Human growth hormones (HGH) play an important role in normal human growth and development. The major human growth hormone is a protein made up of 191 amino acids, the building blocks of proteins. The production of this protein is controlled by two other hormones secreted by the hypothalamus: growth hormone releasing hormone (GHRH), which controls secretion of human growth hormone (HGH); and growth hormone-inhibiting hormone (GHIH), which inhibits secretion of human growth hormone (HGH). All healthy individuals have measurable levels of hGH throughout life, but there are two notable growth spurts, one at birth and the other at puberty, and hGH plays a vital role at each time. The most obvious effect of human growth hormone (HGH) is on linear skeletal growth (height), but metabolic effects of hGH (the results of hGH activity in the body) on muscle, the liver, and fat cells are a critical part of its function. When any question arises about growth or development, pediatricians may investigate the levels of the major human growth hormone (HGH), its receptors and stimulants, the glands that produce the hormones, and the complex hormone interactions that control normal development. mino acids are biologically important organic compounds. Reference
A Stanford University School of Medicine meta-analysis of clinical studies on the subject published in early 2007 showed that the application of GH on healthy elderly patients increased muscle by about 2 kg and decreased body fat by the same amount.  However, these were the only positive effects from taking GH. No other critical factors were affected, such as bone density, cholesterol levels, lipid measurements, maximal oxygen consumption, or any other factor that would indicate increased fitness.  Researchers also did not discover any gain in muscle strength, which led them to believe that GH merely let the body store more water in the muscles rather than increase muscle growth. This would explain the increase in lean body mass.