Video report by ITV News Reporter Stacey Foster
Telling people how much exercise they need to do to burn off food and drink could be more effective at encouraging healthier choices than simply listing the calories, a study has claimed.
The Royal Society for Public Health has called for Physical activity calorie equivalent or expenditure (Pace) labelling to be introduced instead of the current system.
Consumers could find out how many minutes or miles of exercise they need to do to burn off the calories in a particular product.
But how much exercise do you need to do to work off your favourite foods?
The average man needs around 2,500kcal a day to maintain a healthy body weight, while the average woman needs around 2,000kcal a day.
The total number can vary depending on a person's age, weight and activity level.
According to a Harvard Medical School study, 30 minutes of these popular sports can burn up to almost 500 calories:
Walking (4.5 mph): 150 - 222
Running (7.5 mph): 375 - 555
Rowing: 255 - 377
Swimming: 180 - 266
Football: 210 - 311
Cycling (15 mph): 300 - 444
Weight Lifting: 90 - 133
And according to the US institution, even sleeping and watching TV can burn up to 30kcal when done for half an hour.
But how much of these activities would you have to do to burn off your favourite foods?
An average slice of takeaway Margherita pizza - which comes in at around 108kcal - could be burned off in a 30-minute walk.
But you would have to increase your pace to a run to burn off a 508kcal MacDonald's Big Mac burger.
And if you wanted a can of Coca-Cola with your burger - which is around 139kcal - you would have to add on a short weight lifting session after your meal.
British favourite Cadbury Dairy Milk is an even harder treat to burn off.
Although a small bar is only 240kcal, a 200g full-size bar can be up to 1,000kcal, meaning you could still be on the football pitch after the game has finished.
Another food that's easy to overindulge on is the second helpings of turkey on offer over the festive period.
Just two small portions of roast turkey - at 266kcal total - could lead to a heavy session in the gym for some intense rowing.
Surprisingly, filling your plate with turkey is also around the same number of calories as just one Asda 'Chosen by You' mince pie.
At 274kcal per pie, it might be a good idea to leave the rest of the packet to Santa Clause.
Researchers from Loughborough University predict the new system could shave off up to around 200 calories per person each day on average if widely applied.
This could help prevent population-level obesity, as regular over-consumption of small amounts of calories is a key contributing factor, they said.
They believe the current system is having a limited effect on changing purchasing and eating behaviours as many people do not understand the meaning of calories or fat levels in terms of energy balance.
Data gathered from 14 randomised controlled trials compared the impact of Pace labelling with other types on the selection, purchase and consumption of food and drinks, excluding alcohol.
They found that fewer grams of food and beverages were consumed, fewer calories selected and fewer calories consumed when Pace labelling was used, compared with other types of label or no labels.
Some 65 fewer calories per meal were selected when Pace labelling was used, and 80-100 fewer calories consumed.
However, they cautioned that many of the studies were not carried out in real-life environments, such as restaurants and supermarkets.
The authors said the effects of Pace labelling could vary according to context, with marketing, time constraints and price all likely to affect choices.
In the report, they wrote: “Pace labelling is a simple strategy that could be easily included on food/beverage packaging by manufacturers, on shelving price labels in supermarkets, and/or in menus in restaurants/fast-food outlets.
“Public health agencies may want to consider the possibility of including policies to promote (it) as a strategy that contributes to the prevention and treatment of obesity and related diseases.”
Duncan Stephenson, deputy chief executive of the Royal Society for Public Health, said: “We welcome this new research which builds the case for introducing activity equivalent food labelling.
“Our own research showed that using this type of labelling did make people think twice about the calories they were consuming, and when compared with other forms of labelling, people were over three times more likely to indicate that they would undertake physical activity.
“This type of labelling really does put an individual’s calorie consumption in the context of energy expenditure, and knowing how out of kilter we sometimes are, this partly explains the record levels of obesity we face.
“We would like to see further research to test if the effect on calorie consumption is sustained when Pace labelling is applied in other settings such as restaurants and supermarkets.
“Although the difference Pace labelling makes may seem small, these small changes can make a big overall difference to calorie consumption, and ultimately weight gain.”
The paper is published in the Journal of Epidemiology & Community Health.