Urban Legends of Obesity Prevention

For the last four decades, obesity prevention has been quite a challenge. We’ve heard much talk about bold programs. We’ve seen more than a few victory celebrations. And yet, the prevalence of obesity keeps climbing. So recently, when Tamar Haspel wrote about “jaw-dropping” success in Huntington, WV, she caught our attention. She described a drop from 45 to 33 percent obesity prevalence over ten years. This is the stuff of legends in obesity prevention.

Shouldn’t we all just have more of what Huntington is having?

Objective Progress

It’s definitely worth celebrating when we see progress. If you look at the obesity trends for Cabell County, where Huntington is located, you can see what looks like three years of improvements in obesity prevalence. This is good.

What’s more, many good things are happening to improve the quality of the food environment in Huntington. An emphasis on local, whole foods has found broad support in the community. A farmers’ market, Wild Ramp, is meeting the needs of diverse customers. Schools have taken to preparing better meals on site and providing them to kids year round.

All of these changes are positive developments that the community celebrates.

Knowing What Works

However, seeing good things happen in your community and correlating those with an improvement in obesity prevalence does not add up to proof for how to prevent obesity.

First of all, it’s important to understand a concept called regression to the mean (RTM). This concept is important because when you have a very bad or a very good score on something, it’s bound to change. Even if you do nothing, outliers naturally drift back toward the mean.

Back in 2008, Huntington had the highest obesity rate in the U.S. It had nowhere to go but down. RTM dictates that the obesity rate in Huntington would drift down toward a more average level naturally – even in the absence of any intervention.

Why does this matter? Andrew Brown of the Indiana University School of Public Health explains:

We care why obesity rates decrease because public health practitioners are implementing programs. Those programs have real and opportunity costs. If they are not actually effective, then the continued use of the intervention is using up resources that could be put towards effective solutions. Worse still, the mistaken belief in effectiveness of a program inevitably results in public health practitioners recommending those potentially ineffective approaches to other communities.

Compelling Anecdotes Are Not Enough

Urban legends of obesity prevention can easily and innocently grow out of a compelling anecdote. Huntington, WV, has done some good things. But obesity is a chronic problem that arises from complex systems at work in our communities.

If we want to overcome it, we need to be curious enough to study what works and what doesn’t with scientific rigor.

Click here, here, and here for more on the experience in Huntington, WV.

Legendes, illustration by Raphael Kirchner / WikiArt

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June 29, 2020