BACKGROUND: Weight loss increases fracture risk in older adults. We aimed to determine associations of two-year body composition trajectories with subsequent falls and fractures in older men.
METHODS: We measured appendicular lean mass (ALM) and total fat mass (FM) by dual-energy X-ray absorptiometry at baseline and Year 2 in 1,326 community-dwelling men aged ≥70 years. Body composition trajectories were determined from residuals of a linear regression of change in ALM on change in FM (higher values indicate maintenance of ALM over FM), and a categorical variable for change in ALM and FM (did not lose [≥-5% change] vs lost [<-5% change]). Bone mineral density (BMD), hand grip strength and gait speed were assessed at Years 2 and 5. After Year 2, incident fractures (confirmed by radiographic reports) and falls were recorded for 6.8 years.
RESULTS: Compared with men who did not lose ALM or FM, men who did not lose ALM but lost FM, and men who lost both ALM and FM, had reduced falls (-24 and -34%, respectively; both P<0.05). Men who lost ALM but did not lose FM had increased falls (incidence rate ratio=1.73; 95%CI 1.37-2.18). ALM/FM change residuals were associated with improved lumbar spine BMD (B=0.007; 95%CI 0.002-0.012 g/cm2 per SD increase) and gait speed (0.015; 0.001-0.029 m/s), and reduced hip fractures (hazard ratio=0.68; 95%CI 0.47-0.99).
CONCLUSIONS: Fracture risk may be increased in older men who lose higher lean relative to fat mass. Weight loss interventions for obese older men should target maintenance of lean mass.