Many people struggling with fatigue, weight gain, brain fog, or low libido may actually be dealing with thyroid dysfunction — and not even know it.

In this episode of Healthy AF, Zane explains how common lifestyle habits like low-carb dieting, intermittent fasting, overtraining, chronic stress, and sleep deprivation can quietly disrupt thyroid function and slow your metabolism.

You'll learn why markers like T3, reverse T3, and TSH matter more than most standard lab panels suggest, how the body adapts to low energy availability, and why many people with thyroid symptoms are often told their labs look "normal."

Zane also breaks down the role of insulin, leptin, liver glycogen, and carbohydrate intake in thyroid hormone conversion — and why reintroducing the right foods can often restore metabolic function.

If you've ever struggled with low energy, stubborn weight gain, cold intolerance, or declining performance despite dieting and training harder, this episode will help you understand what may really be happening inside your metabolism.

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Supportive research

Low carb diet increases incidence of REDs and low T3⁠ https://pubmed.ncbi.nlm.nih.gov/40639795/%E2%81%A0 ⁠ Low carb diet reduces T3 in athletes⁠ https://blogs.bmj.com/bjsm/2023/08/14/a-bad-situation-made-worse-low-carbohydrate-intake-amplifies-low-energy-availability-hormonal-disturbances/⁠ ⁠ Low carb diet induces low thyroid function⁠ https://pmc.ncbi.nlm.nih.gov/articles/PMC11558958/⁠ ⁠ Keto diet reduces thyroid function⁠ https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0269440⁠

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00:00 – Introduction: Thyroid Health and Metabolism 00:40 – Remembering Charlie 02:00 – Common Symptoms of Low Thyroid 03:30 – How Thyroid Affects Metabolism and Energy 04:30 – Hormonal and Cardiovascular Effects of Thyroid Dysfunction 05:30 – Why Thyroid Issues Often Go Undiagnosed 06:30 – Stress, Overtraining, and Aggressive Dieting 08:00 – How Thyroid Hormones Work (T4, T3, Reverse T3) 09:40 – What Low-Carb Diets Do to Thyroid Function 11:00 – Low Energy Availability in Athletes 12:30 – Why Your Body Interprets Low Carb as Scarcity 14:00 – The Impact of Fasting on Thyroid Hormones 15:30 – Liver Glycogen and Overnight Stress Hormones 17:00 – Why High Performers Are Vulnerable 18:30 – Insulin, Leptin, and Thyroid Signaling 20:00 – Optimal Thyroid Lab Ranges Explained 22:30 – Why Symptoms Matter More Than "Normal" Lab Ranges 24:30 – How Thyroid Issues Affect Testosterone in Men 26:00 – Insulin Signaling and Thyroid Conversion 28:00 – Low Carb vs Insulin Resistance: Different Labs, Same Symptoms 31:00 – Why Leptin Is the Missing Link 33:00 – Reintroducing Carbs to Restore Thyroid Function 35:00 – LDL Changes After Increasing Carbohydrates 36:30 – Body Temperature and Metabolic Rate 37:30 – Training, Recovery, and Sleep 38:30 – Best Carbohydrate Sources for Thyroid Health 41:00 – How Much Carbohydrate You Actually Need 43:00 – Macro Ratios for Fat Loss vs Performance 45:00 – What Indigenous Diets Teach Us About Metabolic Health 47:00 – How Ultra-Processed Foods Disrupt Energy Production 49:00 – The Real Cause of Fat Gain and Metabolic Dysfunction 51:00 – Why "Calories In Calories Out" Misses the Real Problem 53:00 – Fixing Metabolism Through Food Quality and Energy Availability