Leptin is made by adipocytes (fat cells) and has an effect on the brain – an area called the hypothalamus and affects hunger and energy use.

Leptin is an important hormone in periods of inadequate food intake. Leptin levels go down when we fast or are on a low calorie diet and stimulate hunger whilst making sure we expend less energy (store more fat). So, low levels occur when there isn’t much food around, stimulating us to eat and to store the calories as fat.

However the more fat stores we have, the higher levels of leptin. This should mean that we feel less hungry and burn more energy.  There is a theory that obese/overweight individuals, or individuals with hyperinsuinaemia, may be leptin resistant. When we are leptin resistant; the leptin doesn’t bind to its receptors properly and so the body thinks that there are low levels of it- stimulating hunger and storage of body fat.