Is labelling food with calorie burn times to beat obesity a good idea?

LONDON -- Food should be labelled with the amount of exercise needed to burn off its calories, the Royal Society for Public Health in Britain is arguing.

Writing in the British Medical Journal, RSPH chief executive Shirley Cramer called for the introduction of "activity equivalent" calorie labelling, with symbols showing how many minutes of certain types of exercise are required to burn the product's calories. 

"The aim is to prompt people to be more mindful of the energy they consume and how these calories relate to activities in their everyday lives, to encourage them to be more physically active," wrote Cramer in the BMJ.

According to Cramer, front-of-pack information needs to be "as simple as possible". 

"For example, the calories in a can of fizzy drink take a person of average age and weight about 26 minutes to walk off."

"Given its simplicity, activity equivalent calorie labelling offers a recognisable reference, accessible to everyone," says Cramer. 

This comes after research by Imperial College London -- published in the Lancet last week -- revealed that the number of adults classified as obese now outweighs the number of underweight adults in the world.

But, while the RSPH's aim to make information about calorie expenditure easier to understand is laudable, not all nutrition experts are on board with making generalisations about the time it takes to burn calories. 

"It is eating behaviour that needs to change not labelling."

"It seems a daft idea as a significant proportion of caloric intake is used to support basal metabolism i.e. breathing snd staying alive, which is typically between 1200-1500 kcal/d," Thomas Sanders -- former Head of Nutritional Sciences Division at Kings College London -- told Mashable. 

Sanders also has concerns that the front-of-pack advice would exacerbate eating disorders.

"I think the downside of the advice is that those who are most of risk of eating disorders would latch onto it, rather than than the obese or overweight," Sanders continued.

Dr Jemima Stockton -- Research Associate at UCL's Epidemiology and Public Health Department -- told Mashable that a one-size-fits-all approach to calories doesn't work. 

"For example, a heavier person will burn the same number of calories in a weight-bearing physical activity like jogging in less time than a lighter person because they will be carrying more weight," says Stockton. 

A person-specific activity equivalent labelling system would be ideal, says Stockton.

"Ideally, I suppose there’d be some kind of biometric system where your pork pie, or whatever, detected your age and weight as soon as you picked it up, and then spoke to you to tell you how long you’d need to walk for to balance your energy needs," Stockton continued. 

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