Aims and Background: The purpose of the present study was to examine the effect of 12-week aerobic exercising on the serum levels of leptin, testosterone, insulin, glucose, cortisol and growth hormone in obese men. Methodology: A quasi-experimental research method was used. A sample of thirty males (30- 45 years old, BMI of 31.8±2.1 kg.m-2) was randomly divided into experimental (n=15) and control groups (n=15). The experimental group performed an aerobic training for 3 days per week which lasted for 12 weeks. Leptin, testosterone, insulin, glucose, cortisol and growth hormone were measured before and 48 h after the training program. Results: There were no significant differences in the serum levels of insulin, glucose, cortisol and growth hormone after the training. However, leptin and testosterone were significantly lower and higher after the training, respectively. Body weight, body mass index (BMI) and body fat percentage significantly decreased after the training (P<0.05). Concurrently, VO2max (P<0.001) increased following the training. After 12 weeks, changes in the control group were not statistically significant (P>0.05). Conclusion: In obese men, regular exercising can decrease BMI, weight, body fat and serum leptin levels and increase serum testosterone levels. Apparently, increase in the serum testosterone level is not a reason for the decrease in the serum leptin. The levels of cortisol, insulin resistance and growth hormone are not affected by exercising.
