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Last Updated: Thursday, 19 June, 2003, 13:55 GMT 14:55 UK
Op triggers hunger-killing hormone
obese woman
Surgery can boost production of the hormone
Scientists have found that a hormone that tells people when they are full increases in obese patients after they have had surgery.

The discovery could lead to new drugs to treat obesity and better understanding of who will benefit from surgery and why.

The PYY hormone is released by the gut after a meal to tell the brain to stop eating.

Researchers observed that levels of the hormone were much higher in obese people after they had undergone surgery.

They think the hormone contributed to the patients' average loss of 80lbs after the surgery.

Nutrients

The study was carried out by doctors at King's College London and Hammersmith Hospital.

They looked at female patients who had undergone gastric bypass or gastric banding operations and compared their PYY levels with those of women awaiting surgery.

They measured the amount of hormone in the blood before the women ate a meal, and at 30 minute intervals for 180 minutes after the meal.

The obese patients who had undergone gastric bypass surgery showed an increase of around 150% after they had eaten, compared to a rise of 50% in lean people, which could explain why they no longer wanted to eat as much.

In obese patients who had not yet had surgery, only a tiny increase in the hormone was observed.

The hormone is produced by endocrine cells in the gastro-intestine.

Dr Carel le Roux of Hammersmith Hospital, who worked on the research, told BBC News Online: "One possible mechanism is that, with the gastric bypass operation, you can get the nutrients to the cells much quicker, and they release the hormone much earlier.

"But we found the patients who had had the gastric banding didn't see any change in their hormone levels."

He said it was possible that more knowledge of how the hormone works could lead to drug treatments which could negate the need for surgery.

"But that is a long way away. We have only just started to unravel the mechanism."

And he said the study's findings should not be seen as necessarily directing patients towards bypasses rather than banding operations.

He cautioned: "A gastric bypass is a much more permanent option than banding."

'Much to learn'

Dr Ian Campbell, chairman of the National Obesity Forum, told BBC News Online said the discovery of the hormone opened up many options for treatment.

"It raises a lot of possibilities in its role in appetite suppressant."

But he said there was much more to learn about how hormones influenced appetite.

The research is being presented to the Endocrine Society Meeting in Philadelphia.


SEE ALSO:
Morbid obese to get NHS surgery
19 Jul 02  |  Health
Obesity 'starts in the womb'
30 Mar 01  |  Health


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