What Explains Racial and Ethnic Disparities in Obesity?

What could it be that explains racial and ethnic disparities in obesity? The most common thought is that it’s all about differences in health behaviors, along with social and economic status. The thinking is that poverty and educational disadvantages make it hard to eat healthy and stay fit. But a new study in Obesity tells us this may be utterly false. In fact, researchers led by Adolfo Cuevas found no evidence to support that presumption.

They found that the effects of stress might explain some of the disparities – especially in Hispanic populations. Even so, the stressors they studied could explain no more than 14 percent of these disparities.

An Oaxaca-Blinder Analysis

Cuevas et al used a technique known as an Oaxaca-Blinder decomposition analysis to sort out these factors. Their goal was to tease out the relative contributions of stress, status, and health behaviors to obesity disparities. They used data from the Chicago Community Adult Health Study.

The health behaviors in the study included fruit and vegetable consumption. Also the frequency, intensity, and duration of physical activity. For social and economic status, they used income, education, and employment. Measures of psychosocial stress included childhood adversity, acute life events, financial strain, neighborhood stressors, employment stressors, and experiences of discrimination.

At the end of all of their analysis, they could find nothing to support some common assumptions. The data provided no hints that poverty and poor education cause disparities in obesity. Nor could differences in diet and exercise explain them.

Once Again, Intuitive Thinking Fails

This is just one more example of the many ways that obesity mocks our assumptions. Will educating disadvantaged communities to eat more fruits and vegetables do anything to reduce disparities in obesity? Probably not. It feels good. It’s a good idea for all kinds of people. But it’s not likely to reduce disparities in obesity.

Stress is clearly a factor. But it’s far from the whole story in racial and ethnic disparities. Much is unknown. Other factors are well-known, though. For example, we know quite well that obesity is a highly heritable condition. We also know that genetic ancestry plays a role in the susceptibility of African American and Hispanic individuals. Also, being born in the U.S. adds to that susceptibility. These observations come from recent research on the BioMe Biobank.

Racial and ethnic disparities in obesity are a fact. However, our understanding of what explains that fact is clearly incomplete. It’s probably not behavioral differences. Maybe not even income or education. Differences in physiology matter and that’s why obesity is so highly heritable. The environment that triggers obesity also matters greatly.

To understand all of this, and ultimately reduce these disparities, we need more curiosity and more objectivity. Our assumptions don’t serve us well.

Click here for the study from Cuevas et al and here for the study from the BioMe Biobank.

Light Handed, photograph © Vox Efx / flickr

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January 8, 2020