Obesity seems to lead to inflammation and impaired insulin function. Exercise can play a quasi-insulin role by stimulating visfatin. The aim of this study was to investigate the effect of 10 weeks resistance training on visfatin and insulin resistance in obese adolescents. In this semi-experimental study, 16 adolescent obese boys with Mean age (17. 93±0. 61) years a body mass index of 30 to 35 kg/m2 were purposefully selected and randomly and equally divided into experimental and control groups. The training group performed a resistance training program with an intensity of 40 to % 851RM, three sessions per week, for ten weeks. Before the start of the training program and 48 hours after the last training session, the values of visfatin, glycemic index and body composition were measured. Data analysis was performed using dependent t-test and covariance analysis at a significance level of P<0. 05. Data analysis showed that after 10 weeks of resistance training, serum levels of plasma visfatin (P=0. 001, F=375. 81), insulin resistance (P=0. 001, F =1967. 87), insulin (P= 0. 001, F= 325. 62, glucose (P= 0. 001, F=66. 99) and fat percentage (P= 0. 03, F= 5. 57) in the experimental group in terms of control. You have less although weight (P=0. 15, F=2. 26) and body mass index (P=0. 20, F=1. 81) were associated with a decrease in intergroup comparison, it was not significant. Resistance training appears to be effective in improving glycemic index and body composition in obese individuals by acting on visfatin plasma and enhancing its insulin-like function.