Sophisticated diets 'no advantage'

A healthy, balanced diet is the best way to lose weight

Sophisticated diets based on eating food from the major nutrient groups separately are no more effective than simple approaches, say researchers.

"Food-combining" diets work on the principle that it is healthier and more effective to eat carbohydrates, fats and proteins separately.

The theory is that the body finds it more easy to digest food in this way.

The diets first came to prominence with the Hay Diet in the 1930s, and have gained popularity in recent years.

As well as helping people lose weight, supporters claim the diets can reduce the risk of ulcers, allergies, and gain energy.

The Hay System is credited with alleviating the symptoms of chronic diseases such as arthritis and diabetes.

Dr Alain Golay and colleagues from the University of Geneva carried out a carefully controlled, six-week in-patient trial comparing the effects of two energy-restricted diets on weight loss.

Low-calorie diet

Fifty-four obese patients were all fed a low-calorie diet (1100 kcal/day) designed to provide approximately 45% of energy as carbohydrate and 30% as fat.

Half the subjects ate the diet normally and half as a food-combining diet, eating fat and carbohydrate at different times.

It is quite difficult to follow that type of diet over a long period of time because you are cutting out certain kinds of food groups at each meal and that is so boring

Dr Wynnie Chan, British Nutrition Foundation

The subjects on the food-combining diets tended to eat a slightly lower fat diet (25% fat) than those on the normal, balanced diet (31% fat).

The researchers thought that this alone might help to produce better weight loss in the people who ate the food-combining diet.

However, the people who ate a normal, balance diet lost 7.5kg compared to a loss of just 6.2kg for those on the food-combing diet.

Both groups showed identical decreases in body fat and plasma glucose, cholesterol, triglycerides and insulin levels.

This indicates that the known health benefits associated with weight loss were the same for both diets, irrespective of the pattern of fat and carbohydrate intake.

Dr Wynnie Chan, a nutrition scientist at the British Nutrition Foundation, said the benefits of food-combining diets were not scientifically proven.

She said: "It is quite difficult to follow that type of diet over a long period of time because you are cutting out certain kinds of food groups at each meal and that is so boring."

Dr Chan said the best way to control weight was to take regular exercise, to eat lots of fresh fruit and vegetables and as many low-fat products as possible.

The research is published in the International Journal of Obesity.