The present invention relates to a new use of TRIM72 as a target for muscle enhancer and heart enhancer, more particularly to a composition for enhancing muscle or heart comprising an expression or action inhibitor of TRIM72 protein. The present invention further relates to a new TRIM mutant protein inducing muscle differentiation and hypertrophy and its gene. The inventors of the present invention have identified that TRIM72 overexpression inhibits myogenesis whereas TRIM72 knockdown enhances myogenesis, and first elucidated that TRIM72 is a negative regulator of skeletal muscle differentiation. Accordingly, the inhibition of TRIM72 acts exclusively on skeletal muscle and heart muscle, but does not affect IGF-I signaling pathway in other tissues. Therefore, a drug or gene therapy using TRIM72 as a target may be helpful in treating obesity and type 2 diabetes by promoting skeletal muscle differentiation, hypertrophy and energy consumption in adipose tissue and inducing strong muscle by promoting physiological hypertrophy of heart muscle, without cancer or other side effects.