Background and Objective: Knowledge of resting metabolic rate and body composition is important for defining appropriate nutritional, energy balance and weight control. The purpose of this study was to compare resting metabolic rate (RMR) and body composition in young sedentary males after aerobic and resistance exercise training. Materials and Methods: Twenty eight sedentary male students were randomly assigned to participate in one of the following groups: endurance program (n=8), resistance program (n=10) and control group (n=10). The exercise training programs consisted of 6 weeks and 3 sessions of aerobic (running, by intensity 65% to 85% of HRmax) and resistance (11 exercises, 3 sets, 10 to 12 repetitions, 65% of 1RM) training per week. Before and after training, resting metabolic rate, body composition and VO‌2max were determined for each participant. Within- group differences were analyzed by using student t-test. One way ANOVA was used for between -group differences. Results: Results demonstrated that RMR increased significantly in resistance training while decreased significantly in endurance training. There was not any significant difference in RMR of the control group (p≤0.05). When RMR was normalized to FFM (kcal.kg FFM-1day-1), there were no significant improvement in RMR for any of the three groups. Total factors involved in body composition decreased significantly at the end of aerobic training. With resistance training, there was a significant decrease in FFM and BMI (p≤0.05). Conclusion: This study indicates that weight loss programs are more dependent on the amount of energy expenditure during the exercises than on the type of training. The findings support that there is not much difference in using aerobic or resistance training to increase resting metabolic rate and weight loss.