'Fullness' Hormone Suppresses Appetite

Decreases Desire to Overeat for 24 Hours

From the WebMD Archives

Aug. 7, 2002 -- An international team of researchers say they have identified a hormone that reduces the desire to overeat. In a small study, people treated with the hormone ate one third fewer calories than their untreated counterparts.

The hormone -- called PYY3-36 -- is normally released from the digestive tract after eating and then appears to travel to the brain and lessen the desire to overeat. As the number of calories a person eats increases so too does the amount of hormone released.

"This is the natural way that the body turns off the appetite after a meal, and it appears to be quite effective when administered by injection," researcher Stephen R. Bloom says.

In the first step of their study, Bloom and colleagues from London's Imperial College of Medicine showed that injections of the hormone decreased appetite and weight gain in rats and mice. They then showed a similar effect in 12 human volunteers who were not overweight.

The volunteers were given either an injection of the hormone or a placebo two hours before sitting down for a large, buffet meal. Over the next 24 hours, those that received the hormone ate about a third less than those who did not. The findings are reported in the Aug. 8 issue of the journal Nature.

"But it remains unclear whether the hormone can actually help someone lose weight," Bloom says. The researchers also don't know if a pill form of the hormone would cause any side effects.

Still, obesity expert Michael W. Schwartz, MD, of the University of Washington, says he is optimistic that new insights into how hormones influence our urge to eat will soon lead to better appetite control drugs. Schwartz co-wrote an editorial accompanying the study.

"I would say within five years we should be seeing the introduction of drugs that are much more effective than the ones that are now available," he tells WebMD. "In the end there will probably not be one single drug that is effective, but a combination of them."

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© 2002 WebMD, Inc. All rights reserved.

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