“Leptin” Leptin is a hormone that is produced by the body’s fat cells. It is often referred to as the “satiety hormone” or the “starvation hormone.” Leptin’s primary target is in the brain, particularly an area called the hypothalamus. Leptin is supposed to tell the brain that we have enough fat stored, that we don’t need to eat, and that we can burn calories at a normal rate. It also has many other functions related to fertility, immunity, brain function and others (5). However, leptin’s main role is long-term regulation of energy balance… the amount of calories we eat and expend, and how much fat we store on our bodies . The leptin system evolved to keep us from starving or overeating, both of which would have made us less likely to survive in the natural environment. These days, leptin is very effective at keeping us from starving. But something is broken in the mechanism that is supposed to prevent us from overeating. Bottom Line: Lep...