NSW: People who want more, lacking "fullness" hormone

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NSW: People who want more, lacking "fullness" hormone

By Judy Skatssoon, National Medical Writer

SYDNEY, Aug 8 AAP - People who have difficulty resisting that second or third helpingmay be lacking in a "fullness" hormone that tells them when they've had enough to eat.

The hormone may also help explain the "eyes too big for your stomach" phenomenon.

The hormone, called PYY3-36, is made by cells lining the bowel. After eating, levelsof PYY3-36 rise in the blood.

It is believed the hormone travels to the brain's hypothalamus, where it shuts downthe nerves that trigger eating.

Obesity expert Professor Herbert Herzog of Sydney's Garvan Institute, working withcolleagues in the UK and US, discovered the hormone recently after experiments on mice.

When the receptor for the hormone was removed from the mice, the rodents gorged themselves.

"We generated mice which were missing this receptor and we noticed ... they actuallyeat much more," he told AAP.

An article published in the scientific journal Nature today describes how volunteerswere injected with the hormone and set loose at a free buffet.

After the injection, the volunteers reduced the amount of food they helped themselvesto by a third and ate less for up to 12 hours.

"By injecting normal levels of (PYY3-36) it reduces their hunger feeling and about30 per cent of their food intake," Prof Herzog said.

"Obviously it opens a complete new angle on how you can interfere with food intakeor regulation of food intake."

Professor Herzog said the studies indicated that people who did not get a "fullness"

signal may be lacking in the hormone, although it was not known what may cause this tooccur.

Many other factors were involved in the body recognising that it did not need more food, he said.

He said the next step was to develop a synthetic form of PYY3-36 that could be givento curb appetite and aid weight loss.

However, it was too early to say whether the discovery could pave the way for new treatmentsfor eating disorders like bulimia and anorexia, Prof Herzog said.

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KEYWORD: FULLNESS