We chose the paper on impact of calorie labelling on fast food purchases for the first Journal Club discussion out of a number that had been suggested. It met one of our key criteria, that it was easily accessible (not requiring institutional subscription). There also seemed to be good scope for discussion from a wide range of people with interests in research; behaviour change; and policy in relation to public health. Finally, we had decided to proceed through a succession of study designs in our journal club choices, so that overall participants will be able to weigh up the potential benefits and disadvantages of different types of study as evidence in public health. The calorie labelling study used a cross-sectional survey design.
The transcript of the discussion can be accessed here. There was some consensus within the discussion, that the design of the study was problematic in relation to the research questions, and therefore that the results were not meaningful. Critique focused on these key areas:
- a lack of consistency between cohorts (including in the questions asked);
- manner of approach by researchers may have impacted on food choices; and on answers to questions (e.g. about use of calorie info)
- lack of exploration of how the customers made choices /used info.
- difficulty of disentangling the effects of other factors that changed over the period between the studies (particularly, changes to menus and the proportion of higher/lower calorie foods offered)
Discussion participants spent some time contributing possible alternative designs that might give better evidence about the impact of fast food restaurants’ calorie labelling on customers’ food choices, although it was acknowledged that these might bring their own difficulties (recruitment; expense). There were a number of ideas about how a longitudinal cohort study might be designed/ recruited to and maintained (better, because gives evidence on how individuals’ choices change over time); and also suggestions about an RCT design in this area.
There was also however, interesting discussion about the findings and observations. In part 2 of the study (after implementation of calorie labelling legislation in New York City), only 15% of customers surveyed claimed to have used the calorie information when making their choices. This seemed to be very low in terms of policy impact; especially given that it seemed likely that participants might ‘exaggerate’ their use of the info. We discussed the possibility that the policy had had an impact such that the calorie/health-conscious were staying away from the fast food chains (and therefore would not be captured in the second part of the study design). Alternatively (or additionally), is the main customer base for those chains simply not very interested in ‘making healthier choices’ (fast food as a treat)? Finally, there is the issue (that the authors highlight) of the public having the skills to interpret calorie information – do such interventions need to be accompanied by clearer health education messages about calorie values?
It is likely that fast food chains will promote calorie information in other countries in future – some already do this, for example in the UK – although without legislation and enforcement. This study does not give clear evidence about whether it has any effect on food choices (and ultimately, by extension, on public health). It may, however, help the large fast food chains promote their ‘responsibility’ and thereby maintain their customer base; as well as making for better-informed customers. The study did seem to indicate that the available menu options in a restaurant had more influence on the calorific value of customers’ food choices than did calorie labelling per se. Therefore, the nature of the food ‘offer’ itself is perhaps a more important area in which to focus public health policy efforts. Finally, it needs to be acknowledged that overall food intake and accessibility are much wider issues; enabling healthier food choices should involve a very wide range of interventions – not just fast food menus.