Ibutamoren, also known as MK 677 and Nutrobal, is a substance that increases the levels of Human Growth Hormone (hGH) in the body. It is illegal to possess ibutamoren without authority. While it’s marketed online as a substance to ‘build muscle’, ibutamoren is technically considered a poison, is banned in sport and has a range of dangerous side effects. Reported side effects include increased appetite, swelling, anxiety, numbness and muscle pain. It also causes bone mineral density to decrease and causes increased fasting blood glucose and decreased insulin sensitivity.