Ghrelin is created by the stomach and is known as a peptide released by endocrine cells commonly found in the lining of the stomach. Ghrelin is responsible for sending a message to the brain activating hunger while deactivating the satiety cell. It neutralizes leptin to increase metabolic efficiency to stimulate a person's appetite. When your stomach starts growling, it produces ghrelin. However, the other hormone from fat cells is responsible for creating leptin, which acts as a regulator, but does just the opposite of the hormone ghrelin: it activates the satiety cell and deactivates the hunger cell. In obesity, fat cells become more numerous, leading to high levels of leptin. However, a combination of obesity and high insulin levels can cause the stomach cells that produce ghrelin to shut down, reducing ghrelin levels. Over time, a high level of leptin can lead to satiety cells becoming insensitive to leptin, which decreases ghrelin levels, causing hunger cells to become hypersensitive to ghrelin. Although leptin levels are high and ghrelin is low, hunger cells are on while satiety cells are off (NCBI).,