One in five adults in the UK is obese

The Imperial College London team are developing a drug based on a natural gut hormone that mimics the body's "feeling full" response.

An injectible treatment could be available in five to eight years, but the long-term goal is to produce a form that can be absorbed in the mouth.

One in five adults are obese, but that could rise to one in three by 2010.

The hormone in question is called pancreatic polypeptide (PP), which the body produces after every meal to ensure eating does not run out of control.

We hit on the idea of a chewing gum because obese people like chewing

Professor Steve Bloom, lead researcher

There is evidence that some people have more of the hormone than others, and becoming overweight reduces the levels produced.

A vicious circle then results, causing appetite to increase, an inability to resist the temptation of food, and further increases in weight.

Early tests have shown moderate doses of the hormone, pancreatic polypeptide (PP), can reduce the amount of food eaten by healthy volunteers by 15% to 20%.

The team have now been given funding of £2.2m from the Wellcome Trust to take it forward.

As well as chewing gum, they believe it could be incorporated in a nasal spray.

Problem

Lead researcher Professor Steve Bloom said: "We have got a problem and we don't know what to do about it.

"We hit on the idea of a chewing gum because obese people like chewing."

Professor Bloom's team first noted the effect of the hormone in a group of patients with a particular pancreatic tumour that causes them to generate more PP.

Their bodies were kept permanently thin for long periods of time, yet they appeared to suffer no ill effects from the hormone.

Professor Bloom's team has not yet been able to study obese patients, but has tested the hormone out on a small group of 35 mildly overweight but otherwise healthy volunteers.

Participants were given injections of either PP or an inactive salt solution without knowing what they were receiving.

They were then offered a large buffet meal and invited to eat as much as they liked.

At the same time they were asked to answer questions about how hungry they felt.

Those given the treatment felt less hungry and ate between 15% and 25% less - than those who received the placebo.

A real treatment would aim at cutting food intake by 5% to 10% initially, and thereafter maintain control over appetite with a small reduction of about 1%.

Dr Ted Bianco, of the Wellcome Trust, said: "Over 30,000 deaths a year are caused by obesity in England alone, so there is a clear need to develop a treatment to tackle this problem.

"Yet this need for effective anti-obesity therapies is currently unmet. We believe that Professor Bloom's research holds great promise and, with our support, can be translated into tangible benefits to health."

Diabetes UK care adviser Libby Dowling said: "Although trials have shown that this drug can help reduce appetite, it has only been trialled on people who already have a relatively healthy weight.

"We would continue to recommend eating a healthy diet and doing regular physical activity as the first and best step to losing weight."