Ghrelin is a hormone that is produced and released mainly by the stomach with small amounts also released by the small intestine, pancreas and brain. Ghrelin has numerous functions. It is termed the 'hunger hormone' because it stimulates appetite, increases food intake and promotes fat storage. Ghrelin has been investigated for the treatment and basic science of Cancer, Alcoholism, Metabolism, Hypopituitarism, and Frailty Syndrome, among others.