The Enduring Fascination with Causal Pathways for Obesity

A new paper this week reminds us of the enduring fascination with causal pathways for obesity. Why has the prevalence grown so relentlessly? How can we reverse it? This preoccupation has been the source of controversy and mistakes in dealing with obesity. One of the more memorable controversies is the back-and-forth debates between David Ludwig and Kevin Hall about the merits of the carbohydrate-insulin model (CIM) versus the energy balance model (EBM) for obesity pathogenesis.

This week in Nature Metabolism, we are enjoying the rare treat of an analysis for which both Ludwig and Hall are authors. This paper demonstrates that when people with diverse views collaborate, good insights can come forth. Its authors, which include quite a few luminaries in the field of nutrition and obesity research, make three points that stand out as especially valuable.

Maybe One Model Can’t Give All the Answers

First, they point to the mistake of expecting too much of a single model:

“While testing the components and proposed pathways of the EBM and the CIM is necessary, it might not be sufficient to understand the obesity epidemic, which could also be rooted in sociocultural factors. Different mechanisms could lead to obesity in different individuals, operate at different stages of the natural course of the disorder, and contribute to the slow progression and persistence of this phenotype.”

Perhaps the arguments about EBM versus CIM are merely perpetuating a false dichotomy.

Knowing the Cause(s) Does Not Solve the Problem

Second, in such a problem like obesity, which springs from complex, adaptive systems, even knowing all the causes of obesity will likely be insufficient for resolving it:

“Knowing the cause of a disease does not necessarily mean that removing that cause will treat the disease; although, it should certainly help prevent it.”

For people living with obesity – which is approaching half the U.S. population – the excessive preoccupation with the “root cause” of obesity is annoying. Because it serves to push consideration of our medical needs into obscurity.

Thinking More Broadly

And finally, there is the persistent false assumption that it’s all about the food. In their concluding words, the authors make a plea to think more broadly about the problem.

“Looking beyond the food environment is also necessary to discover external factors that may have been undervalued or even overlooked.”

You will find a lot of wisdom about obesity and nutrition research in this paper. We suggest a careful reading.

Click here for this new paper by Faidon Magkos and colleagues. For further perspective, click here, here, and here.

Travelers on a Mountain Path at Night, painting by Hiroshige / WikiArt

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August 23, 2024