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 all packaged food must display certain nutritional information, such as calorie content, there is limited evidence that the approach changes what people buy or eat. Meanwhile, waistlines continue to expand.
A new study backs another approach to labelling: displaying small symbols showing how much physical activity is needed to compensate for consuming the item.
A fizzy drink containing 138 calories, for example, could be accompanied by a small symbol of a person showing it would take 26 minutes of walking or 13 minutes of running to burn off.
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.”
Writing in the Journal of Epidemiology & Community Health, Daley and her colleagues report how they analysed data from 14 previously conducted studies exploring the impact of an exercise-based labelling system.
The team found that compared with no labelling or other labelling approaches taken together, participants selected on average about 65 fewer calories per meal when exercise-based labels were present on food or menus. That’s less than a single chocolate digestive biscuit at 83 calories.
Digging deeper, the team found people selected 103 fewer calories when the exercise-based labels were used compared with no labelling alone.
“In restaurants and coffee shops, where we eat most of our high-calorie foods, you would typically see no labelling at all,” said Daley.
However, there was no clear benefit compared with other types of labelling such as calorie-only labelling, daily intake labelling or “traffic light” labelling.
Similarly, an analysis based on studies that looked at calories actually consumed revealed individuals ate about 110 calories fewer when food was labelled with exercise-based information compared with no labelling.
While the gains may sound small, Daley said such reductions add up across meals.
“People think that obesity is caused by gluttony. It isn’t. Obesity is caused by all of us eating just a little bit too much,” she said.
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.
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.
Dr Stacey Lockyer of the British Nutrition Foundation also said an approach which reduces people’s daily intake by up to 195 calories is worth considering. She said that, on average, adults overshoot their daily recommended calories by this amount, while overweight and obese adults consume approximately 320 excess calories per day.
Lockyer noted that there is evidence an exercise-based labelling system appeals to consumers.
Dr Frankie Phillips, a registered dietitian and spokesperson for the British Dietetic Association, said exercise-based labelling could also prove confusing, while a focus on calories – although a useful indicator – does not tell a consumer whether food or drink is “healthy”.
“For example, calories labelled on a sandwich might come to around 400kcal whereas a chocolate confectionery bar might be 350kcal,” she said. “If calories are given central importance then the chocolate bar would appear to be a better choice, whereas a more balanced approach would obviously show that a sandwich is far superior nutritionally, despite being higher in calories.”