A pill to shed pounds would be a miracle. Diets are no fun and exercise is hard work. Unfortunately, diet drugs have a chequered history, and the decision by the National Institute for Healthcare and Clinical Excellence to allow rimonabant - which its French manufacturers, Sanofi-Aventis, call Acomplia - to be prescribed on the NHS changes nothing.

Acomplia was lauded as a miracle drug after the early trials. It not only suppressed the appetite, but it helped people to stop smoking. Unfortunately, further trials have shown it increased the risk of depression, anxiety and suicidal thoughts. The US won't licence it but 11,000 British people are already taking the drug.

The guidelines state that, before you get Acomplia, you have to be considered for one of the other modern NHS diet pills, Xenical and Reductil. The former works by preventing the absorption of excess fat, so that it just passes straight through you. Delightful. The latter, an appetite suppressant, can increase your blood pressure. None of the drugs will be prescribed unless you are seriously dieting and trying to change your lifestyle.

The hunt for a weight-loss magic bullet has been littered with disaster. Thirty years ago, amphetamines were all the rage because they suppressed the appetite. However, dieters became addicted to them. In 1997, the Food and Drug Administration (FDA), which regulates medicines in the US, ordered the withdrawal of fenfluramine, one of the components of the diet pill Fen-phen, and of dexfenfluramine, known as Redux, because they caused heart-valve disease. The same year, the FDA warned about Metabolife 356, a herbal diet aid. It contained a natural stimulant, ephedra, and was linked to more heart deaths. It was withdrawn in 2004.

It makes diet and exercise look quite attractive after all.