October 30, 2019

expert reaction to study looking at calorie labels in fast food outlets in the US, and calories bought

A study, published in the BMJ, reports that calorie labels in fast food outlets are linked to a small drop in calories purchased.  

Catherine Collins RD FBDA, NHS Dietitian, said:

“With rising levels of UK obesity the main focus of the public health agenda is a change in eating habits towards an overall lower total calorie intake, with the expectation that alongside other lifestyle measures this will limit population weight gain and perhaps encourage individual weight loss.  Although ‘success’ can be claimed in reducing calories purchased from downsizing snack food portions or reducing the consumption of sugar sweetened beverages (SSB) with the introduction of the sugar tax, in reality these approaches have had zero influence on overall weight.  Such simple changes demonstrate the fluidity of purchasing habits, and how reducing calories from one particular food or drink item is often offset by increased calories from other choices.

“So this ambitious and interesting three year study, evaluating ‘before’ and ‘after’ purchasing habits from a US fast food chain after menus were amended to include calorie labelling, provides excellent data going forward for public health mandarins.

“Of interest was that the average calorie content per purchase was nearly 1500kcals – three quarters of the average daily calorie goal of 2000kcal per day.  The authors acknowledge that they had no way of checking whether a purchase was for single or shared consumption.  To compare, a large meal from a UK burger or chicken shop, together with a sugary drink and perhaps a dessert, would provide between 1100-1400kcals a serving.

“The authors attempted to control for external variables such as Christmas and Thanksgiving weeks, (typical periods of ‘indulgence’ – where calories-per-transaction were increased), the impact of Hurricane Harvey (where takings were down due to store closures and smaller customer base), and removed data taken around a ‘side’ item promotion (which proved the most popular promotion in the franchise history, and so skewed more typical purchasing habits).

“Their findings prove uncomfortable for those viewing calorie labelling at point-of-purchase as a means of influencing food choice.

“The initial 60kcal reduction per overall purchase was the calorie equivalent to a simple ‘skip-the-dip’ from a UK fast food outlet.  The authors note that with the advent of calorie labelling the initial drop in calories was more related to buying fewer items, not choosing lower calorie options.

“From an initial reduction in the purchase of ‘add on’ sides, over time the public returned to familiar purchasing habits, which meant by the end of three years the calorie deficit achieved decreased to a meaningless 10kcal per purchase – from (1494kcal to 1484kcal).

“Hearteningly, with the advent of simple calorie labelling, rather than taxation, sugary drinks purchases fell over the three year period to 61% of the pre-labelling sales, which represents a major change in purchasing habits.

“Was labelling the reason for the reduction in sugary drinks?  If so, it would be expected to generate a rise in low calorie substitutes.  Interestingly, sales of sugar free drinks also fell in the post-labelling period by an even greater amount – to 47% of pre-labelling sales.  This highlights how difficult it is to predict changes in purchasing habits at point-of-source purchase.  It isn’t possible to interpret whether incentives to add drinks to meal choices were altered, whether the data reflected a change in customer habits (e.g. ‘eat in’ versus drivethrough/take-away) – or that customers were simply less thirsty.

“The limitations of the study are many, and well defined by the investigators.  Overall this was impressive research carried out by the investigators and the fast food franchise who gave access to purchasing date.  It demonstrates the significant calorie contribution that take-aways add to consumers diets, and confirms that simple point-of-sale calorie labelling has little influence on altering food habits (although appeared to reduce overall drinks sales).  This is not surprising, as I’d predict only a small minority of fast food consumers would use the information as part of their active attempt to lose weight – with many dieters avoiding the temptation of eating at such establishments in the first place.

“This research confirms that whilst a fast food outlet can provide food and drink providing both low and higher calorie options, and offer food labelling to inform and direct consumer choice, whether this information is used to amend purchasing habits and alter food choices is ultimately down to personal preferences of the consumer.”

Dr Amelia Lake, Professor in Public Health Nutrition, Teesside University, and Registered Dietitian, said:

“This is a large well-designed study in the US showing the effects of calorie labelling in a single fast food chain across multiple stores.

“It is interesting in this country because this is something that is being considering as a public health intervention.

“What this shows us is that this alone (i.e. calorie labelling) is not a solution in itself.  Obesity is a complex condition and therefore needs a multifaceted approach to tackle it.  Our food environment determines what food we eat.  We can make changes to the environment to help the population make healthier choices.  Calorie labelling is one of these methods that can be use alongside a suite of other measures to help everyone have a healthier diet.

“In our research we have worked with local fast food outlets to look at changing the size of the packaging as well to look at cooking methods e.g. the type and the amount of times oil is used.”

‘Estimating the effect of calorie menu labeling on calories purchased in a large restaurant franchise in the southern United States: quasi-experimental study’ by Joshua Petimar et al. was published in the BMJ at 23:30 UK time on Wednesday 30 October 2019. 

DOI: 10.1136/bmj.l5837

Declared interests

Catherine Collins: “No conflict of interest declared.”

None others received.