Obesity: My Model’s Better Than Your Model

High Street Model ShipsAll models are wrong, but some are useful. Quite a distinguished collection of obesity researchers are working hard to prove that these words of a great statistician – George Box – were precisely correct. One group, led by David Ludwig, suggests that their carbohydrate-insulin model (CIM) for obesity “better reflects knowledge on the biology of body weight control than the EBM.”

EBM is shorthand for the energy balance model – an old standby often reduced to absurd simplicity. At its simplest, it asserts obesity is merely the result of consuming too much energy while expending too little.

So another group of smart researchers, led by Kevin Hall, took up the challenge. They argue that the energy balance model can be a more robust theory of obesity. In fact, they write that the CIM is really only a “special case” of the EBM

Thus, the debate rages on.

Four New Letters

In AJCN, we have three new letters to critique the defense of the EBM by Hall et al. Two are from authors of the Ludwig paper. Gary Taubes – a journalist for most of his career – writes in the most plain and derisive language:

“If the perspective piece by Hall et al. is indicative of what is considered progress in obesity research, I am not hopeful for the future.”

Another co-author, Mark Friedman, argues that Hall et al “remove ‘balance’ from the EBM” and leave us with a model for obesity driven by the food environment and thus “an energy intake model.” But he argues that evidence is lacking to support their suppositions about the food environment.

The third letter comes from authors of a separate work that Hall et al cited. Vicente Torres-Carot and colleagues believe that obesity is neither an energy problem nor an energy balance problem. They write that Hall et al have misrepresented their work.

Finally, Hall et al defend their formulation of the EBM as a modern understanding of the active endocrine organ that fat tissue is. But they state clearly the need for much more work for a full understanding:

“Future work will elucidate the neuroscience of how the brain’s control of energy intake is influenced by the food environment in the context of the body’s overall energy homeostasis.”

Models Can Be Wrong and Useful

So we must return to George Box telling us that all models are wrong. Surely, these competing models for obesity fit with that idea. All of these folks, arguing passionately for their frameworks, have it wrong. That’s why these are called models. They are only approximations.

But they all offer insights. Perhaps the arguments are part of the process for getting to better insights. A little more humility would make it easier to take, though. Too many people claim they have the answer, when in fact no single answer can satisfy our issues with obesity. One size does not fit all.

Click here and here for the publications that started this debate. For the latest series of letters, click here, here, here, and here.

High Street Model Ships, illustration by Eric Ravilious / WikiArt

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June 19, 2022

One Response to “Obesity: My Model’s Better Than Your Model”

  1. June 19, 2022 at 10:39 am, Allen Browne said:

    Our brains crave simplicity. Biology and physiology are not simple.

    Happy Father’s Day!!