IGF-1 belongs to the peptide family which has a same structure and size as insulin. It is a highly anabolic hormone that is released in the liver as well as in the peripheral tissues in response to the GH so that a new muscle could be built. The main work of IGF-1 is to build new muscle tissues by promoting nitrogen retention and protein synthesis. IGF-1 not only makes muscle fibers bigger, but also makes more of them. IGF-1 has potent effect on fat metabolism and helps the body to burn fat rapidly. It also improves mental functions such as reflexes and learning ability.