Sex-specific differences in plasma branched-chain keto acid levels in obesity.

Obesity was associated with a significant increase in postabsorptive plasma concentrations of the branched-chain keto acids in men but not in women matched for body-mass index and age. Plasma glucose and serum insulin were significantly higher in obese subjects than in nonobese control subjects. Obese women had more adipose tissue than did obese men from the sum of triceps and subscapular skinfold thickness. It is suggested that augmentation in plasma branched-chain keto acids in obesity may reflect insulin resistance and that the apparent differences observed between obese women and men may be due to differences in body composition.