Fixing Food Deserts: Promising or Trivial Effects?

It seems to be an article of faith. Millions of low-income Americans live in food deserts and it puts them at higher risk for obesity. That’s a prevalent narrative to explain the link between poverty and obesity. And thus, the narrative works its way into the interpretation of research on programs for fixing food deserts.

Two recent publications in JAMA Pediatrics make this pretty clear.

A Quasi-Experimental Cohort Study

FRESH is the clever acronym of a program for fixing food deserts – Food Retail Expansion to Support Health. Pasquale Rummo, Jeremy Sze, and Brian Elbel used a difference-in-differences approach in analyze effects of this program. So they studied public school students in New York City living within a half mile of a FRESH supermarket opening. Students living farther away from those openings made up their control group.

Previous studies found no change in food purchasing patterns or dietary quality associated with the program. But nonetheless, they pressed on with a new analysis of BMI z scores for a new publication in JAMA Pediatrics. Their persistence rewarded them with the finding of a statistically significant difference favoring children living near a new FRESH supermarket. Though they concede that this relationship is an association and not definitive evidence of cause and effect, they conclude:

Government-subsidized supermarkets may contribute to a small decrease in obesity risk among children residing near those supermarkets, if part of a comprehensive policy approach.

“Trivial or Zero Effects”

Writing in an editorial alongside this new study, Sarah Deemer, Arthur Owora, and David Allison express a very different view. This is because the observed effect size is so small in comparison to existing criteria for credibility. In the context of previous negative findings for this same program, they conclude:

“In summary, our reading of the results of this study is that they are far more consistent with trivial to zero effects than promising ‘effects.’”

Prevailing Narratives

Prevailing narratives prevail. After years of looking for an effect from dropping supermarkets into “food deserts,” the best we can find is a possible trivial effect. But people can’t seem to let go of this seductive metaphor.

So maybe it’s time to dial up our curiosity. Because prevention programs with trivial effects have not taken us very far in preventing obesity. In fact, obesity just keep growing while we push ineffective strategies to “battle” it. Now is the time to seek better strategies. Strategies that work.

Click here for the study and here for the editorial.

Desert, painting by Martiros Sarian / WikiArt

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May 24, 2022