EB. 139: The Truth About the Randle Cycle: Why You Can Eat Carbs and Fats Together

Nov 25, 2025

Mike Vabe, a health and bioenergetics expert, delves into the complexities of the Randle Cycle, dispelling myths about carbohydrate and fat consumption. He explains how this cycle impacts fuel usage, suggesting that eating these macronutrients together doesn't necessarily lead to weight gain or insulin resistance. The discussion covers the efficiency of using fats versus carbohydrates as fuel, how stress affects mitochondrial function, and the importance of the right balance of these nutrients in our diet for optimal health.

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INSIGHT

Randle Cycle Is A Cellular Fuel Switch

The Randle cycle describes fuel competition at the single-cell level where using one fuel suppresses others.
It explains mechanisms, not on/off dietary rules, and is most relevant to cellular physiology and disease states.

INSIGHT

Fat Oxidation Backlogs The Electron Chain

Fat beta-oxidation produces a higher FADH2-to-NADH ratio which overloads coenzyme Q in the electron transport chain.
This backlog increases mitochondrial ROS and lowers the NAD+ to NADH ratio, impairing energy flow.

INSIGHT

Fat Metabolism Brakes Carbohydrate Oxidation

A high NADH/NAD+ ratio from fat metabolism slows the citric acid cycle and inhibits PDH, blocking pyruvate entry.
Buildup of citrate and acetyl‑CoA further suppresses glycolysis via PFK and hexokinase effects.

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In this episode we discuss:

How the Randle Cycle actually works
Whether eating carbs and fats in the same meal causes weight gain and insulin resistance
The efficiency of using fats as a fuel vs carbohydrate
How stress impacts fuel usage in the mitochondria
How to determine the optimal amount of carbs and fats in your diet

Check out the Energy Balance Solution program here: https://www.jayfeldmanwellness.com/solution/

Click here to check out the show notes:
https://www.jayfeldmanwellness.com/eb-139-the-truth-about-the-randle-cycle-why-you-can-eat-carbs-and-fats-together/

Timestamps:

0:00 – intro

0:53 – misconceptions regarding the Randle cycle in the alternative health world

4:57 – what is the Randle cycle?

7:06 – what most people get wrong about the Randle cycle

10:44 – fat oxidation leads to increased ROS production and a decreased NAD+/NADH ratio

16:29 – how fat oxidation inhibits the utilization of carbohydrates

21:03 – the Randle cycle shows the benefits of burning carbs for energy

25:56 – how fat oxidation inhibits the utilization of carbohydrates cont’d

26:57 – metabolic dysfunction, not glucose, drives insulin resistance and aging

32:07 – fat metabolism causes a buildup of citrate which reduces glucose uptake and utilization

38:39 – how glucose oxidation inhibits the uptake and utilization of fats

45:32 – whether you can “activate” or “deactivate” the Randle cycle

47:22 – glucose oxidation leads to an optimal NAD+/NADH ratio and decreased ROS production

52:08 – the protective effects of CO2 and why the brain can’t use fats as a fuel

53:17 – whether we should strive for metabolic flexibility

55:55 – fat metabolism and ketone production as a mechanism for energy conservation and glucose sparing

1:00:02 – insulin resistance as a state of excess fat metabolism and decreasing fat metabolism or stress hormones improves this state

1:05:28 – should we avoid eating carbs and fats together due to the Randle cycle?

1:08:08 – different cells, tissues, and organs can use different fuels at the same time