The Lunch of the Little Ones

Is Better School Nutrition Helping with Obesity?

Among folks concerned with obesity, nutrition, and health for kids, the Healthy Hunger-Free Kids Act (HHFKA) is a bright spot in the list of accomplishments on school nutrition. But until now, there was little evidence that this or anything else that fell under the umbrella of Let’s Move! had done much to move the needle on obesity in young persons. A new report in JAMA Pediatrics this week points to the possibility of a small effect. In an editorial alongside the study, Lauren Fiechtner, Jennifer Woo Baidal, and Erika Cheng express encouragement about these results:

“Similar to other national reports, they found statistically significant decreases in BMIz among adolescents and children living in poverty. However, they also demonstrate improvements in BMI within the entire cohort of school-aged children.”

But along with this comes a note of caution: “More than one policy change is needed to reduce inequities in food insecurity and obesity.” Plus, “the effect sizes of BMI change in this study were relatively small.”

An Association with a Better Trend

This was a carefully conducted cohort study using data from the Environmental Influences on Child Health Outcomes program. The primary outcome was the trend of annual measures of BMI z-scores from January of 2005 to March of 2020. In the period after implementation of the HHFKA, they found a small, statistically significant decrease in BMI z-scores for all kids of school age and also for kids from low-income households.

Of course, this study is observational and the authors are clear that they cannot rule out the possibility of residual confounding. Observation of a change in trend before and after an event is not proof that the event caused the change. Professor Andrew Brown at the University of Arkansas explains:

“Despite the strengths of the study, the design leaves us with the very real possibility that something else happened over that time frame (or even years before) that could explain the difference.”

More Than Nutrition

No doubt, improved nutrition in schools is important progress for reasons that go well beyond the possibility of a small effect on obesity trends. But the relentless upward trends in obesity, both for children and adults, comes from more than just problems with our food systems. And, as the authors of the editorial note, it will take more than improvements in school nutrition to fix it.

Click here for the study, here for the editorial, and here for perspective on the need for a broader view.

The Lunch of the Little Ones, painting by Pierre Bonnard / WikiArt

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February 16, 2023