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Alcohol should have a calorie content label in order to reduce obesity, according to public health doctors.

The doctors warn a large glass of wine can contain around 200 calories - the same as a doughnut.

Yet the Royal Society for Public Health says the vast majority of people are blissfully unaware.

Public Health Minister Jane Ellison said "great strides" had been made with labelling food, and that the government will look at the issue.

The drinks industry said it was open to the idea of calorie labels, but that labelling drinks with units of alcohol was more important.

The UK is one of the most obese nations in the world with about a quarter of adults classed as obese.

'Startling'

Food already comes with calorie information, but alcohol is exempt from EU food labelling laws.

And the European Commission is considering whether drinks should also carry such information.

Research by the Royal Society for Public Health suggested the measure would be popular with British drinkers.

The RSPH's chief executive, Shirley Cramer, told the BBC: "Quite startling really - 80% of adults have no idea what the calorie count is in anything they're drinking and if they do think they have an idea they totally underestimate it anyway.

"It could help the nation's waistlines as well as probably reduce alcohol consumption."

In a small pub experiment conducted by the society, people who were told the calories content of their drink consumed 400 fewer calories in a session.

How many calories

A large 250ml glass of 8% wine is 170 calories

The same amount of 14% wine is 230 calories

A 275ml alcopop can be 170 calories

A pint of 4% beer is more than 180 calories

Four pints on a night out equates of two-and-a-half burgers or 73 minutes of running

In comparison a sugary doughnut comes in around 200 calories

Source: Royal Society for Public Health, Drinkaware

Estimates suggest 10% of an adult's calorie intake comes from alcohol.

Gram for gram it is the second most calorie-dense source of energy, just behind fat.

'Open to discussion'

The Portman Group, which represents drinks manufacturers, said it took the health consequences of drinking "very seriously" and provided calorie information on the Drinkaware website.

In a statement it said: "Drinks producers can play a key role in informing and educating consumers and are open to further discussions about calorie information.

"However, it is essential that alcohol content, not calorie content, should primarily inform consumer decision-making."

Media playback is unsupported on your device Media caption Brendan O'Donnell says cutting down on alcohol helped him lose more than 11 stone

Tam Fry, from the National Obesity Forum, said the government had been dragging its feet on the issue.

"A calorie-count on wine and beer bottles can't come soon enough.

"Just one premium lager contains by itself contains enough calories for a small meal and, added to the meal itself, eats up a chunk of anyone's maximum allowance."

Ms Ellison said: "It is very positive to see that people want more information to help them lead a healthier life.

"We have made great strides in food labelling and customers can see at a glance the calories they are consuming on many products.

"While it is already possible for alcohol producers and retailers to display calorie content on their labels, we will continue to look at what else can be done to help people make healthier lifestyle choices."

Jackie Ballard, the chief executive of Alcohol Concern, said: "Much more needs to be done to raise awareness of both the contents and the harms which can be caused by alcohol.

"You walk into any shop and the calorie, fat content, sugar and more are on the back of food packets and we don't see why alcohol should be any different."