Calorie labelling of food on menus and products leads people to choose slightly fewer calories finds a new Cochrane review co-led by UCL researchers.
For the study, published in the Cochrane Database of Systematic Reviews, the team examined evidence from 25 studies on the impact of calorie labelling on food selection and consumption.
They found that calorie labels in supermarkets, restaurants and other food outlets led to a small reduction in the calories people selected and purchased. The average reduction was 1.8%, which would equate to 11 calories in a 600 calorie meal - or around two almonds.
Small daily changes in energy consumption can have meaningful effects if sustained long-term, and most adults tend to gain weight as they age. A UK government report estimated that 90% of 20-40 year olds in England will gain up to 9kg over 10 years, and that reducing daily energy intake by 24 calories per day - roughly 1% of the recommended intake for adults - would prevent this increase.
Senior author, Dr Gareth Hollands (IOE, UCL's Faculty of Education & Society and University of Cambridge) said: "Our review suggests that calorie labelling leads to a modest reduction in the calories people purchase and consume.
"This may have some impact on health at the population level, but calorie labelling is certainly no silver bullet. Our previous version of this review from 2018 reported a potentially larger effect but was inconclusive because there was significant uncertainty over the results. This update has reduced that uncertainty, and we can now say with confidence that there is very likely a real, albeit modest, effect."
The new update compiled by researchers at UCL, Bath Spa University, the University of Cambridge and the University of Oxford, used evidence from 25 studies with a strong emphasis on real-world field settings, with 16 of the studies being conducted in restaurants, cafeterias, and supermarkets.
The studies that were analysed encompassed over 10,000 participants from high-income countries including Canada, France, the United Kingdom and the USA. Only two of the studies included alcoholic drinks, and their results were too uncertain to draw any meaningful conclusions.
Lead author, Dr Natasha Clarke (Bath Spa University), said: "This review strengthens the evidence that calorie labelling can lead to small but consistent reductions in calorie selection.
"While the overall impact on individual meals or food purchases may be modest, the evidence is robust.
"The cumulative effect at a population level could make a meaningful contribution to public health, especially as calorie labelling becomes more widespread."
While calorie labelling shows promise, concerns remain about its possible impact on people at risk of disordered eating. The review noted a lack of data in the included studies on possible harms, including mental health impacts, and the authors recommend future research to assess this.
Dr Hollands said: "Calorie labelling to reduce the calories that people consume remains somewhat contentious, both in terms of whether it has any effect, and whether potential benefits outweigh potential risks or harms.
"We can now say with considerable confidence that it does have a small but potentially meaningful effect on people's food choices. Labelling may therefore have a useful role, ideally alongside a broader set of approaches that place more onus on industry rather than individuals, such as taxes, marketing restrictions and reformulation. However, we should not expect miracles, and any implementation of calorie labelling must balance the many potential positive and negative impacts of such policies."
