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A study published in Nature Human Behaviour looks at the association between calorie labelling and calories purchased or consumed.
Dr Hilda Mulrooney, Reader in Nutrition & Health, London Metropolitan University, said:
“The press release is an accurate reflection of the findings of the paper. In my view the study should not be taken as evidence that this policy has no efficacy. It highlights that by itself, calorie labelling will not be sufficient to address problems driven by a very complex food system. Some groups (e.g. young, male and white ethnicity) buy and/or consume more from the out-of-home food sector (OHFS). Some of these groups (e.g. younger, white ethnicity but also higher education level) also underestimated calorie content less after compared with before policy implementation, although because of the study type we can’t say this relationship is causal, and the effect was not large. The authors identified the timing of the study as potentially influencing the results (just after Covid restrictions were lifted), but it is also the case that the context was not captured (e.g. eating out to celebrate could result in noticing/using calorie information less). It is also possible that consumers may use the calorie information on dishes previously and after that relied on their previous knowledge to guide their current behaviours.
“The authors suggest that calorie labelling is not just potentially useful for influencing consumer behaviour but also food reformulation. It is unclear from this study whether and to what extent any such reformulation may have taken place although it was not evident for continuously available menu items. Reformulation could result in marked changes to the overall calorie and nutrient content of dishes, thereby affecting consumer intake even without a change in their conscious behaviours. Given that most of our food-related decisions every day are unconscious, this is an important route to improving dietary intakes. In this study, the calorie content of out-of-home food sector meals purchased and consumed was well above the UK public health recommendation of 600kcals/meal. This again suggests that reformulation, including portion sizes, is an aspect that needs attention and could make a real difference particularly to those groups who purchase and consume out-of-home food sector foods regularly.
“It was also noteworthy that despite the policy being mandatory, an estimated 20% of English businesses were shown in other research to be non-compliant – pointing to the need for monitoring and enforcing business engagement.
“There was marked underestimation of the calorie content of foods purchased, although this was lower post compared with pre-implementation. This highlights the need for ongoing education and calorie labelling is part of this. Consumers cannot make informed choices without information. Linked to this, the format and presentation of nutritional information needs to be clear, legible and understandable to consumers. Understanding what works best for consumers needs exploration.”
Prof Sarah Berry, Professor of Nutritional Sciences, King’s College London, said:
Does the press release accurately reflect the science?
“The press release accurately reflects the science reported in the manuscript.
Is this good quality research? Are the conclusions backed up by solid data?
“This type of research is challenging as dietary assessment and energy estimation of foods are subject to considerable error. However, the researchers attempted to control for this error as much as is possible.
Have the authors accounted for confounders? Are there important limitations to be aware of?
“The key limitations of any research involving dietary assessment and measurement of energy values of foods are the inherent errors in these measurements. However the authors acknowledge these in the manuscript.
“This study highlights the limited effectiveness of mandatory labelling in reducing calorie intake, though it does increase awareness of food choices. The fact that participants were more likely to notice calorie labels when ordering from pubs, possibly due to spending more time reviewing the menu, furthers the idea that by encouraging more mindful eating we can improve dietary quality. An assessment of diet quality as well as calories would have been an interesting element to this research for the future.
“However, the overall impact on behaviour change is modest, highlighting the need for stronger interventions to address the broader factors which contribute to our unhealthy food environment. Whilst an important step in assessing government interventions to tackle obesity, the research is limited by reliance on self-reported data and potentially inaccurate calorie information from businesses.”
Prof Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:
“This a high-quality study with a very large sample size that explores the possible impact of mandatory calorie labelling on food purchased outside the home in the UK. Mandatory labelling was associated with a doubled awareness of calorie labelling (to around 32% of purchasers from 16% before implementation). However, the difference was greatest among those who were better off as opposed to the poorest. It also seemed that labelling was more likely to be noticed in pubs rather than cafes which the authors attribute to time spent perusing the menu. However, the implementation of mandatory labelling had no statistically significant association with self-reported calorie intake. Calories consumed in fast food outlets were greater compared with cafes, but far more calories were consumed in pubs and restaurants.
“The major weakness is in the design because the estimates were made in the control and intervention periods at different time points. Consequently, it is possible that there could be time related changes in behaviour that affect food choice that are unrelated to labelling (e.g. increased cost of food and less disposable income).
“The takeaway finding from this study is that on its own mandatory calorie labelling is an ineffective public health measure to prevent obesity. This would support the view that calorie labelling alone does not motivate people to change their dietary habits. However, calorie labelling is useful for individuals who are motivated. Mandatory nutrition labelling has also helped computer programmes and apps provide accurate and up to date estimates of nutrient intakes using product bar codes which is useful for nutritionists, dietitians and motivated individuals. Consequently, it would be a backwards to step to abolish mandatory calorie labelling for the out of the home food sector.”
Prof Keith Frayn, Emeritus Professor of Human Metabolism, University of Oxford, said:
“Mandatory calorie labelling of menu items in larger outlets in the out-of-home food sector is one of a number of measures introduced in recent years in an attempt to reduce the incidence of overweight and obesity. It should not be seen as an end in itself, more as part of a package of measures. The measurements reported here were made before, and around 6 months (4 to 8 months) after, the introduction of mandatory calorie labelling, so this is an early snapshot. Although the researchers found no significant decrease in calories purchased or consumed, the range of responses was wide and subject to all the well-known difficulties of recording what people eat. Despite those difficulties, there was a significant increase in people noticing the calorie labelling and claiming to be influenced by it. These must be good signs of increasing awareness. It would be useful to see the study repeated a longer time after the introduction of labelling. One response noted elsewhere is that outlets may reduce the calorie content of meals offered; it seems probable that this will take time. In short, this early snapshot should be seen as encouraging rather than disappointing.”
Prof Amanda Daley, Professor of Behavioural Medicine; NIHR Research Professor in Public Health; and Director of the Centre for Lifestyle Medicine and Behaviour, Loughborough University, said:
“One problem with calorie labelling is that it just provides numbers on a page, without any context for the public to understand what the numbers actually mean when they are making decisions about food.
“The study was based on self-reported data rather than actual transactions or the food consumed so this is important to consider when interpreting the results.
“If we really want to accurately examine the impact of mandatory calorie labelling, we need to conduct studies that compare actual food transactions in eating establishments before and after the policy was introduced, rather than using self-reported data.”
Toby Lasserson, Deputy Editor in Chief & Head of Methods & Evidence Synthesis Development, The Cochrane Library, said:
“This carefully conducted survey can tell us something about how people perceive their own purchasing behaviour, but we should be careful not to place too much value on what it tells about the impact of this policy on calories purchased. The researchers themselves clearly acknowledge that a before and after survey does not permit the attribution of cause. In this case other measures were also introduced over time that could have influenced purchasing behaviour or changed the type of food that was prepared and sold across the different outlets. Randomised studies will be able to control for some of the confounders acknowledged in the paper with a contemporary control group. Such designs will provide more reliable evidence on the effect of menu labelling on calories purchased.”
‘Evaluating the association between the introduction of mandatory calorie labelling and energy consumed using observational data from the out-of-home food sector in England’ by Megan Polden et al. was published in Nature Human Behaviour at 16:00 UK time on Monday 25 November 2024.
DOI: 10.1038/s41562-024-02032-1
Declared interests
Dr Hilda Mulrooney: “I am a committee member of the British Dietetic Association Obesity Group; a committee member of the European Specialist Dietitians Network (Obesity) and a member of the Obesity Management Collaborative. I am Council Member for Public Health of the Nutrition Society. All of these positions are voluntary and unpaid.”
Prof Tom Sanders: “Member of the Science Committee British Nutrition Foundation. Honorary Nutritional Director HEART UK.
Before my retirement from King’s College London in 2014, I acted as a consultant to many companies and organisations involved in the manufacture of what are now designated ultraprocessed foods.
I used to be a consultant to the Breakfast Cereals Advisory Board of the Food and Drink Federation.
I used to be a consultant for aspartame more than a decade ago.
When I was doing research at King’ College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks. In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.”
Prof Sarah Berry: “Chief scientist at ZOE Ltd, options and consultancy at ZOE Ltd.”
Prof Keith Frayn: “I have no commercial interests related to this topic. I am the author of books on metabolism including ‘A Calorie is a Calorie’, Piatkus, Jan 2025.”
Prof Amanda Daley: “I have no direct conflicts to declare. I have conducted food labelling studies myself and I have received government funding to conduct health based research. I have never received any funding directly or indirectly from any food based industry partner.”
Toby Lasserson: “Cochrane Library has published and continues to publish reviews in the area of calorie purchasing based on different study designs to that used in the survey.”