ghrelin A peptide hormone secreted by cells in the gastro‐intestinal tract that both stimulates the secretion of growth hormone and regulates feeding behaviour and energy balance by acting on the hypothalamus.

ghrelin (grel-in) n. a hormone produced by stomach cells that acts in the hypothalamus to increase appetite and stimulate secretion of growth hormone. Ghrelin levels are lower in obese individuals (suggesting that the hormone does not stimulate eating) and higher in patients with anorexia nervosa.