Alcohol is second only to fat in terms of its calorie content and makes up 10 per cent of the average adult's diet, according to new research.
The World Cancer Research Fund says alcohol is almost as energy-dense as fat and that few people count their 'liquid calories' when adding up how much they eat in a day.
Fat has nine calories per gram, while alcohol has seven, the organisation adds.
One pint of lager is roughly the same as a Mars bar, while a 250ml glass of white wine has around 200 calories - more than two chocolate digestive biscuits or a packet of crisps.
Kate Mendoza, head of health information at WCRF, said: "The calories in alcoholic drinks account for a significant proportion of a drinker's calorie consumption while providing little, if any, nutritional benefit.
"Cutting down on drinking can have a big effect on weight loss or maintaining a healthy weight.
"Recent reports have shown that people are unaware of calories in drinks and don't include them when calculating their daily consumption.
"This is important from a cancer perspective because, after smoking, being overweight or obese is the biggest risk factor."
Dry January challenge
On average, men need around 2,500 calories per day, while women need 2,000. Mendoza said: "Cutting down on drinking can have a big effect on weight loss or maintaining a healthy weight.
"There is also strong scientific evidence that alcohol itself is a cancer risk factor, possibly through damaging our DNA, in cancers of the breast, bowel, mouth, oesophagus and liver."
In order to combat alcohol consumption in the UK, Alcohol Concern has launched Dry January. It is challenging people to not drink any alcohol for 31 days and over 3,500 people have already signed up.
Cancer Research UK is also encouraging people to take part in the challenge after research found 39 per cent of people had given up their New Year's resolutions within two weeks of making them.
Ed Aspel, who is leading the charity's Dryathon campaign, said: "We wanted to find out how good the great British public are at sticking to those fabled New Year's resolutions, which it turns out we find harder to stick to than we might think.
"We'd encourage the fifth of us who already plan to cut down on alcohol to go one step further and give Dryathon a go - by raising some much needed cash to help beat cancer, you'll have an even better reason to make it past the two week mark and stick to the resolution for the whole of January."