Calorie food labelling only part of the picture in tackling poor diets
Reading the number of calories in food in a supermarket or on a restaurant menu might nudge you to make a ‘better’ food choice, but is it enough to change the way we eat and live healthier lives?
Calorie labelling on prepackaged foods and menus only has a small effect on food choices for each person, but the effect on a national level could be significant, suggests a review of the latest evidence that highlights the complexities of tackling diet and public health.
Poor diets, including the overconsumption of saturated fats, sugar and salt, contribute to increasing obesity rates and, alongside the consumption of alcohol, play an important role in the development of illnesses such as heart disease, diabetes and many cancers, say Gareth J. Hollands, PhD, from the Behaviour and Health Research Unit at the University of Cambridge, UK, and colleagues.
They highlight that 2.8 million people are estimated to die every year around the globe as a result of diseases caused by obesity, with the most disadvantaged people in high-income countries the hardest hit.
Aside from the impact on health, that has a huge economic cost. The UK Department of Health estimated recently that obesity costs the UK National Health Service £6 billion (US$7.76 billion) annually, a figure which is expected to rise to over £9.7 billion ($US12.55 billion) each year by 2050.
Changing your food habits is hard
“However, changing diet- and alcohol-related behaviours to halt and reverse rises in these potentially preventable diseases is difficult,” the researchers say. “While many people want to engage in behaviours that promote good health, most find it difficult to implement and maintain them.”
This is partly because the places where they choose and buy food can have a “considerable influence” on their routines, and so “altering these environments appears a promising approach” in aiding people to maintain good habits.
Nutritional labels are intended to help people make informed choices over what they eat, particularly for prepared or prepackaged foods, which typically contain a mix of ingredients that make it difficult for consumers to know their nutritional or energy content.
These labels have become mandatory in many regions around the world, including the UK, USA, the European Union, Canada, Australia and New Zealand, and several countries in Asia and South America. However, whether they work as a means of altering consumer behaviour is another question.
Real-world studies
To find out, researchers performed a review in 2018 of the evidence that was available at the time but the results, based on just three randomised controlled trials (RCTs, considered the gold standard when it comes to comparing to different approaches), were inconclusive.
Since then, a wealth of studies and reviews have been published, greatly expanding the pool of data the researchers could draw on. They therefore looked for a range of different studies, including RCTs, published in medical journals and included in registries of trials, among other sources, up to September 2023.
They identified 25 studies, including 18 RCTs, that were suitable for analysis, of which 23 concentrated on food labelling and two on both alcohol and food labelling. Fifteen studies were carried out in the USA, with six in the UK, one in Ireland, one in France and another in Canada. The majority (18 studies) included people with a high socioeconomic status, but only one focused only on the most disadvantaged groups in society.
Thirteen of the studies were conducted in real-world settings, such as in restaurants, cafeterias or supermarkets, while six were carried out in laboratories that mimicked those environments. The most commonly studied type of labelling, in 20 studies, was a simple calorie label, while others assessed calorie labelling with information about at least one other nutrient.
A small change for you but a giant leap for society?
When looking at how calorie labelling affected the choices that people made when selecting foods, the researchers found that it led to only a small reduction in the energy levels of the foods they chose.
For an average meal of 600 kcal, adults exposed to calorie labelling would select 11 kcal less (equivalent to a 1.8% energy reduction) than those choosing foods without labelling, and consume 35 kcal less (equivalent to a 5.9% energy reduction).
While this might not have much of an effect on an individual level, the researchers believe the reductions they saw could have “potentially meaningful impacts on population health when applied at scale,” although they note that studies are needed to assess the impact of factors that could affect food choices, in particular socioeconomic status.
As for alcohol calorie labelling they note that, with only two studies available for analysis, there is “insufficient evidence” to draw any conclusions.
The research was published by the Cochrane Database of Systematic Reviews on January 17.
It’s about more than just calories
“Given that larger takeaways, restaurants, and cafe food outlets in England have recently implemented legislation by providing calories on their menus, it great to see that this new evidence review supports that there is some effect of this information on reducing the amount of energy consumers select,” commented Sally Moore, RD, PhD, Lecturer in Nutritional Science, University of Leeds, Leeds, UK.
“However, given alone, the energy (calorie) content of food products does not tell us about other nutrients which we may need to consider in healthier eating, and often eat more of than recommended, including saturated fat, sugars and salt.”
Hilda Mulrooney, PhD, Reader in Nutrition & Health, London Metropolitan University, London, UK, agreed that the study’s findings are “important,” and show the role that nutrition labels can play in providing “guidance for consumers to help them make informed choices and to compare options for purchase and consumption.”
“Nonetheless, the authors are clear that energy labelling alone will not ‘solve’ the problem of chronic disease, and further research is needed in particular to understand potential downsides, including disordered eating.”
Tom Sanders, DSc, PhD, Professor emeritus of Nutrition and Dietetics at King’s College London (KCL), London, UK, also pointed out that it is “well known that consumers get fatigue from calorie labelling in the long term, particularly for regularly purchased products.”
Added sugars and ultra-processed foods
This gets to the heart of what is a complex picture of how people choose food, and the ways in which food manufacturers respond to legislation to better inform consumers through labelling.
For example, the UK government introduced a tax on sugar-sweetened drinks—ie, had sugar, including honey or syrups, added during production—that came into effect in April 2018. Rather than have their drinks labelled as containing high levels of added sugar and pay additional tax, manufacturers responded by significantly decreasing the sugar and energy content of their carbonated sugar-sweetened soft drinks.
A win for public health but perhaps less so for the public purse.
And of course it is possible for foods and drinks to be low in calories and still be detrimental to health. Ultra-processed foods (UPFs), such as potato chips, frozen pizzas and even many types of supermarket breads, have been linked to obesity, diabetes, and high blood pressure to depression, anxiety and autoimmune disorders, including psoriasis.
Earlier this year, the US Food and Drug Administration announced a proposal to introduce a front-of-package (FOP) nutrition label for the majority of packaged foods that provides information on the saturated fat, sodium and added sugar content, ranked as “Low,” “Med” or “High” levels of these nutrients.
Foods in France already have an FOP Nutri-Score label that ranks food products from A (healthiest) to E (least healthy) based on their nutritional quality, a system that has been adopted voluntarily by other countries, including Belgium, Germany, Luxembourg, the Netherlands, Spain and Switzerland.
In the UK, there is currently no requirement for packaged or any other kind of UPF to have an FOP or additional label other than the standard nutritional label. However, the government encourages consumers to follow their Eatwell Guide, which shows how much of what we eat should come from each food group to achieve a healthy, balanced diet.
Which brings us back to that tried and tested food advice, handed down from generation to generation, that moderation is the key, and a little bit of what you like does you good.
The production of the review was funded in part by a Collaborative Award in Science from the Wellcome Trust.
No relevant financial relationships declared.
Liam Andrew Davenport is a medical reporter with more than 20 years’ experience covering a wide range of specialties and topics in the field.