After poring over 20 research studies, one of the world’s leading experts has come back with his answer: the low-GI (glycaemic index) diet.

David Ludwig from the Children’s Hospital, in Boston, USA, says that every doctor should advise his patients to adopt the GI diet, especially as a lifestyle choice to prevent diabetes, heart disease and obesity.

It’s key is in differentiating between ‘good’ and ‘bad’ carbohydrate. Instead of banning all carbohydrate (as do the Atkins and other high-fat diets), it instead rules out those carbohydrates that rapidly increase blood glucose levels. This includes most processed foods, such as breakfast cereals, white bread and white rice, cakes and biscuits, and more surprisingly, perhaps, potatoes (especially fried), and drinks such as beer.

Low-GI foods include fruits, vegetables, pulses and grains that have not been overly processed, such as brown rice. Meat is allowed, of course, but Michel Montignac, one of the pioneers of the low-GI diet, recommends that it shouldn’t form more than a third of the diet.