This study aimed to identify the relationship of fat mass on rate of energy consumption and fat burning during physical effort for men by identifying the fat mass of The research sample by measuring body composition by a Body composition analyzer apparatus and to identify energy consumption and fat burning during physical effort by measuring use apparatus (ERGOSPIROMETRY ZAN 680), and test application (Polk and others) on the apparatus. Research used the descriptive method and the sample was selected among graduates of the
faculty of physical education –mansoura university-Egypt and partitioners of physical activities (n=14) classified in two groups the first fat percentage 3-5% of weight and the second fat percentage >5% of weight. were analyzed the data statistically using the statistical program spss and calculate the averages, the average level, the total level, the value of Mann Whitney test and the pearson correlation significance. the results showed that no significant differences statistically significant between the two groups in most measures of research variables. The study recommended further studies on the communities different sports and
larger samples in terms of number, and the need to make these measurements at the players different sports clubs.