Hunger hormone findings could point to breakthrough on obesity

Medical scientists have identified the first human hormone to stimulate a person's appetite, a discovery that could lead to new treatments for patients with severe weight loss.

Drugs that can block the hormone, which is involved in generating hunger pangs, might also provide doctors with new ways of suppressing the appetite of overweight people, scientists say.

Alison Wren, a research fellow at Hammersmith Hospital and Imperial College in London, said an experiment on human volunteers had shown that the hormone, called ghrelin, was important for regulating food intake.

"Levels of ghrelin are highest in the morning before breakfast and then fall during the day after each meal. No other hormone has been found to stimulate appetite before, although some have been found for appetite suppression," Dr Wren said.

In the "double blind" study, volunteers were given ghrelin injections or a placebo of a simple saline solution and neither they nor the scientists knew on which day they had the hormone until after the experiment was over. Dr Wren said that on the days when the subjects were given ghrelin they ate up to 30 per cent more food.

"It became patently obvious to us and to them whether they had the hormone or the placebo injection," she said.

Even a small increase in calories consumed over a long period can have a big effect on weight. Estimates suggest that a man weighing 75kg (12 stone) will put on an extra 15kg over 10 years by increasing his calorie intake by 1 per cent.

Dr Wren said the immediate practical benefit of the findings would be to give cancer patients ghrelin to help them to recover their appetite. Another area of research would involve blocking the hormone to suppress hunger pangs experienced by overweight people.

"There is little effective medical treatment for obesity and we are very excited to have taken this step towards a future therapy,"Dr Wren said.