Leptin may be a cell-signalling secretion very important within the regulation of appetency, food intake and weight. Studies have shown that associate absence of leptin within the body or leptin resistance will cause uncontrolled feeding and weight gain. Although regulation of fat stores is deemed to be the primary function of leptin, it also plays a role in other physiological processes as evidenced by its many sites of synthesis other than fat cells and the many cell types beyond hypothalamic cells that have leptin receptors.