We all need food to generate energy. Our body uses hormones that circulate in the blood to control our food intake.
Hormone levels change when we lose weight and are also the reason why most of us will regain the weight we lose.
The hypothalamus coordinates the body's system that regulates food intake.
Whether you feel like eating depends on the balance of the activity between these two sets of neurons.
Studies found that diet-induced weight loss is associated with hormone changes that promote weight gain.
After weight loss, leptin levels will decrease. But ghrelin, GIP and pancreatic polypeptide will increase in circulation while PYY and CCK will lower. Most of these changes favour regaining lost weight. These hormonal changes seem to be present for at least one year after weight loss, leading to a constant increase in hunger.