Human growth hormone is a protein hormone that the pituitary gland produces in the human body. It stimulates growth as well as cell reproduction and in supplement form is used to treat children with a hormone deficiency. Children receiving human growth hormone supplements typically respond by growing faster, increasing their strength, and reducing body fat, often without significant side effects. In the past, human growth hormone was extracted from human pituitary glands. Today human growth hormone supplements are also developed synthetically, but not without controversy. As adults, our lifestyle choices can have an enormous impact on the level of growth hormone produced. Diet, exercise, adequate sleep, and stress levels profoundly impact growth hormone and subsequently our ability to build muscle mass and metabolize fat.