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Introduction
The pathogenesis of obesity is clearly complex. And the need to have a comprehensive model to explain this pathogenesis is important.
One such model, termed the Energy Balance Model, has largely been the consensus paradigm of obesity scientists to this point. Specifically, a recently published paper in the American Journal of Clinical Nutrition by Dr. Kevin Hall and his colleagues outlined the various nuances of the model, as well as common misconceptions about the model.
However, there are others who propose that this is not the correct model of obesity, but rather that obesity pathogenesis can be better explained by a model called the Carbohydrate-Insulin Model (CIM) of obesity.
While this model has been proposed in various forms over the past couple of decades, the most recently published revision/update of this model was that put forward by Dr. David Ludwig and colleagues, in a Perspective published, also in the AJCN, in December of 2021.
In this episode, Dr. Kevin Hall (lead author of the paper mentioned above) and Dr. Stephan Guyenet are on the podcast to discuss the debate surrounding these two models. Specifically, the discussion will focus in on the Hall et al. (2022) and Ludwig et al. (2021) papers, as well as previous work leading up to both.
Related resources
- Hall et al., 2022 – The energy balance model of obesity: beyond calories in, calories out
- Ludwig et al., 2021 – The carbohydrate-insulin model: a physiological perspective on the obesity pandemic
- Drewnowski et al., 2022 – Misleading or factually incorrect statements in the American Journal of Clinical Nutrition Perspectives article by Ludwig et al
- Ludwig & Ebbeling, 2018 – The Carbohydrate-Insulin Model of Obesity: Beyond “Calories In, Calories Out”
- Speakman & Hall, 2021 – Carbohydrates, insulin, and obesity
- Ludwig & Sorenen, 2022 – An integrated model of obesity pathogenesis that revisits causal direction
- Schwartz et al., 2000 – Central nervous system control of food intake
- Twitter:
- Episode 376: Kevin Hall, PhD – Plant-based Diet vs. Ketogenic Diet: Impact on Calorie Intake
- Episode 165: Kevin Hall, PhD – Testing the Carbohydrate-Insulin Model & a Response to Gary Taubes
- Episode 88: Kevin Hall, PhD – The Physiology of Fat Loss, Weight Regain & Carb or Fat Restriction?
- Episode 307: Stephan Guyenet, PhD – Are Popular Nutrition & Health Books Trustworthy, Accurate & Health-Promoting?
- Episode #200: Saturated Fat Panel Discussion
- Episode 68: Stephan Guyenet, PhD – Overeating, Fat Mass Regulation & Energy Homeostasis
- StephanGuyenet.com
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- [06:19]What is a valid model?
- [18:52]Energy Balance Model as a model of obesity vs. energy balance as a law of physics
- [30:30]Body fat set point
- [44:09]Criticisms of the EBM: Are palatability and processing important?
- [52:49]Deep dive on more predictions of the Carbohydrate Insulin Model
- [1:38:04]Closing statements
The Hosts
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Kevin Hall is a research scientist at the NIH. Specifically, he is Senior Chief of the Integrative Physiology Section of the Laboratory of Biological Modeling at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
His laboratory investigates how metabolism and the brain adapt in response to a variety of interventions to diet and physical activity. They carry out studies to better understand the complex mechanisms regulating macronutrient metabolism, body composition, and energy expenditure.
Stephan Guyenet spent 12 years in academia studying neurodegenerative disease and obesity neuroscience. He was a postdoctoral fellow at the Univeristy of Washington, studying the neuroscience of obesity and eating behavior. Previous to that he completed a PhD in neuroscience.
Stephan is the author of the popular and well-received book ‘The Hungry Brain‘, which lays out the science behind the brain’s role in obesity.
Key Ideas
Danny’s Key Ideas in this Episode:
- Primary differences between the models: Direction of causality
- The energy balance model has much more convincing evidence as a model of obesity
1: Primary differences between the models: Direction of causality
The Energy Balance Model of obesity (EBM) suggests that the primary player here is the brain. And specifically, regulation of body mass is controlled by the brain. This is below our conscious awareness. So the set of processes that the brain is orchestrating, that in turn controls our food intake, occurs in response to both our energy demands and the food environment. So external factors can impact the various internal signals and hormones that impact our food intake. And the brain is the master controller here.
