The Role of Leptin in Weight Loss

Aug. 7 -- How can three family members slim down to half their body weight without even trying? With the help of an appetite control hormone called leptin, new research suggests.

Leptin, from the Greek "leptos" meaning thin, strives to live up to its name. The hunger hormone "has far-reaching physiological effects on both food intake and energy expenditure," says Dr. Steven Heymsfield, a professor of medicine at Columbia University in New York City.

Manufactured in the fat cells, leptin tells the brain whether the body has sufficient energy stores, or fat. The hormone sends satiety signals to the hypothalmus — the brain's eating control center — and tells us when we can stop eating, explains Dr. Julio Licinio, a professor of psychiatry and medicine at the University of California Los Angeles School of Medicine.

Everyone possesses leptin. Everyone except for Bayrum Donsek, Elif Fakili, and Zeynep Fakili. These three cousins from Turkey are the only known adults in the world to possess the genetic mutation that renders them leptin-deficient — and the consequences have been devastating.

In the absence of leptin, the brain never receives the message that the body has sufficient food, believing it to be in a constant state of starvation. For this reason, the Turkish family members have demonstrated voracious appetites, eating and eating themselves up to weights ranging from 235 pounds to more than 300 pounds, yet never feeling full.

Licinio flew the relatives from their isolated village to the University of California Los Angeles to participate in clinical trials funded by the National Institutes of Health. Everyday for the past 10 months, the cousins have received leptin injections while researchers have tracked every system in their bodies to record the effects of the hormone injections.

The results have been dramatic. So dramatic that the same individuals who required two seats each for their journey to America will soon return home in the regular one seat each.