MK-677 or Ibutamoren, promotes the secretion of growth hormone and greatly increases insulin-like growth factor (IGF-1), without increasing cortisol. Both growth hormone and IGF-1, in turn, increase muscle mass, muscle strength, bone density, and reduce body fat. MK-677 has been shown to increase IGF-1 levels even more so than GH itself as well as extend the duration of IGF concentrations in the body.