Britain needs to go on a diet, Public Health England has warned, as it set out new calorie guidelines to cut meal sizes, ruling out favourites like Fish and Chips or a Sunday Roast.

Under its new ‘One You’ campaign, launched today, Britons are being encouraged to stick to 400 calories at breakfast, and 600 calories for both lunch and dinner.

Critics branded the daily allowance too low for growing children and close to war rations, but public health experts warned that obesity had now become ‘the norm’ and said most people were eating hundreds of extra calories each day.

The new restrictions would rule out traditional meals such as Fish and Chips and a Sunday Roast which are both around 800 calories, as well as many curry, pizza and pasta dishes.

"Britain needs to go on a diet,” said Duncan Selbie, chief executive at PHE. "The simple truth is on average we need to eat less. Children and adults routinely eat too many calories and it's why so many are overweight or obese.”