Approximately 63% of adults in the UK are living with excess weight. These conditions are partly the result of food environments that make it increasingly difficult to eat healthily. Price promotions represent a key aspect of these food environments and in the UK they are disproportionately applied to unhealthy products that are high in fat, sugar and salt.
There is good evidence to suggest that price promotions can affect the type and quantity of selected foods. Removing promotions from discretionary unhealthy products could therefore contribute towards promoting healthier diets. While these policies aim to ensure that consumers are not nudged into spending more money on unhealthy foods, they may be framed as exacerbating challenges related to rising costs of living and receive significant public opposition. That is why we aimed to generate early evidence on the effectiveness of an alternative policy approach, one which would allow price changes but restricts the communication of these changes to consumers through signage or packaging.
What’s in the report
This report summarises a proof-of-concept randomised controlled trial that we conducted to assess the potential impact of this policy on the number of calories purchased in a simulated online supermarket. In our study, a nationally representative sample of 8,361 people were randomly allocated to complete a hypothetical food order on one of three versions of a simulated supermarket:
- Control condition: price promotions on discretionary unhealthy items and communication of these discounts.
- Treatment 1 condition: discounts on discretionary unhealthy items, but no communication on these discounts (e.g. removal of stickers saying ‘£X off’).
- Treatment 2 condition: no discounts on discretionary unhealthy products.
Our primary outcome was to see if any of the conditions significantly affected how many calories people purchased.
Findings
In this study, we found no significant difference between study conditions for total calories ordered in the hypothetical shopping task.
Some results of this simulated supermarket study contradict those from real-world evidence. Specifically, in our study we find no impact of removing discounts from unhealthy products, while previous real-world research suggests that this effect is relatively well established. This discrepancy raises questions about the extent to which the overall results of our study are likely to be applicable to the real world.
In this report we discuss reasons why simulated environments might represent a promising setting to generate proof-of-concept evidence for some types of health interventions, but might be less conducive to generate valuable evidence for other interventions, such as those focussing on price. Due to the uncertainty about the real-world applicability of the results, we caution against making policy recommendations solely based on this study.
Authors
Nesta
Darren Hilliard, Frances Bain, Hugo Harper
Behavioural Insights Team
Ailidh Finlayson, Steve Human, Benji Horwell, Elena Meyer zu Brickwedde, Jordan Whitwell-Mak, Dr Giulia Tagliaferri, Dr Bobby Stuijfzand
Behavioural Insights Team & Nesta
Dr Filippo Bianchi
