Strong Beliefs and Stronger Analyses in Obesity

Often indirectly, but sometimes directly, we hear from true believers in concepts attached to obesity, nutrition, and public policy. The embedded question is “Why do you doubt this article of faith?” Among the many articles of faith in this realm is the belief that if we deliver just the right education or just the right nudges to people (or children) at risk for obesity, we will finally “tackle” the problem. It’s understandable. In fact, we see no problem with bringing strong beliefs to the subject of obesity, so long as we bring along even stronger analyses to test them.

An excellent case in point appears in the February issue of the Journal of Nutrition Education and Behavior. The initial analysis of a study of cooking programs found support for its effectiveness with children. But a stronger analysis showed that the effect was nil.

Exposure to Healthy Foods

The premise of this study was straightforward. Test the presumption that exposing children to healthy foods in a cooking program could nudge them toward more often choosing healthy foods afterward. Frans Folkvord, Doeschka Anschütz, and Marieke Geurts set up this experiment with 125 children between the ages of 10 and 12. They randomized the children for exposure to ten-minute video clips from a cooking program. The experimental group saw a clip that emphasized only healthy foods, but the control group viewed a clip that emphasized unhealthy foods. After those clips, children in both groups chose between healthy and unhealthy snacks as a reward for participating.

Initially, Folkvord et al reported positive results:

“These findings indicated a priming effect of the foods the children were exposed to, showing that nutrition education guided by reactivity theory can be promising.”

The Catch

Unfortunately this initial analysis didn’t hold up under a closer look. The problem was that these children were randomized in clusters (i.e., by classrooms). But the initial analysis didn’t account for that. To their credit, the researchers readily shared their data. This permitted a team of researchers at the Indiana University School of Public Health to conduct a re-analysis. Even better, the original authors collaborated with them on that reanalysis.

As a result, the initial finding was reversed and a corrigendum has been published with the following conclusion:

“These findings do not directly indicate a priming effect of the foods children were exposed to. The current study did not show that cooking programs affect food choices of children, although other studies showed that cooking programs could be an effective method in combination with other methods to improve children’s dietary intake.”

Beliefs and Facts

People bring strong beliefs to the subjects of nutrition, obesity, and public policy. That’s normal and good. But it’s even better when they can also bring objectivity and curiosity to test those beliefs and distinguish between myths, beliefs, and facts.

Science is a big help for doing this.

Click here for the study, here for the reanalysis, and here for the corrigendum. For further perspective, click here.

Faithful Servants, painting by Edward Wadsworth / WikiArt

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February 18, 2023