Labelling food and drinks with how much walking or running is needed to burn them off could help tackle the obesity crisis, researchers say.

While pre-packaged food must display certain nutritional information, such as calorie content, there is limited evidence that the approach changes what people buy or eat. 

Researchers involved in a new study have suggested converting calories into the amount of exercise needed to burn them off – for example, labels explaining that you would need to run for:

·       13 minutes after drinking a 330ml can of fizzy drink

·       22 minutes after eating a standard size chocolate bar

·       42 minutes after eating a shop-bought chicken and bacon sandwich 

The team say the approach puts calories in context and may help people to avoid overeating, or spur them to move about more in a bid to burn off the energy they have consumed. They also suggest it might encourage food producers to make products with less calories.

“We think there is a clear signal that it might be useful,” said Prof Amanda Daley of Loughborough University, first author of the research. “We are not saying get rid of current labelling, we’d say add this to it.”

Daley said a simple approach is important since it is thought we only spend about six seconds looking at food before deciding whether to buy it.

“In that [time] we’ve got to have something that you can easily understand and make sense of without having to have a PhD in mathematics to work out what [eating] a quarter of a pizza actually means,” she said.

“If I tell you something is going to take you 60 minutes of walking to burn, I think most people understand that and know that 60 minutes of walking is a long way.”

The study was carried out by researchers from Loughborough University, Birmingham Community Healthcare NHS Foundation Trust and the University of Birmingham. It was funded by Loughborough University and the National Institute of Health Research and published in the peer-reviewed BMJ Journal of Epidemiology & Community Health on an open-access basis, so it's free to read online here.

This study summarised the results of 14 previous trials of exercise labelling (called PACE, for physical activity calorie equivalent) compared to no labelling or other nutritional labelling. 

However, the research has limitations: most of the studies were based on hypothetical situations or laboratory-based work, and there was a limited number of them.

The studies also varied considerably in how they explored the impact of exercise-based labelling.

Overall, the summary found people selected less calories and ate less calories when their food choice included PACE labelling. However, the results varied a lot between studies and some of the methods used were unclear, meaning we have to be cautious about accepting the results.

Duncan Stephenson, deputy chief executive of the Royal Society for Public Health, welcomed the research, saying the charity’s own work showed such exercise-based labelling both made consumers think twice about their purchases, and motivated them to think about exercising.

But, he said, “real-life” studies are now needed to test the system’s impact in supermarkets and restaurants.