Aims: Body composition is associated with bone mineral density, but the precise associations between body fat distribution and bone mineral density (BMD) remain unclear. We hypothesised that the regional adipose tissue depots would have independent associations with BMD.
Methods: We used data from 4900 healthy individuals aged 3050 years old from the Oxford Biobank to analyse associations between regional fat mass and lean mass with total BMD.
Results: Lean mass was strongly positively associated with BMD. After adjustment for relevant confounders, total body fat was significantly positively associated with BMD in lean, but not obese, men and women. An overall positive association was observed between total BMD and all fat depots measured either by anthropometry or DXA when accounted for lean mass. However, on mutual adjustment with both total fat and lean mass, both android fat (sβ=−0.360, P=7.80×10−05) and visceral adipose tissue (VAT; sβ=−0.144, P=2.41×10−04) showed directionally opposite effect; a significant decrease in total BMD was observed with increasing android fat and VAT in men while in women only VAT was significantly associated with lower BMD (sβ=−0.151, P=1.72×10−07). Directionally similar association was also observed with waist circumference in men (P=0.001). Most of these associations, except for VAT in women, were not significant when adjusted for HOMAIR.
Conclusions: These results show that the distribution of fat alters the association between adiposity and BMD, possibly mediated by its effect on insulin resistance.