Jeremy Laurance: Is popping a pill really the solution to the obesity crisis?

One of the pleasures of being a health reporter is that certain stories guarantee you attention. When I put up last week's story about the diet pill that's twice as effective as any treatment currently on the market, certain members of the newsroom were soon beating a path to my desk, eager to learn more.

None of them was overweight, in need of a diet, or male. And that poses a dilemma. Even if the treatment is safe (pertinent in light of the suspension of Acomplia, an existing drug, last week), effective and affordable, is it an appropriate response to our national obsession with weight?

The pill is called tesofensine (it does not yet have a brand name), and it was discovered by accident when NeuroSearch, the small Danish biotech company that developed it was testing it as a treatment for Alzheimer's and Parkinson's diseases, and noticed that the patients were not getting better but were shedding weight. Professor Arne Astrup, a scientist from the department of human nutrition at the University of Copenhagen, was called in to investigate, and his trial, published in 'The Lancet', found patients who weighed 16 stone at the start of the study were up to two stone lighter at the end of it, 24 weeks later. "The pill that can help you drop two dress sizes in six months", the 'Daily Mail' helpfully explained.

When I called him, Professor Astrup was so enthusiastic about the drug that he said he'd bought shares in NeuroSearch – which, with stock markets in free fall, shows remarkable faith in his own judgement. But, as Hanne Leth Hillman, head of investor relations at Neuro-Search, told me, the market for obesity drugs is worth billions, and "you only need penetration of 0.5 per cent" to have a huge sales potential.

So there may be something here for both dieters and investors. But a word of caution. British researchers noted that the weight loss achieved in the study was similar to that claimed in the early trials of rival drugs, already on the market. And there was nothing particularly new about the mechanism of tesofensine. Longer experience has shown lower weight loss with the older drugs in later trials, and it was these pooled results that were compared with the first results for tesofensine. Like was not being compared with like, in other words.

But suppose Professor Astrup's instincts are right and it's a winner. We urgently need a solution to the obesity crisis. Is popping a pill the answer? Or does it seem like cheating?

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I was impressed by last week's Foresight study into mental health. I'm a sucker for those thumbnail reminders of how to increase one's contentment – be active, savour the moment, etc. But one trick they missed: the best aid to mental well-being is a job. Stress at work is a featherweight enemy compared with the giant of idleness.