WeightWatchers is making major changes in its diet plan, adopting a new ‘ProPoints’ system because “science had moved on” and the previous style of calorie-counting had been proven to be inaccurate and “outdated”, The Grocer magazine reported.

The new plan, which will be announced on Monday, will be based on the amounts of carbohydrate, fibre, fat and protein in food. It will also factor in the energy used in chewing and digesting each particular food. Each dieter’s daily points will still be calculated, based on age, gender, height and weight.

In a nod to the real world, Weight Watchers followers will be granted ‘slush fund’ points, available for eating out, celebrations or a need to be just a little bit naughty.