We investigated the effects of testosterone on the improvement of white adipose tissue explant and its molecular mechanism in adipose tissue of high fat diet-fed male castrated (CAST) mice. The CAST mice treated with testosterone had lower adipose tissue weights, the average size of adipocytes and mRNA levels of $C/EBP{alpha}$ as well as adipocyte marker genes than the vehicle-treated CAST mice. These results suggest that testosterone prevent the expression of $C/EBP{alpha}$ and $C/EBP{alpha}$-mediated adipocyte marker genes, resulting in decreased adipose tissue mass and adipocyte metabolism in male CAST mice. Moreover, this study give a valuable molecular and biological knowledge on testosterone therapy in obese hypogonadal men.