The 'full up' hormone that could help cut obesity

(Filed: 04/09/2003)

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British scientists yesterday unveiled what they claim is the most promising anti-obesity drug so far: a hunger-regulating hormone that fat people lack.

The research could mark a major advance in efforts to combat the western world's growing levels of obesity, which at current rates will overtake smoking as the leading cause of death.

Prof Steve Bloom, the head of the London-based team, has studied PYY3-36, a small protein about the size of insulin, since 1984. It is released with every meal and acts on mechanisms in the brain that regulate appetite.

Writing in the New England Journal of Medicine, Prof Bloom and his colleagues reported "extremely promising" studies of 24 volunteers. These showed that obese people have, on average, only two thirds the levels of PYY3-36, made in their intestines, compared with lean people.

The team found that injecting the hormone into volunteers cut their appetite. Consuming fat produces a bigger rise in the hormone, as do certain types of fibrous food, suggesting that a high fibre diet may offer an alternative way to stimulate the hormone.

What most excited the team at Imperial College London was that hormone infusions could also cut by about a third the calories both lean and overweight people ate. Side effects were negligible. The volunteers could not tell when they had had an active infusion or a saline placebo.

Prof Bloom said: "These findings suggest that boosting PYY3-36 offers a novel approach towards treating the epidemic of obesity in our society."

But he said he was unlikely to find funding for further trials of the hormone, which is responsible in part for making us "feel full".

Because the hormone occurs naturally, the discovery cannot be patented and drugs companies are reluctant to invest in the research.

"You cannot bring things to market if they are not patentable," Prof Bloom said.

The traditional way to sidestep this would be to make a chemical derivative that can be patented. Talks with Pfizer have started.

But to create and test a derivative would delay its use by up to a decade when, as Prof Bloom points out, "about 1,300 people a week are dying from obesity complications in Britain".

By comparison, PYY3-36 "works straight out of the box and does not need any development", he said.

Further tests on the hormone would take only two or three years and offer hope to the 17 per cent of children who were obese.

"Our population would live for another 10 to 15 years if we were able to control our appetites," Prof Bloom said.

"I have been trying for 30 years to persuade people to lose weight. All the long-term follow-up studies show almost 100 per cent failure. We hope to prove that we can help people with these injections."

Dr Rachel Batterham, the co-author of the study, who is now based at University College London, warned people not to expect miracles.

"If this passes clinical trials, it will not be a wonder treatment. PYY3-36 would be useful only if used in addition to changes in eating habits and any NHS treatment would probably be restricted to those most at risk of associated disease, such as type 2 diabetes."

Another issue is the high cost of the hormone. At current prices, a daily injection of PYY3-36 would cost about £20, compared with £2 for a shot of insulin. Being in the form of injections, it would also be less acceptable to some people than a pill.

Eleanor Kennedy, the research director at Diabetes UK, said: "Although this study is small, the results are very interesting. Anything which helps obese people regulate their appetite could potentially reduce the number of people developing type 2 diabetes. There needs to be further research and we shall be following it with great interest."

Dr Ian Campbell, the chairman of the National Obesity Forum, said: "If this does lead to the development of even better drugs, it must be welcomed. But I am conscious that we have been here before and that other wonder molecules have failed."

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