Saturday, October 16, 2021
Mitochondrial Health

Ep. 47: A Critique of The ROS Theory of Obesity (The Croissant Diet Part 1)

Show Notes:
Free Energy Balance Mini-Course:

In this episode we discuss:
-The major issues with the ROS theory of obesity
-Why fat-burning is inefficient and doesn’t lead to healthy fat loss
-The real problem with PUFA (and why they don’t decrease ROS production)
-Why carbohydrates and insulin don’t cause fat gain
-How increasing cellular energy through efficient mitochondrial respiration is the key to healthy fat loss

0:00 – intro
3:26 – an introduction to The Croissant Diet and Fire In A Bottle
10:04 – an introduction to ROS and the varying ROS-producing effects of fats and carbs
16:10 – the ROS theory of obesity, Randle cycle confusion, and how fat-burning causes physiological insulin resistance
25:30 – the effect of fatty acid saturation on ROS production when oxidized in mitochondria
29:36 – the real problem with PUFA and why they lead to increases in ROS production rather than decreases
42:28 – why the inefficient mitochondrial respiration that’s fueled by fatty acid oxidation and produces excessive amounts of ROS harms our health
47:39 – the problems with the idea of hormesis
58:39 – why fat-burning doesn’t increase fat loss
1:05:45 – anti-hormesis and the bioenergetic view of obesity

​​To see the studies and articles referenced throughout this episode, check out the show notes at


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4 thoughts on “Ep. 47: A Critique of The ROS Theory of Obesity (The Croissant Diet Part 1)
  1. Wow that was a great discussion of physiology.

    I know of the "Trim Healthy Mama" diet, which is based on the idea that our bodies cannot burn fat and carbohydrates at the same time. On the level of individual mitochondria, this may be true. However, you make it clear that body as a whole (which obviously has millions of mitochondria) can burn both fuels simultaneously. Also, It was interesting to learn that polyunsaturated fats produce less ROS that saturated fats when they are burned (theoretically) in the cell. It is good that you clarified that polyunsaturated fats are unlikely to ever be burned in the cell, considering their fragile state when exposed to cooking, body temperature, etc.

  2. Hi Jay, thank you so much for clarifying the ideas behind the ROS theory since it was pretty confusing at first glance!

    By the way, do you know where I can find the study (or data) where pigs are fattened up by PUFA, which Ray Peat refers in his article? It seems that I can't find it anywhere despite the effort.

    Also, although you may be already aware of it, I recently stumbled upon some personally interesting studies in pigs that imply the importance of proper energy production.


    The first study pretty much backs up almost everything you and Mike have been discussing throughout the show, and the second one mentions the enhanced growth of villus height compared to the control , which implies the enhancement of cell differentiation the the body as opposed to uncontrollable cell division.

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