THE Gene That Causes Obesity? Nope!

Every Friday, we get a little bundle of joy in our inbox from the Obesity and Energetics Offerings. It’s a thought-provoking compilation of a week’s worth of new publications related to obesity and biological energy regulation. One feature of it that seldom fails to bring a smile is the Headline vs Study. This week was no exception: A single gene could be responsible for childhood obesity shouts the headline.

Nope. Not even close. The publication this headline was misreporting comes from an excellent body of research that identified a new and rare monogenic cause of severe obesity. The authors discovered an Agouti Signaling Protein (ASIP) in five of 1,746 children with obesity.

But this genetic signaling protein is hardly THE cause of of childhood obesity. It is A cause. And a rare one at that.

So Do Genes Cause Obesity?

This headline versus study skirmish puts a spotlight on a question about obesity that routinely hangs people up. How can it be that a person’s risk of obesity is largely driven by the genes they inherit? Genes can’t possibly be responsible for the “obesity epidemic,” writes one twitterer, because human genetics don’t change as fast as obesity has risen.

This is an expression of the the false dichotomy of nature versus nurture. In the dynamics of a disease driven by genetic susceptibility, both nature and nurture play a role. Genes set the table for obesity. The environment serves it up. We have seen dramatic rises in obesity prevalence because the environment has changed to trigger more obesity in genetically susceptible individuals.

The Misleading Desire to Simplify

Obesity is perhaps a textbook case to illustrate H.L. Mencken’s wisdom about complex problems. “For every complex problem, there is an answer that is clear, simple, and wrong.” We have cycled through enough of these simple answers to make our heads spin. Fat, sugar, salt. Junk food advertising before 9 pm. Soda taxes. Plant-based diets. Ultra-processed food. Personal responsibility, for goodness sake!

All of these righteous answers are seductively simple. So it is with the wish to tell the world that a single gene might be the cause of childhood obesity. But they all falsely simplify a complex problem of human systems.

Click here for the research on ASIP, here, here, and here for more on the genetic basis for obesity. For more insights on the complexity of obesity, click here, here, and here.

Genetic Snips, illustration by David S. Soriano, licensed under CC BY-SA 4.0