EB. 135: Eric Westman Debate Follow-Up: The Research on Low-Carb Vs High-Carb Diets

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Sep 11, 2025

Explore the fascinating effects of low-carb diets on mitochondrial function and energy production. Delve into the hormonal impacts of carbohydrate restriction, including how it influences insulin resistance. Discover the confusion surrounding glucose metabolism versus fat oxidation and the implications for health. Uncover new insights from rodent studies and their relevance to human metabolism. The discussion raises questions about the efficiency of fat metabolism and its connection to oxidative stress, inviting listeners to rethink dietary choices.

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INSIGHT

Ketosis Lowers Active Thyroid Hormone

In a four-week ketogenic metabolic-ward study glucagon rose ~40% and T3 fell while TSH and free T4 rose.
The pattern indicates reduced T4→T3 conversion and a lowered thyroid state on keto.

INSIGHT

Athletes On Keto Show Elevated Glucagon

Long-term ketogenic athletes showed higher baseline glucagon and similar cortisol patterns, suggesting coordinated keto-adaptation stress signaling.
Athletic keto-adaptation still relies on stress hormones to drive high fat oxidation.

INSIGHT

Long-Term Low-Carb Diets Elevate Glucagon

A two-year Paleolithic diet study linked lower carbs/higher fat and higher beta-hydroxybutyrate to increased fasting glucagon.
Longer-term carb restriction correlates with sustained glucagon elevation.

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In this episode we discuss:

The mitochondrial effects of low-carb diets, and whether they’re actually worse for energy production
The downstream hormonal effects of low-carb diets
Whether insulin resistance is a problem of excess glucose metabolism or excess fat metabolism
Whether high-carb diets cause overeating and insulin resistance
And much more

Check out the Energy Balance Mini-Course here: https://www.jayfeldmanwellness.com/energy/

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Click here to check out the show notes:
https://www.jayfeldmanwellness.com/eric-westman-debate-follow-up-the-research-on-low-carb-vs-high-carb-diets/

Timestamps:

0:00 – intro

1:05 – why I’m recording this debate follow-up

3:38 – how the body responds to carbohydrate restriction and the broader biological context

9:47 – the mitochondrial effects of low-carb diets: glycolysis vs beta-oxidation, NADH/FADH2 ratios, NAD+/NADH ratios, and effects at the electron transport chain

15:16 – fat oxidation leads to slower rates of ATP production and higher rates of ROS production

18:14 – how fat oxidation blocks glucose utilization, slows mitochondrial respiration, and reduces carbon dioxide production

20:58 – ketone vs. glucose metabolism

21:52 – glucose metabolism confusion, glycolysis, and whether ketones are beneficial

24:25 – the hormonal effects of low-carb diets

28:13 – how do we know that fat metabolism is less efficient than glucose metabolism?

34:09 – whether research on fat metabolism in rodents applies to humans and other animals

37:02 – the research showing that fat oxidation increases ROS production and reduces mitochondrial efficiency in various animals (including humans)

40:31 – the research showing the mechanisms of increased ROS production and reduced efficiency of ATP production with fatty acid metabolism

47:41 – mitochondrial uncoupling increases during fat metabolism due to increases in oxidative stress

49:19 – are there adaptations on a keto diet that would prevent the harmful effects of fat metabolism?

52:48 – are there biopsies done on long-term ketogenic diets showing that fat oxidation doesn’t lead to a decreased NAD+/NADH ratio and more ROS production?

59:17 – whether increased fatty acid oxidation enzymes would reduce ROS production in the mitochondria as Dr. Westman suggested

1:02:58 – low-carb and ketogenic diets in rodents cause increased oxidative stress and less efficient ATP production

1:11:41 – do ketones protect against ROS?

1:16:18 – do the potential positive effects of ketones outweigh the negative effects of ketogenic diets?

1:27:47 –low-carb and ketogenic diets cause oxidative stress and insulin resistance in humans1:36:30 – the evidence that glucagon is a stress hormone

1:39:45 – low-carb and ketogenic diets cause physiological stress in humans

1:43:46 – the effects of low-carb and ketogenic diets on cortisol

1:48:29 – low-carb and ketogenic diets decrease thyroid activity

1:53:54 – effects of low-carb and ketogenic diets on reproductive hormones