Following a strict diet for just two days a week, instead of constantly calorie counting, is a far more effective way of losing weight, research has revealed.

The study at the University Hospital in South Manchester found that women who cut carbohydrates for two days a week while being allowed to eat as much as they liked on other days lost almost twice as much weight as those on a full-time diet.

The researchers put 115 women volunteers on one of three diets.

The first diet involved consuming just 650 calories a day for two days of the week, including cutting carbohydrates such as pasta, bread and potatoes and all fatty foods.

For the other five days they were encouraged to stick to healthy foods but could eat as much as they liked.

Women on the second diet were also banned from carbohydrates for two days of the week but were not given a calorie restriction. They could also eat as much as they liked for the rest of the week.

The third group followed a conventional weight-loss diet, which involved sticking to about 1,500 calories every day and avoiding high-fat foods and alcohol.

After three months it was found that the women on the two-day diets had lost an average of nine pounds (4kg), nearly twice as much as those on the full-time diet, who lost just five pounds (2.4kg).

Dr Michelle Harvie, of the Genesis Breast Cancer Prevention Centre at the hospital, said there seemed to be a “carry over effect” on the two-day diet meaning the benefits continued on the days when the women ate normally.

Harvie, who presented her findings at the Breast Cancer Symposium conference in San Antonia, Texas added: "What we found was that they naturally ate less."

Pamela Goldberg, chief executive of the Breast Cancer Campaign said: "There are many breast cancer risk factors that can't be controlled, such as age, gender and family history - but staying at a healthy weight is one positive step that can be taken.

"This intermittent dieting approach provides an alternative to conventional dieting which could help with weight loss, but also potentially reduce the risk of developing breast cancer."

The two-day diet the women followed:

Breakfast: Fruit tea and a banana, or mug of milky coffee.

Mid-morning: Can of diet cola, or cup of tea and plum.

Lunch: Carrot and coriander soup and half-pint of milk, or salad, glass of squash and half-pint of milk.

Mid-afternoon: Glass of squash, or glass of sparkling water and Satsuma.

Dinner: Soy sauce and ginger stir-fry with two vegetables and glass of water, or vegetable curry with two vegetables, half-pint of milk and cup of tea.

Supper: Pint of milk, or hot milk with cinnamon and sweeteners.