Leading article: How to shed the pounds – and keep them off

The global obesity epidemic is one of the biggest health challenges of our time. We know how to take the weight off – eat less, exercise more – and millions struggle repeatedly to do so. What we don't know is how to keep it off. This is not only a matter of psychology. Losing weight triggers a physiological response, as the body tries to protect itself against slow starvation.

In overcoming the body's defences against losing weight, the glycaemic index (GI) of carbohydrates consumed may be key. The GI describes the speed with which the food is digested and the boost to the blood glucose level. The lower the GI, the slower the digestion and the longer satiety lasts.

Today, the world's largest diet study, called Diogenes (Diet, Obesity, Genes) by the noted obesity researcher, Professor Arne Astrup of the University of Copenhagen, shows that a high protein/low GI diet is most effective at maintaining weight loss. The credibility of the finding is strengthened by Professor Astrup's own scepticism that selecting low GI foods would have any impact. When he saw the results, he had to change his mind.

If the finding is confirmed, official European nutrition recommendations will have to be rewritten. The high protein/low GI diet could become the gold standard for obesity control.