Implicit Bias: “Just Be More Active to Overcome Obesity”

A fascinating new study is prompting some very clickable headlines this week. It is all about the interaction of genetic risk for obesity and physical activity. It shows that in people with higher genetic risk scores for obesity, the association between physical activity (using daily step counts as a surrogate) and BMI is different than it is for people with lower genetic risk scores. The clickbait headlines from this study tell people that if they have a genetic risk for obesity, they simply have to be more active to overcome it. In the words of lead author Evan Brittain:

“Most importantly, I would like for patients to know that your genetic risk doesn’t determine your overall risk of obesity, and you can actually overcome that risk by being more active.”

A Different Relationship with Physical Activity

It’s no surprise that higher levels of physical activity are associated with less risk of obesity. The new finding here is that the relationship is different in people with high genetic risk scores. At any given level of physical activity, these people are more likely to have obesity. It makes sense, when you think about it.

But remember that this is an observational study. Not an intervention study. So all the claims about overcoming obesity by being more active simply are not supported by this study. That’s because this research did not test what happens when people with a high genetic risk score take up the challenge to “be more active.”

A Sneaky Expression of Bias

This statement sounds innocent enough. One might think it’s just encouragement to lead an active life. But for a person living with obesity because of genetic risk that they did not choose for themselves, it is an implicit indictment.

Ximena Ramos Salas, who chairs Bias180, describes the problem:

“The implicit message is that people with obesity just need to take a given number of steps every day and they won’t get obesity. It is paternalistic and feeds into the individual responsibility for obesity narrative. That narrative is the fundamental driver of weight bias, stigma, and discrimination. Would we say this to a person with cancer?”

This is interesting research. But interpreting it to mean that people with a genetic obesity risk should be held to a higher standard for physical activity is a mistake. First, because it promotes bias and second, because the research did not demonstrate this.

Click here for the research and here for the press release from Vanderbilt. For more on implicit bias, click here and here.

Active Volcano at Fimmvörðuháls in 2010, photograph by Boaworm, licensed under CC BY 3.0

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March 29, 2024