Leptin is a protein that is made in the body's fat cells that balances the body's metabolism and each person has a variable ideal leptin threshold, according to WebMD. Dieting can cause the lost of fat and the loss of leptin production within the body.
Leptin lets the body know that there is enough energy available to function that allows the body to eat, burn energy and exercise at an ideal normal rate, reports WebMD. When leptin levels are below the body's ideal threshold, which varies by individual, the body senses it is in starvation mode. The body compensates for the low leptin levels through the vagus nerve in order to reestablish ideal leptin levels.