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Traffic light labelling of meals for health and sustainability

In two experiments where participants were asked to choose between hypothetical canteen meals, “traffic light labelling” (red, amber or green labels) of different meal options was found to shift meal choices towards those lower in carbon emissions and calorie content.

When additional information was provided beyond simple traffic light labels, greater shifts towards lower-carbon meal choices were seen than when only the traffic light labels were provided. However, there was no significant difference in the choices made when general additional information (such as acceptable levels of daily carbon emissions or calorie consumption) was provided versus when more specific additional information (reference values to put figures on emissions and calories into a more understandable context) was provided.

As the authors note, the study is limited in that consumers might not make the same choices in a real canteen as they did in the experiment. Furthermore, no information on the price of the meals was provided to participants, while choices are also likely to have been affected by whether participants expected they would like the taste of the meal. The first experiment was limited to English speakers (recruited online), and the second experiment was further limited to UK citizens born in the UK. Both experiments excluded vegan participants as none of the meal choices were suitable for vegans.



The focus of the present study is to examine the impact of behavioral interventions designed to encourage consumer change around food choices in line with more sustainable consumption as well as healthy eating. More specifically, as a potential method of persuasion, we test the effect of the provision of information using traffic light labelling attached to different meal options signalling their impact on the environment (e.g. carbon emission levels) as well as on their health (e.g., calorific content). While traffic light labelling has shown some success in encouraging both healthy and sustainable food consumption, there is still limited work demonstrating the impact on choice behavior. The present study includes two experiments (Experiment 1, N = 120 [approximately 40 per condition], Experiment 2, N = 297 [approximately 95 per condition]). They examined the impact of the presentation of single (traffic light labelling of calorific content, traffic light labelling of carbon emission levels) and dual (both calorific content and carbon emission levels) traffic light labels in a hypothetical simulated canteen environment. For some participants, the traffic light labels were supplemented with additional information which either contained general information regarding calorific content and carbon emissions, or specific reference values regarding the relationship between particular calorific or carbon emission levels to other activities (i.e. walking, driving). The Results from both experiments show that, compared to baseline, the presence of traffic light labels led to positive shifts towards lower carbon emission and lower calorific content meals. Both general and specific information supported positive behavioural change towards healthier and sustainable meal choices. The findings are discussed in relation to existing work examining the impact of behavioral interventions designed to support positive change in consumer behaviour.



Osman, M. and Thornton, K., 2019. Traffic light labelling of meals to promote sustainable consumption and healthy eating. Appetite 138, pp.60-71.

Read the full paper here. See also the Foodsource resource What interventions could potentially shift our eating patterns in sustainable directions?


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