Why America’s Obesity Problem Is About Junk Food, Not Cost

A common narrative regarding the obesity epidemic in the United States suggests that the primary driver is the high cost of healthful foods compared to the affordability of junk food. However, recent research and analysis suggest that financial barriers may not be the central cause of poor dietary choices.

In a column published on May 1, 2026, Tamar Haspel of The Washington Post highlighted a study from Duke University that challenged the assumption that providing free produce significantly improves health outcomes for those at risk of food insecurity.

The Duke University Produce Prescription Study

The Duke University study focused on patients with Type 2 diabetes who were at risk of food insecurity. Participants in the study had an average Body Mass Index (BMI) of 36, a figure classified as obese.

Researchers implemented a produce prescription program, providing one group of participants with a debit card containing $80 per month specifically for the purchase of legumes, vegetables, or fruits. All participants received standard diabetes care information, while the control group did not receive the debit card.

The study’s objective was to determine if removing the cost barrier to fresh produce would improve the participants’ diets and subsequent health metrics. However, the results did not support this hypothesis.

After 12 months, the group receiving the produce prescription showed slightly higher blood-sugar levels than the control group. Other key health measurements, including blood pressure, doctor visits, and BMI, remained the same between the two groups.

Analysis of Participant Behavior

The most significant finding of the study was not the health metrics, but the actual usage of the provided funds. According to the report, only 30% of participants used at least 80% of the $80 monthly allowance.

This suggests that even when fruits and vegetables are provided free of charge, a majority of the target population does not utilize them. This finding supports the argument that preference and taste, rather than cost, may be the primary drivers of obesity-related dietary habits.

“It surprised us. We didn’t hypothesize a null trial,” Connor Drake, Duke University

Drake, one of the study’s authors, noted that while the trial was a null result, such findings are critical for understanding what interventions are ineffective and providing clues for future research directions.

Broader Context and Other Research

The Duke study is not the only research to find limited success in cost-reduction interventions. Haspel noted a similar rigorous study published in 2023 involving Type 2 diabetes patients at risk of food insecurity.

In that 2023 trial, participants received healthy groceries for 10 meals per week for their entire household, supplemented by health coaching, nurse evaluations, dietitian consultations, and diabetes education. Despite these comprehensive supports, there were no significant differences between the participants and the control group after 12 months.

Other smaller-scale programs have reported modest improvements, though often lacking a control group for verification:

• A fruit and vegetable voucher program showed a small decline in blood sugar.
• A program providing 21 servings of fresh vegetables per week showed a small decrease in waist circumference.
• A study comparing a $40-per-month card against a produce box showed a small decline in blood pressure.

While some of these changes reached statistical significance, the overall impact across these trials is described as underwhelming.

Potential Confounding Factors

Researchers Connor Drake and Susan Spratt identified several factors that might have influenced the Duke study’s results. They suggested that the initial screening might not have captured households that were truly food-insecure.

the researchers noted that participants were not provided with assistance on how to incorporate the fruits and vegetables into their meals, and there may have been insufficient prompts or nudges to encourage the use of the debit cards.