HGH promotes and increases the synthesis of new protein tissues, such as in muscle recovery or repair. This is the way new muscle is built. Recent research suggests its involvement in the metabolism of body-fat and its conversion to energy sources. Tests were conducted in obese people and medical use in treating obesity was proven beyond a doubt. Pro's have used HGH as a way of maintaining and increasing lean mass while dieting for years. It improves the sleeping pattern, makes for less unintended awakenings and betters REM-stage sleep.