Ghrelin, the “hunger hormone”, also known as lenomorelin (INN), is a peptide hormone produced by ghrelinergic cells in the gastrointestinal tract, which functions as a neuropeptide in the central nervous system. When the stomach is empty, ghrelin is secreted. When the stomach is stretched, secretion stops. It acts on hypothalamic brain cells both to increase hunger, and to increase gastric acid secretion and gastrointestinal motility to prepare the body for food intake.