Grocery Assistance Program Study (GAPS)

Designing a Food Benefit Program to Optimize Diet Quality for Obesity Prevention

This highly innovative experimental trial is designed to examine the independent and joint effects of prohibiting the use of SNAP-like benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more healthful foods.

Study Overview

• Status: Completed
• Conditions: Food Assistance
• Intervention / Treatment: Behavioral: F&V Bonus; Behavioral: Restriction; Behavioral: Bonus & Restriction

Detailed Description

More than 1 in 10 Americans participate in the Supplemental Nutrition Assistance Program (SNAP), a Federal food and nutrition program administered by the United States Department of Agriculture (USDA). SNAP, formerly known as the Food Stamp Program, provides funds to low-income families for the purchase of food. Benefits are provided on an electronic benefits transfer (EBT) card that is used like an debit card at stores.

In recent years there has been growing recognition that SNAP participants are disproportionately obese, with poor diet contributing to this disparity. In response, there is great interest in considering ways in which SNAP may better meet its objective to help people and families buy the food they need for good health.

Modifications to SNAP currently under evaluation involve offering incentives to encourage participants to purchase more nutritious food items. There is concern, however, that this strategy alone may be of limited usefulness in improving the nutritional quality of the diet for obesity prevention because incentivizing the purchase of more nutritious foods does not necessarily reduce the purchase of less nutritious foods (substitution effect may not occur) and may even increase the total calories purchased.

An alternative strategy that has been extensively discussed by public health advocates and policy makers in recent years is prohibiting the purchase of less nutritious food items with SNAP benefits. Commonly consumed foods that are high in discretionary calories (defined as calories from solid fats, alcohol, and added sugars) are prime targets for exclusion because SNAP participants consume far more energy from discretionary calories (43%) than recommended. This strategy may be particularly effective if implemented in conjunction with incentives for the purchase of more nutritious foods.

No studies have been conducted to evaluate whether prohibiting the purchase of foods high in discretionary calories with SNAP benefits may improve diet quality and reduce risk of obesity. Likewise research is lacking on the effect of effect of pairing restrictions with incentives. Thus, we propose to pilot a highly innovative experimental trial designed to examine the independent and joint effects of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more healthful foods. Key indicators of feasibility will include recruitment and retention (are targeted number of participants recruited and retained at a high rate?); fidelity of the intervention (are compliance measures successfully collected and do they indicate close compliance with experimental condition assignment?); and completeness of baseline and follow-up data.

Using study data, analyses will be conducted to evaluate the independent and joint effects of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods.

• Study Type: Interventional
• Enrollment (Actual): 296
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Minnesota
    • Minneapolis, Minnesota, United States, 55454
      • University of Minnesota School of Public Health

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• ≥ 18 years of age
• Primary food shopper of household
• Not currently participating in the Supplemental Nutrition Assistance Program (SNAP)
• Not planning to apply for SNAP in the next 4 months
• Able to read and write in English
• ≤ 8 people living in household
• Have a gross monthly income level that places the household at or below 200 percent of the Federal poverty level for their household size.

Exclusion Criteria:

• < 18 years of age
• Not primary food shopper of household
• Currently participating in the Supplemental Nutrition Assistance Program (SNAP)
• Planning to apply for SNAP in the next 4 months
• Unable to read and write in English
• > 8 people living in household
• Have a gross monthly income level that places the household above 200 percent of the Federal poverty level for their household size

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control; Usual SNAP-like food benefits
Experimental: Rewards; Usual SNAP-like food benefits, plus a modification to this food benefit program that entails a 30% bonus on eligible fruit and vegetable purchases (i.e. F&V bonus)	Behavioral: F&V Bonus; To examine the independent effect of offering an incentive (i.e. bonus dollars for fruit and vegetable purchases) to SNAP-like benefits to encourage the purchase of more healthful foods
Experimental: Restrictions; Usual SNAP-like food benefits, plus a modification that requires no sugar-sweetened beverages, candy, or sweet baked goods be purchased	Behavioral: Restriction; To examine the independent effect of prohibiting the use of SNAP-like benefits to purchase foods high in discretionary calories (i.e.sugar-sweetened beverages, candy, or sweet baked goods) on food purchases and diet quality
Experimental: Rewards plus restrictions; Usual SNAP-like food benefits, plus two modifications to this food benefit program: one modification includes a 30% bonus on eligible fruit and vegetable purchases and the other modification is that sugar-sweetened beverages, candy, or sweet baked goods are not allowed to be purchased (i.e. Bonus & Restriction)	Behavioral: Bonus & Restriction; To examine the joint effects of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more healthful foods

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in Total Kilocalorie intake at 16 weeks	Evaluate the independent and joint effects on dietary intake of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods.	16 weeks
Change from baseline in reported levels of household food security at 16 weeks	Assessing any change from baseline in the score of the The U.S. Household Food Security Survey Module: Six-Item Short Form	16 weeks
Change from baseline in Healthy Eating Index (HEI) Score at 16 weeks	Evaluate the independent and joint effects on dietary intake of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods. More information about the HEI score can be found here: http://nccor.org/projects/hei/	16 weeks
Change from baseline in daily servings of fruits and vegetable (added together) at 16 weeks	Evaluate the independent and joint effects on dietary intake of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods. Servings of fruits and servings of vegetables are calculated from the output provided by NDS-R, which are based on the reported food intake as collected via 24-hour dietary recalls. Three recalls are collected at baseline and averaged; three recalls are collected at follow-up and averaged.	16 weeks
Change from baseline in daily total, in grams, of added sugars at 16 weeks	Evaluate the independent and joint effects on dietary intake of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods.	16 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in Body Mass Index	Evaluate the independent and joint effects on Body Mass Index of prohibiting the use of SNAP benefits to purchase foods high in discretionary calories and offering an incentive to encourage the purchase of more nutritious foods.	16 weeks

Collaborators and Investigators

• Sponsor: University of Minnesota
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Investigators: Principal Investigator: Lisa J Harnack, DrPH, University of Minnesota

Publications and helpful links

General Publications

• Valluri S, Mason SM, Peterson HH, French SA, Harnack LJ. The impact of financial incentives and restrictions on cyclical food expenditures among low-income households receiving nutrition assistance: a randomized controlled trial. Int J Behav Nutr Phys Act. 2021 Dec 4;18(1):157. doi: 10.1186/s12966-021-01223-7.
• French SA, Rydell SA, Mitchell NR, Michael Oakes J, Elbel B, Harnack L. Financial incentives and purchase restrictions in a food benefit program affect the types of foods and beverages purchased: results from a randomized trial. Int J Behav Nutr Phys Act. 2017 Sep 16;14(1):127. doi: 10.1186/s12966-017-0585-9.
• Harnack L, Oakes JM, Elbel B, Beatty T, Rydell S, French S. Effects of Subsidies and Prohibitions on Nutrition in a Food Benefit Program: A Randomized Clinical Trial. JAMA Intern Med. 2016 Nov 1;176(11):1610-1618. doi: 10.1001/jamainternmed.2016.5633. Erratum In: JAMA Intern Med. 2017 Jan 1;177(1):144.

Helpful Links

• Brief Study Description & Study Contact Information

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2013
• Primary Completion (Actual): May 1, 2015
• Study Completion (Actual): March 1, 2016

Study Registration Dates

• First Submitted: December 22, 2014
• First Submitted That Met QC Criteria: December 28, 2015
• First Posted (Estimate): December 31, 2015

Study Record Updates

• Last Update Posted (Actual): October 24, 2017
• Last Update Submitted That Met QC Criteria: October 20, 2017
• Last Verified: October 1, 2017

More Information

Terms related to this study

• Other Study ID Numbers: DK098152; R01DK098152 (U.S. NIH Grant/Contract)