Leg fat mass as measured by dual X-ray absorptiometry (DXA) impacts insulin resistance differently in obese women versus men

OBJECTIVE: To investigate the association between regional fat mass (FM) and insulin resistance and dyslipidaemia in obese women and men.

MATERIAL AND METHODS: Body composition was measured by dual-energy X-ray absorptiometry (DXA) in 109 obese women and 113 obese men. Insulin resistance was measured by (HOMA-IR); insulin sensitivity was estimated by metabolic clearance rate (MCRestOGTT) and insulin secretion by HOMAsecr. Serum lipids were assessed.

RESULTS: In women, leg FM was negatively (favourably) associated with HOMA-IR and cholesterol/HDL-cholesterol ratio (p<0.05). Trunk FM was positively (unfavourably) associated with HOMA-IR. Leg/trunk FM ratio was negatively associated with HOMA-IR (p<0.001), cholesterol/HDL-cholesterol ratio (p<0.001) and triglycerides (p<0.01); positively (favourably) with MCRestOGTT (p<0.01) and HDL-cholesterol (p<0.05). No associations were found in men. In women, multiple regression analysis demonstrated that leg/trunk FM ratio was the only explanatory FM for HOMA-IR and MCRestOGTT (R(2) = 0.23 and R(2) = 0.13, respectively; p<0.001), but postmenopausal status was also of importance (R(2) = 0.23, p = 0.019 and R(2) = 0.29, p = 0.015, respectively).

CONCLUSIONS: Leg FM has a favourable influence on insulin resistance and dyslipidaemia in obese women, but not demonstrated in this cohort of obese men.