To analyze whether enhanced adiposity in females as compared with males is associated with a decreased sensitivity to insulin, a group of healthy normal weight females (n = 13, age 21 +/- 1 years) and males (n = 11, age 23 +/- 1 year, mean +/- SEM) was studied. In each subject, body composition (% fat and % muscle), maximal aerobic power (VO2 max) and whole body insulin-mediated glucose metabolism were measured. The group of women had a higher percentage of fat to total body weight (P less than 0.001) and a lower percentage of muscle (P less than 0.001) than the group of men. The higher percentage of fat in women compared with males was due to enhanced peripheral fat accumulation in the arm and thigh regions. VO2 max levels were comparable in both groups (48 +/- 1 mL/kg/min for women, 53 +/- 2 mL/kg/min for men, P = NS). The rate of glucose metabolism (M) was comparable in women (8.78 +/- 0.74 mg/kg/min), and men (8.31 +/- 0.89 mg/kg/min) when expressed per kilogram of total body weight, but when expressed per kilogram of muscle tissue (Mm), it was 45% higher in women (29.4 +/- 2.4 mg/kg/min) than in men (20.2 +/- 1.6 mg/kg/min, P less than 0.005). Partial correlation analysis indicated that the percentage of fat was inversely related to M and Mm in both women (P less than 0.05) and men (P less than 0.05), but not to percentage of muscle or VO2 max.
Conclusions: (1) Insulin-mediated glucose disposal is inversely related to adiposity in normal weight healthy males and females.(ABSTRACT TRUNCATED AT 250 WORDS)