Hormone Found to Govern Desire for Food

Treatment with leptin could help fight obesity, study says.

By Steven Reinberg
HealthDay Reporter
Thursday, August 9, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

THURSDAY, Aug. 9 (HealthDay News) -- Leptin, a hormone that helps to control feelings of hunger, also appears to govern the desire to eat, British researchers report.

The finding could lead to new insights into obesity and how to treat the condition, the researchers said.

"This work shows that the rewarding properties of food have strong effects on brain areas concerned with liking and desire, and that the tendency for some people to overeat because they like food is influenced by specific hormones and chemicals in the brain," said lead researcher Paul C. Fletcher, a member of the Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital.

Leptin is produced by fat cells and circulates in the bloodstream to reach the brain, where it acts to reduce hunger and increase the feeling of fullness, according to the report in the Aug. 9 issue of Science.

In the study, Fletcher's team studied two people with a rare genetic disorder and don't produce any leptin. They eat excessive amounts of food --even foods they don't especially like -- and are obese. However, when they were treated with leptin, they ate less and lost weight.

The researchers showed the two patients pictures of various foods while they recorded their brain activity. The scientists found that the pictures stimulated activity in the area of the brain called the striatal regions. These regions are associated with pleasant emotions and desires.

One region in particular, the nucleus accumbens, was highly responsive to pictures of foods that the patients liked, the researchers found.

But when the patients were treated with leptin, the pictures of foods produced a reduced response in the brain. And the response was activated mostly by foods the patients liked and only when they hadn't eaten and were hungry, the researchers said.

"Understanding how brain systems interact with hormones that signal hunger and energy stores will provide us with a more complete picture of factors controlling eating behavior and will hopefully take us beyond some of the prevailing and simplistic assumptions about why some people have difficulties in controlling how much they eat," Fletcher said.