have by no means reached a conclusion. This exciting area has moved forward considerably, in part driven by a profound increase in the prevalence of obesity and osteoporosis. Initial clinical observations and studies with DXA suggested that obesity was osteoprotective, at least in adults [1, 2]. More recently it has been suggested that obese adults are more prone to fracture which may be confined to specific skeletal regions [3]. However, the increased risk of fracture in obese children implied that the impact of obesity on bone was age-dependent. This led to a number of studies examining the relationship between childhood obesity and bone with conflicting results, with some suggesting a positive relationship between adiposity and bone with others suggesting that excess fat is detrimental to the developing skeleton [2]. The issue of ‘obesity’ and the effect on the developing and adult skeleton was perhaps considered overly simplistic and subsequent work focusing on fat distribution demonstrated that, as with other metabolic conditions, it is visceral fat that appears to have a deleterious effect on the skeleton [4, 5] although again not all studies in adults are in agreement with this [3]. The advent of high resolution pQCT (HR-pQCT) has allowed us to examine the in-vivo relationship between fat and bone at a microstructural level in children with results demonstrating that the trabecular architecture is more likely altered in response to obesity [6], although from cross sectional studies in adults that may not be the case [7]. Thus, the debate relating to the impact of obesity on the skeleton lives on. In this Special Edition of ‘Fat and Bone’, Farr, Dimitri and Walsh address the past and current research relating to the impact of obesity on bone in children and adults. …