Elegant Explanations for Obesity Causes? Fuhgeddaboudit

John Keats seems to be guiding a great many people trying to make sense of the stubborn rise in obesity. His advice that beauty is truth has surprising power. So we look for elegant solutions to all challenges. David Ludwig has an elegant explanation for the cause of excess obesity in the carbohydrate insulin model. But the debates persist about this and many other tidy explanations for our dilemma with obesity. In part two of a collection of articles arising from a discussion meeting on the causes of obesity, Roger Zoh and colleagues suggest that this quest for an elegant explanation is misguided:

“Perhaps it is time for us to stop thinking about the singular cause of obesity or the factor that led to the obesity pandemic, or the principal factor, and instead to be willing to embrace inelegant causal models that require the integration and conglomeration of multiple other factors.”

It’s the Carbs!

In his contribution to the commentary from that same meeting, Ludwig says he has the answer that has been so elusive:

“A diet high in rapidly digestible carbohydrates raises the insulin-to-glucagon ratio, shifting energy partitioning towards storage in adipose, leaving fewer calories for metabolically active and fuel sensing tissues. Consequently, hunger increases, and metabolic rate slows in the body’s attempt to conserve energy. A small shift in substrate partitioning though this mechanism could account for the slow but progressive weight gain characteristic of common forms of obesity.”

Stuck on 18th-Century Homeostasis and Beautiful Elegance

In the publications from this meeting we also have an excellent account of historical thinking about energy regulation in the human body. It goes back to Lavoisier and the 18th century. Nori Geary explains that, even after centuries of work, we have only begun to understand its mechanisms. John Speakman and Kevin Hall conclude that we sorely need to test the diverse models that try to explain the causal pathways for obesity.

Yet the public remains stuck on simple explanations of “calories in and calories out.” Sages endorse them in respected publications. Zoh et al tell us why:

“The appeal of parsimony has led many to search for elegant and simple theories, which are often perceived as beautiful. Beauty has its own value. Yet, as Strevens and others have pointed out, there is no logical reason that a theory must be beautiful or why a more beautiful or parsimonious theory is necessarily the correct one.”

Elegant explanations for the causes of obesity are seductive distractions. The truth of obesity is more complex than these pretty little lies can explain.

Click here for the paper by Zoh et al.

Elegance, painting by Samuel Peploe / WikiArt

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September 11, 2023