Nudging healthy food choices through e-messages in a supermarket

This paper analyses the impact of a healthy food nudge intervention on purchases of 1590 customers of a supermarket chain's loyalty program in Uruguay through a randomized controlled trial. Nudges were presented in the form of messages sent through WhatsApp to customers three times a week for 8 weeks (between July and September 2020). Messages highlighted the benefits of cooking at home and eating mindfully and healthy (vegetables, fruits, healthy snacks, legumes, and fish), and included easy to implement tips. Results show that, on average, customers assigned to the treatment group increased their purchases of healthy food by 8% and substituted sugar-sweetened for sugar-free beverages. We find an unintended increase in purchases of unhealthy food of 7%, with no correlative increase in calories, suggesting that customers substituted higher calorie products for lower calorie ones. We find that households with lower educational attainment, lower income, and with children under the age of 12 are more likely to increase purchases of fruits and vegetables, while other households are more likely to improve the diet quality without increasing expenditure. Effects do not persist after the intervention is over, suggesting that salience, rather than information is the main channel triggering the effects.