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Nudges to improve healthy food consumption in large supermarkets
Last registered on December 02, 2020


Trial Information
General Information
Nudges to improve healthy food consumption in large supermarkets
Initial registration date
November 26, 2020
Last updated
December 02, 2020 12:33 PM EST
Primary Investigator
Departament of Economics School of Social Sciences
Other Primary Investigator(s)
PI Affiliation
Cornell University
PI Affiliation
Universidad de la República
PI Affiliation
Universidad de Montevideo
Additional Trial Information
Start date
End date
Secondary IDs
The aim of this project is to evaluate the use of nudges to improve households’ food choices towards healthier options in a real shopping framework. Data for the analysis come from a big supermarket that keeps track of purchases made by clients who are members of its loyalty program. We hypothesize that customers will improve the nutritious quality of food choices when provided with weekly messages reminding them about the importance of eating healthy food, suggesting simple ways to include them in the family’s menu, and encouraging them to take these tips into action. In particular, messages designed to highlight and promote the consumption of fruits, vegetables, grains, seeds, nuts, legumes and fish, and cooking at home, are expected to have an impact on the composition of grocery purchases, increasing items promoted and reducing less healthy food choices.
External Link(s)
Registration Citation
Balsa, Ana et al. 2020. "Nudges to improve healthy food consumption in large supermarkets." AEA RCT Registry. December 02. https://doi.org/10.1257/rct.6321-2.0.
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Experimental Details
We send text messages to frequent buyers of a large grocery store with the aim of promoting healthy food consumption among consumers and changing purchasing patterns towards healthier products. The messages combine the delivery of relevant nutritional information in small doses with simple tips and suggestions (including video recipes) to facilitate the incorporation of healthier habits. The design of the messages aims at reoptimizing consumers' choice architecture by counteracting the influence of present bias, cognitive fatigue, and unhealthy environments. We send messages 3 times a week for 9 weeks.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Purchases of promoted (healthy) and non-healthy food choices. Healthy items that were promoted in the intervention include fruits, vegetables, grains, seeds, nuts, legumes, and fish.
Primary Outcomes (explanation)
We will construct an aggregate index quantifying the nutrition content of food purchases.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Customers within the “best customers” and “best customers with potential” categories were contacted by the supermarket by email. They were invited to give an informed consent and asked to fill a short survey that provided basic data about family composition, consumption habits and products commonly purchased in the supermarket. Between September and November 2019 we recruited a large group of clients (group 1) and during June 2020 we recruited a second group of clients (group 2).

In both groups we randomized clients to a treatment and a control arm. Clients in the treatment groups received messages through WhatsApp over a period of nine weeks regarding the following subjects: cooking at home, vegetables, fruits, healthy snacks, mindful eating, legumes, fish, and healthy eating. Clients in group 1 received messages between June 13th and September 24th 2020, while clients in group 2 received messages between August 11th and October 8th 2020.
Experimental Design Details
Randomization Method
Randomization done in office using STATA.
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
2140 individuals
Sample size: planned number of observations
2140 individuals (supermarket clients)
Sample size (or number of clusters) by treatment arms
1074 assigned to treatment group and 1066 to control group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Comité de ética - Universidad de Montevideo
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)