Leptin Resistance

Nearly all obese individuals are resistant to leptin, the hormone that signals the brain that our appetites are satisfied and we can stop eating. If you are leptin resistant, when you restrict calories you will continue you to be hungry and your body will tell you to eat, eat, eat! Efforts made several years ago to use leptin in drug form to treat obesity were largely unsuccessful. "The majority of obese people actually have high levels of leptin," explains Kahn, who is a Professor of Medicine at Harvard Medical School. "But they are unable to put it to use."

The reason they were unsuccessful was because these obese people are resistant to the hormone's signal. It's similar to type 2 diabetics who are insulin resistant. In fact, leptin and insulin work together to control the quality of metabolism (also the rate of metabolism). Insulin works mostly at the cell level, instructing the majority of cells whether to burn or store fat or sugar and whether to use that energy for maintenance and repair or reproduction of the cells. This is monumentally important because at the individual cell level, turning on maintenance and repair equates to increased longevity. Turning up cellular reproduction on the other hand, leads to a higher risk of cancer.

As critical as insulin is to your health, leptin may be even more so. New research is revealing that glucose and therefore insulin levels may be largely determined by leptin. Leptin, through the brain and hypothalamus, also controls thyroid levels and body temperature. It also determines the accumalation of visceral fat and the ability to burn fat as indicated by triglyceride levels.