Your thyroid controls your energy, your metabolism, your testosterone, your mood, and your ability to think clearly. Most doctors are testing it wrong and treating it wrong, and this episode tells you exactly what to do instead.
Host Dave Asprey sits down with McCall McPherson, a physician associate, TEDx speaker, and founder of Modern Thyroid Clinic, Modern Weight Loss, and the advocacy platform Thyroid Nation. McPherson has been honored on the 2024 and 2025 Inc. 5000 lists and named a 2025 Top 500 Inc. Female Founder. She hosts the Modern Thyroid and Wellness podcast and built her entire practice around thyroid care after being failed by conventional medicine while managing her own hypothyroidism. She treats patients nationwide via telemedicine and has become one of the most trusted voices in functional medicine thyroid care.
Dave and McCall expose why standard TSH-only testing catches just 1 to 2 percent of actual thyroid variation, why the medication most doctors prescribe (Synthroid/levothyroxine) fails a massive percentage of patients, and why T3 is the active hormone that mainstream medicine has been trained to fear without good reason. They also get into how fluoride in tap water, bromine in American wheat, mold exposure, dairy, gluten, and oxalates directly suppress thyroid function and drive autoimmunity. If you want to optimize your metabolism, protect your mitochondria, support brain optimization, and stop leaving your longevity on the table, thyroid is the first domino.
You’ll Learn:
-Why testing TSH alone misses thyroid dysfunction in the vast majority of people
-What a full thyroid panel actually includes and the optimal ranges for T4, T3, and reverse T3
-Why T4-only medications like Synthroid fail and what works better
-How low thyroid directly tanks testosterone and libido in both men and women
-The environmental triggers destroying your thyroid, including fluoride, bromine, mold, and inflammatory foods
-How Hashimoto’s connects to broader autoimmune risk and what drives it into remission
-Why kids are being misdiagnosed with ADHD when the real issue is hypothyroidism
-The supplements and cofactors (selenium, zinc, magnesium, ashwagandha, tyrosine) that support thyroid activation
-How thyroid optimization connects to metabolism, dementia prevention, cardiovascular health, and economic outcomes
-When to use T3 only vs. a T3/T4 combination, and how to know if your dose is off
Resources:
• Learn More About McCall’s Work At: https://www.modernthyroidclinic.com/
• Get McCall’s Thyroid Guide: https://gift.modernthyroidclinic.com/
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Timestamps:
00:00 – Trailer
01:05 – Intro & Guest Background
02:26 – Dave & McCall’s Thyroid Stories
05:26 – How Thyroid Hormones Work
12:51 – Why T4-Only Meds Fall Short
23:05 – Why Thyroid Dysfunction Is So Common
26:39 – Thyroid & Low Testosterone
27:31 – Optimal Lab Ranges for TSH, T4 & T3
36:58 – Mold, Hashimoto’s & Autoimmunity
44:44 – Thyroid, ADHD & Mental Performance
49:38 – Supplements for Thyroid Support
51:52 – Vitamin D & Circadian Rhythms
56:30 – T3 Safety Myths & Medical Misinformation
1:00:16 – Key Takeaways & Where to Get Help
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