BV #23: Keto Raises Stress, Sugar Lowers It (Ray Peat on Fasting & Blood Sugar).

Feb 3, 2026

They debate Ray Peat’s take on fasting and whether 12–15 hour fasts trigger physiological stress. The conversation covers how glycogen, thyroid function, and fuel shifts drive stress hormones and ketosis. They argue carbs and sugar can be anti-stress tools and discuss risks of long-term low carb, PUFA release during fasting, and practical strategies for recovery and reducing metabolic stress.

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INSIGHT

Stress Is An Energy Supply Problem

Stress is fundamentally an energy-supply problem where demand outpaces ATP production.
Jay Feldman explains stress hormones (glucagon, adrenaline, cortisol) mobilize fuel and chronically lower metabolic rate and thyroid function.

ANECDOTE

Panic Attacks From A Starvation Breakfast

Theresa recounts a client with panic attacks who drank black coffee, celery juice, and whiskey and was effectively starving.
The panic stemmed from fuel depletion, showing nervous-system tools can't fix metabolic underfueling.

INSIGHT

Glycogen Depletion Triggers A Hormone Cascade

When liver glycogen is low the body escalates hormone stages from glucagon to adrenaline, and finally cortisol to produce glucose.
Ray Peat (via clips) highlights cortisol activation as the classic harmful stress stage when glycogen runs out.

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In this episode we discuss:

Ray Peat’s ideas about fasting and the stress response
Why relying on fatty acid oxidation is inherently stressful

Free Energy Balance Food Guide: https://jayfeldmanwellness.com/guide

The Nutrition Blueprint: https://mikefave.com/the-nutrition-blueprint/

Theresa's Instagram: https://www.instagram.com/livingrootswellness/

Timestamps:

0:00 – intro

1:03 – Ray Peat’s view on fasting for 12–15 hours without triggering stress

4:22 – the true definition of stress and how much stress is optimal

9:18 – how the efficiency of glucose metabolism and glycogen storage impacts stress

12:23 – whether we agree that fasting for 12–15 hours doesn’t cause stress in healthy people

17:05 – do hunger signals mean the stress response has already started?

21:08 – the short- and long-term costs of low carb diets

22:22 – finding balance between eating frequently to reduce stress and spacing meals out strategically

24:47 – why meditation, magnesium, and other tools don’t stop physiological stress

27:04 – Ray Peat on what happens when stored glucose (glycogen) runs out

28:53 – hypothyroidism as a driver of poor glucose utilization and liver glycogen storage

31:50 – stress hormones and elevated fatty acid metabolism characterize the stress response

34:50 – ketosis mimics starvation and lowers the metabolic rate

36:50 – sugar is anti-stress and whether sugar is addictive

41:46 – once you add in carbs you won’t go back

44:12 – how your body adapts when you add in carbs following low-carb diets

48:30 – Ray Peat on the harmful effects of fasting

50:14 – the cost of stress and increased fat metabolism

52:06 – the dangers of releasing PUFA from storage and how long it takes to deplete PUFA

55:11 – strategies for protecting against PUFA

1:01:50 – how long it takes to see benefits from lowering PUFA and setting expectations for progress

1:06:00 – binge-eating and food addiction resolved with a bioenergetic approach

1:10:48 – how low-carb and keto diets cause intense cravings and food obsession while a bioenergetic approach resolves them