Detraining is known to increase the obese degree, decrease homeostasis of blood glucose and testosterone concentration. This study was aimed to examine the effect of detraining on obese degree, blood glucose levels and testosterone concentration in athletes with different BMI values. Twenty male players consisted of 2 groups, lean and obese (ten in each group) were participated in this study, and all subjects were detrained for 1-month. In both groups body weight, high, waist, hip, total calorie intake, serum testosterone concentration and insulin sensitivity were measured along with oral glucose tolerance test (OGTT). Results of this study: Insulin sensitivity was higher in lean subjects than obese before and after detraining. Although testosterone concentration was higher in lean group before detraining, this was not observed after detaining. Detraining significantly increased the obese degree, decreased the blood glucose homeostasis and testosterone concentration in the lean group. In addition, total calorie intake and triglycerides were higher in the obese group compared to lean group after detraining. Conclusion of this study: This data concludes that obese people have more chance to have physiological disorders than lean people after detraining. This result suggests that obese athletes required continuous regular exercise to attenuate obesity related problems.