The Randle Cycle: A Physiology-Based Explanation of Fuel Competition and Energy Efficiency

Episode 5 – The Randle Cycle: A Physiology-Based Explanation of Fuel Competition and Energy Efficiency

Why do so many people feel better when they reintroduce carbohydrates — yet can’t explain why?

In this episode of Metabolic Mindset, I break down the Randle Cycle, a core concept in metabolic physiology that explains how fat, protein, and carbohydrates compete for oxidation at the cellular level. You’ll learn why high fat intake can block glucose use, why excess protein without carbohydrates can leave you exhausted, and why carbohydrates are essential for efficient energy production.

We’ll walk through the biochemistry of glucose and fatty acid oxidation, the role of pyruvate dehydrogenase (PDH), and how chronic low-carb, high-fat, or high-protein diets can push the body into a stress-adapted, inefficient metabolic state. I also explain how inadequate carbohydrate intake impacts thyroid function, cortisol, blood sugar stability, exercise performance, and overall energy availability.

This episode is not about eliminating macronutrients — it’s about restoring fuel hierarchy, metabolic efficiency, and flexibility. If you’ve ever felt tired, cold, flat in workouts, or “carb intolerant,” this episode explains what’s actually happening physiologically — and why eating carbohydrates often fixes it.