IGF-1 Long R3, or IGF-1 LR3, is a form of IGF that has been chemically altered with changed amino acids. It consists of 83 amino acids with a substation of Arg(R) for the Glu(E) at position three, hence, the name R3. The altercations enable it to avoid binding to proteins in the body, which allows it to have a longer half-life. IGF-1 LR3 is more potent than the regular IGF-1 because of the decreased binding of Long R3 IGF-1 to IGF binding proteins. Its main purpose is to increase the biological activity of IGF. Essentially, when IGF-1 LR3 is active in the body, it functions differently in different types of tissues. For instance, in muscle tissue, it makes the muscle more sensitive to insulin’s effects, such as a reduction in fat storage. But while IGF-1 LR3 helps fat reduction, a person using it will experience weight gain because of the increase in pure-muscle weight.