Front of pack symbols showing how much exercise it would take to burn off calories could change consumer behaviour 2:05 More than two-thirds of people in the U.K. are either overweight or obese, and Shirley Cramer is hoping to curb that trend.

She's the chief executive of the Royal Society for Public Health in London and wants food labels to include information on how much exercise is needed to burn the calories the food contains.

It is called "activity-equivalent calorie labelling," and Cramer has written a commentary on the subject in the current edition of the British Medical Journal.

"Consumers take about six seconds to make up their mind about a product," she told CBC News.

Many people find nutritional labelling "too confusing" because labels are often loaded with all kinds of information that can be difficult to make sense of.

So, suggests Cramer, why not grab their attention with a catchy graphic illustrating just how much physical activity you'll need to do to burn off the calories you'll pack on by consuming the product.

The idea has its critics, however. Dr. Yoni Freedhoff of the Bariatric Medical Institute in Ottawa fears it could perpetuate the myth that exercise can lead to weight loss when, in fact, for most people, calories consumed outweigh the calories exercised away. 'This message oversimplifies exercise and undersells its benefits to everything else beyond weight.' (CBC)

For example, if you eat a blueberry muffin that has 265 calories, you'll have to walk it off for 48 minutes. If you're more of a runner, that'll take 13 minutes. But not everyone burns calories at the same rate, so consumers will have to adjust the information based on their individual situation.

The above estimates, says Cramer, apply to a 35-year-old male who weighs 77 kg.

"The idea that a pictorial which indicates what the equivalent activity would be if you ate those crisps, or the muffin, or have the soft drink [conveys] is immediate," says Cramer. "Everybody can understand that."

An 'in your face' strategy for fighting obesity

In a survey conducted by the Royal Society, almost two-thirds of about 2,000 respondents said they would support the introduction of activity-equivalent calorie labelling and over half said they would positively change their behaviour after viewing that kind of labelling.

Most people don't know how many calories the average person needs to maintain a healthy weight, says Cramer.

Many people find nutrition labels confusing and easy to ignore. (Kelly Crowe/CBC)

"We need to be creative ...in your face ... so this is a tactic, or a strategy, in the war on obesity," she said.

In a policy paper, the Royal Society for Public Health writes that targeting unhealthy food products with interventions that can positively influence behaviour change should be a priority for public health authorities.

Cramer says it's pointless to preach to people about good eating behaviour, but the new labelling she's proposing could help consumers make better, healthier food choices.

"If we put this activity-equivalent calorie labelling on unhealthier food, then we'd be hoping to make some difference in people's lives, that they would be making better choices," she said. "Anything to kick-start physical activity."

Exercise not a weight loss drug

Not everybody is sold on the idea. Dr. Yoni Freedhoff is the medical director of the Bariatric Medical Institute in Ottawa.

"People believe that exercise is the ticket to the weight loss express," he said.

But, in fact, exercise doesn't burn that many calories.

Calories consumed outweigh the calories exercised. For the most part, you cannot outrun your fork. - Yoni Freedhoff , Bariatric Medical Institute

"Having these food labels that say these are how many calories you need to exercise to burn this off, it perpetuates the notion that exercise and weight are tightly linked, and, surprisingly, they are not," Freedhoff said in an interview with CBC News.

Freedhoff said the majority of a person's weight is determined by their eating habits.

"This message oversimplifies exercise and undersells its benefits to everything else beyond weight and calories," he said. ​

Exercise is the world's best drug, says the obesity expert. It's just not a weight loss drug. Freedhoff says the activity-equivalent calorie labels speak to an overarching problem: people don't understand calories.

"I think we need to a better job of explaining to the public that calories consumed outweigh the calories exercised. For the most part, you cannot outrun your fork."