SOMATROPIN Human growth Hormone (HGH) is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans. HGH stimulates growth in most body tissues, primarily due to increases in cell number rather than size (hyperplasia). This includes skeletal muscle tissue. The transport of amino acids is also increased, as is the rate of protein synthesis. Human growth hormone itself also stimulated triglyceride hydrolysis in adipose tissue (lipolysis), usually producing notable fat loss.