A study of five men and nine women conducted by scientists at the Karolinska Institute in Huddinge, Sweden, found that eating like a caveman may trim the waist and protect against heart disease.

Volunteers were put on a stone-age diet of berries, nuts, lean meat, fish and vegetables while cutting out cereals, dairy products and refined sugar.

After just three weeks they had lost five pounds in weight, their waistlines were slimmer, and their blood pressure was lower.

Those taking part in the Swedish study had to stick to a food list which included lean meat, unsalted fish, fresh or frozen fruit, berries, vegetables — but not beans — most kinds of nuts, canned tomatoes, lemon or lime juice, spices, and coffee or tea without milk or sugar.

Dairy products, beans, peanuts, salt, pasta, rice, sausages, sugar, fruit juices and alcohol were all banned.