Weight change and risk of fracture in postmenopausal women

The skeleton adapts to changes in mechanical loading, altering its mass and structure to modify bone strength.1 Bone mineral density is positively related to body mass index (BMI), and alterations in body weight are accompanied by changes in bone mass that reflect the new loading environment. Low BMI is a well recognised risk factor for fracture, but obesity also increases the risk of fracture at some sites.2

A linked paper by Crandall and colleagues (doi:10.1136/bmj.h25)3 confirms and extends previous studies that showed that weight loss in postmenopausal women increases the risk of hip and other fragility fractures.4 5 6 7 In over 120 000 postmenopausal women followed for a mean of 11 years, weight loss of ≥5% between baseline and year three was associated with a 65% increase in incident hip fracture, 9% increase in upper limb fracture, and 30% increase in central body fracture (hip, pelvis, or spine) compared with women in whom weight was stable. Both unintentional and intentional weight loss were associated with increased risk, although this differed between sites. The risk of hip and vertebral fracture was increased in women with …