Plasma leptin concentrations in lean, physically active males and females in relation to body composition and...

It is well recognized that plasma leptin levels even adjusted to body fat are significantly higher in females than in males. Additionally, physical activity irrespectively of sex is known to affect plasma leptin concentrations. However, the predictors of plasma leptin levels in males and females characterized by similar physical activity were not studied. The aim of the present study was to examine the predictors of plasma leptin concentrations in male and female physical education students not engaged in any specific sport but active due to obligatory studies' program.

A total of 36 subjects (17 males and 19 females) volunteered to participate in the study. Fasting blood was drawn from the antecubital vein for glucose and insulin determination. Fasting insulin resistance index (FIRI) was calculated from insulin and glucose plasma levels. Body fat was assessed using bioelectric impendance method (BIA). Pearson product-moment correlations between log10 transformed plasma leptin concentrations and FIRI, fat mass, percentage of body fat and lean body mass were calculated. Multiple regression analysis was performed to find the best model predicting plasma leptin levels.

In males the only variables affecting plasma leptin concentrations were fat mass (r=0.60; p<0.01) and and the percentage of body fat (r=0.49; p<0.04). In contrast, in females the best model included fat mass, lean body mass and FIRI (adj. R2=0.538; p=0.002).

The results of the current study indicated that the predictors of plasma leptin levels markedly differed in physically active males and females. The only variable predicting plasma leptin concentrations in both males and females was body fatness. In females lean body mass and fasting insulin resistance index (FIRI) together with body fatness markedly contributed to the variations in plasma leptin concentrations.