The formation and malleability of dietary habits: A field Experiment with Low Income families

Last registered on October 04, 2018
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Pre-Trial

Trial Information

General Information

Title
The formation and malleability of dietary habits: A field Experiment with Low Income families
RCT ID
AEARCTR-0003281
Initial registration date
August 31, 2018

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
October 04, 2018, 10:14 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country
United Kingdom of Great Britain and Northern Ireland
Region

Primary Investigator

Name
Michele Belot
Affiliation
University of Edinburgh
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Other Primary Investigator(s)

PI Name
Jonathan James
PI Affiliation
University of Bath
Contact Investigator
PI Name
Valeria Skafida
PI Affiliation
University of Edinburgh
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PI Name
Noemi Berlin
PI Affiliation
Universite de Paris Nanterre
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Additional Trial Information

Status
On going
Start date
2015-02-15
End date
2018-12-31
Keywords
Governance
Additional Keywords
Dietary choices, obesity, habit formation
JEL code(s)
I12, I14
Secondary IDs
Abstract
We will conduct a randomized controlled experiment targeting a sample of 300 low-income families with young children (with at least one child between 2 and 6 years old). The interventions aim at encouraging low-income families to break unhealthy dietary habits and adopt healthier ones for a period of 12 weeks. We aim at studying the long-term effects of these interventions.

The interventions will be conducted following a randomised control trial protocol, whereby a third of the sample will be assigned to each of the treatments and the remaining third will serve as a control group. We will study short and medium term effects of the intervention by following people over time and collecting information on dietary choices and health outcomes, including body weight, height, and health biomarkers.

We will collect information before, during and after the intervention (each year after the intervention for a period of 3 years).

The effects will be estimated using a difference-in-differences approach, i.e. comparing variables of interest (dietary choices, preferences and health biomarkers) for the treated groups to those observed in the control groups. The goal here will be to document the average treatment effect on diet and health.

External Link(s)

Registration Citation

Citation
Belot, Michele et al. 2018. "The formation and malleability of dietary habits: A field Experiment with Low Income families." AEA RCT Registry. October 04. https://doi.org/10.1257/rct.3281-1.0
Former Citation
Belot, Michele et al. 2018. "The formation and malleability of dietary habits: A field Experiment with Low Income families." AEA RCT Registry. October 04. https://www.socialscienceregistry.org/trials/3281/history/35292
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
We will implement two interventions:
The first intervention consists of providing food and recipes directly at home for a period of 12 weeks for a main family meal for 5 days a week.
The second intervention will last for the same period (12 weeks). We will test the impact of regular versus irregular rewards (sweet energy-dense snacks, <200 calories per item). A third of the sample will be assigned to a regular snacking protocol, consisting of 3 meals at regular times during the day and no snacks between meals, except for one day a week, chosen by families). Children will be allowed to consume an additional healthy snack in the morning and the afternoon (that we will provide using a private partner). The snacks provided are again approved by our nutritionist. A meal is defined as food and beverage consumption of >200 kcal consumed without interruption during a defined period (up to 1h). Treats are defined as energy-dense snacks of <200 kcal/item and consumed in isolation from other foods.

Intervention Start Date
2015-03-05
Intervention End Date
2015-12-04

Primary Outcomes

Primary Outcomes (end points)
Body mass index of children and parents
Measures of food preferences (self reported), based on 20 items (Food Preference Questionnaire) grouped in categories (fruit, vegetables, sweets, cheese, bread, processed foods, meat/fish/eggs, as well as 5 meals that were part of the first intervention)
Measures of dietary intake (calories, fruit and vegetable consumption, macro-nutrients: (saturated) fat, sugar, added sugar (NMES), protein, fibre, carbohydrates)
Primary Outcomes (explanation)
The food preferences will be based on our Food Preference Questionnaire, we will average preferences (reported on a scale from 1 to 4) across foods belonging to the same category.
The dietary intake measures will be based on grams Or Kcal (for calories) and will be constructed using a nutrition software (WISP and INTAKE24)

Secondary Outcomes

Secondary Outcomes (end points)
Health biomarkers based on blood samples for adults for the first year of the study (before and after interventions): NEFA (nmol/l), Insulin (nmol/l), Triglyceride (nmol/l), Glucose (nmol/L), HDL and LDL cholesterol (nmol/L), CRP (mg/L), Total Antioxydant Status
Incentivized measures of dietary preferences for children in year 3: Number of healthy choices in an incentivized task (with choices between pairs of two foods)
Incentivized measure of food preferences in years 2 and 3 for adults
Secondary Outcomes (explanation)
For the food preferences for adults, we will ask them to purchase a basket of foods worth 30GBP using a tool we developed: We will measure calories (Kcal), saturated fat (g) and sugar in the food basket chose. One family in 20 will receive the chosen basket at home 2-3 weeks after their participation to the session.

Experimental Design

Experimental Design
Sample: 300 families with at least one child between the age of 2 and 6 and an income below regional average will be recruited in the area of Edinburgh (wave 1) and Essex (wave 2).
The interventions will be implemented over the course of twelve weeks.
Measurements will be taken at the facilities of the University at baseline (pre-intervention), as well as post intervention (one week after, and then every year after baseline for 3 years). A mid-intervention session (at around 6 weeks of intervention) will also take place.
Experimental Design Details
Randomization Method
Days of university visit of participants at baseline are allocated to each treatment and Control (rolling over 21 days in Edinburgh and 14 days in Essex following the same sequence starting with Control, then each intervention). Participants are not informed ex ante of which day corresponds to which treatment. They pick a slot among all dates for the first session.
Randomization Unit
Family
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
300 families (with one child and at least one adult). The whole family is treated but measurements are only taken on adults (main adult and possibly a second one if present), and on one child (the youngest child of the family between the age of 2 and 6.
Sample size: planned number of observations
Between 300 and 600 adults, and 300 children (a third in Edinburgh - wave 1 and two-thirds in Essex - wave 2)
Sample size (or number of clusters) by treatment arms
Around 100 per treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Unknown
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Ethics Committee University of Edinburgh
IRB Approval Date
2015-01-08
IRB Approval Number
N/A
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials