Dieting company WeightWatchers’ fat and calorie-based points is set to be replaced by a new system that allows treats, from birthday meals out to the odd fast food binge.

According to Grocer magazine, the international dieting giant said it was adopting the ‘ProPoints’ system because ‘science had moved on’ and the previous style of calorie-counting had been proven to be inaccurate and ‘outdated’, reports the Daily Mail.

The new plan will centre on the amounts and types of protein, carbohydrate, fibre and fat in food, rather than its fat and calorie content.

A typical member will be given a typical daily allowance of up to 29 of the recalculated ProPoints, compared with 18 old-style points.

But the big selling point is a slush fund of 49 ‘real living’ points, which can be dipped into when on a girlie night out or when only fast food will do.

A gin and low-calorie tonic will account for two ProPoints, a pint of lager adds six and a Big Mac costs 12 points.

Although treats were allowed under the old system, they had to come out of the daily allowance of points.

In a further change all fruit and most vegetables will be point-free, allowing slimmers to fill up on healthy foods.

Under the old system, a banana and a low fat chocolate bar carried the same number of points, meaning there was little incentive to choose fruit over a sweet treat.