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.

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Work with me at Nourish: https://www.usenourish.com/providers/shara-perry?referralSource=Nourish+dietitian&referralName=Shara+Perry&utm_source=Nourish_dietitian&utm_term=Shara_Perry

In this episode of Metabolic Mindset, we go beyond calories and macros and dive deep into the physiology of chronic dieting and metabolic adaptation. You’ll learn exactly how prolonged calorie restriction alters thyroid function, leptin signaling, cortisol output, mitochondrial efficiency, muscle metabolism, and fat tissue behavior — and why these adaptations make fat loss increasingly difficult over time. This episode explains, at a cellular and hormonal level, why long-term dieting backfires and what your body is actually responding to when fat loss stalls despite “doing everything right.”

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Work with me at Nourish: https://www.usenourish.com/providers/shara-perry?referralSource=Nourish+dietitian&referralName=Shara+Perry&utm_source=Nourish_dietitian&utm_term=Shara_Perry

In this episode, we break down why fat loss can stall even when calories are controlled and workouts are consistent. You’ll learn how cortisol, thyroid signaling, fuel availability, and recovery determine whether your body burns fat or holds onto it—and why eating less is often not the answer.

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Work with me at Nourish: https://www.usenourish.com/providers/shara-perry?referralSource=Nourish+dietitian&referralName=Shara+Perry&utm_source=Nourish_dietitian&utm_term=Shara_Perry

In this episode of Metabolic Mindset, I break down how to calculate calories and macros using a pro-metabolic framework. You’ll learn how to estimate true maintenance calories, adjust intake for fat loss, maintenance, or muscle gain, and set macros in a way that supports energy, hormone health, and metabolic resilience. I cover why protein anchors the system, carbs fuel the metabolism, fats stay moderate, and how carb tolerance expands as your metabolism heals.

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Work with me at Nourish: https://www.usenourish.com/providers/shara-perry?referralSource=Nourish+dietitian&referralName=Shara+Perry&utm_source=Nourish_dietitian&utm_term=Shara_Perry

What is a pro-metabolic diet, really?
In this episode, Shara breaks down the physiology behind metabolism, why so many mainstream nutrition messages backfire (like “eat less, move more” and “carbs slow your metabolism”), and what it actually means to support the thyroid and mitochondria. You’ll learn the core principles of a pro-metabolic approach, why carbs and minerals matter, and how to start fueling your body without extremes.

Support the show

Work with me at Nourish: https://www.usenourish.com/providers/shara-perry?referralSource=Nourish+dietitian&referralName=Shara+Perry&utm_source=Nourish_dietitian&utm_term=Shara_Perry