Sermorelin is a human growth hormone-releasing (GHRH) analogue, and also one of the shortest synthetic peptides with full GHRH biological activity. It was initially developed to test the secretion of growth hormone, but was later discovered it acts directly on the pituitary gland to stimulate the production of GH.
Ipamorelin is also a short synthetic peptide (it’s a pentapeptide, meaning it consists of only 5 amino acids), which acts as a ghrelin mimetic and a potent growth hormone releasing agent.
Since ghrelin is a hormone which controls appetite and regulates food intake, ipamorelin is thought to have a weight regulatory property to it. And, when combined with sermorelin is this particular peptide blend, a potent growth hormone secretion effect is noted.