EP 1386
1386. Here’s Why You Still Feel Like Sh*t After Doing Everything Right…
In this episode of The Human Upgrade, Host Dave Asprey sits down with McCall McPherson, physician associate, TEDx speaker, and founder of Modern Thyroid Clinic, to expose one of the most widespread and mismanaged health crises hiding in plain sight. Most doctors test a single thyroid marker, prescribe a medication that only works for a fraction of patients, and send you home. Dave and McCall break down exactly why that approach is failing millions of people, covering how the TSH, T4, T3, and reverse T3 pathway actually works, why T4-only medications like Synthroid leave your cells starving for the active hormone, and how fluoride in tap water, bromine in American wheat, mold exposure, and common inflammatory foods are quietly destroying thyroid function at the root. They also get into why low thyroid is the number one driver of tanked testosterone in both men and women, how Hashimoto’s connects to broader autoimmune risk, and why kids are being put on ADHD medication when the real problem is undiagnosed hypothyroidism.
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In this Episode of The Human Upgrade™...
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.
This is essential listening for anyone serious about biohacking, human performance, anti-aging, functional medicine, supplements, sleep optimization, and using smarter not harder strategies to take control of your biology.
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
Keywords: McCall McPherson, Modern Thyroid Clinic, thyroid testing wrong, full thyroid panel, free T3, reverse T3, Synthroid failure, T3 vs T4, Hashimoto’s remission, fluoride suppresses thyroid, thyroid low testosterone, thyroid ADHD, thyroid depression, hypothyroidism misdiagnosis, thyroid and metabolism, thyroid hair loss, functional medicine thyroid
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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"If someone hadn't helped me, I would be on disability by now. I really believe that."
McCall McPherson
00:00 – Trailer
Dave and McCall preview why most thyroid testing is dangerously incomplete and what it costs you.
01:05 – Intro & Guest Background
McCall McPherson’s credentials, the founding of Modern Thyroid Clinic, and why thyroid became her life’s work.
02:26 – Dave & McCall’s Thyroid Stories
Both host and guest were dismissed by conventional doctors in their late 20s despite being nearly undetectable on thyroid labs.
05:26 – How Thyroid Hormones Work
A clear breakdown of the TSH, T4, T3, and reverse T3 pathway and where the whole system can quietly break down.
12:51 – Why T4-Only Meds Fall Short
Synthroid and levothyroxine are crude oil, not gasoline. If your body can’t convert T4 to T3, the medication is doing almost nothing.
23:05 – Why Thyroid Dysfunction Is So Common
Stress, inflammation, nutrient depletion, overexercise, and environmental toxins are all conspiring to wreck your thyroid.
23:59 – Fluoride, Bromine & Environmental Triggers
Fluoride in tap water and bromine in American wheat directly suppress thyroid function, and this has been documented since 1945.
26:39 – Thyroid & Low Testosterone
Low T3 is the first hormone dysfunction to appear in hypothyroidism, and 99.5 percent of McCall’s patients come in with testosterone below detectable levels.
27:31 – Optimal Lab Ranges for TSH, T4 & T3
The specific numbers you want to see on your labs, and why the ranges printed on your lab report are based on sick people.
36:58 – Mold, Hashimoto’s & Autoimmunity
Mold exposure is one of the top triggers for autoimmune thyroiditis, and Dave shares how toxic mold shaped his own health trajectory.
44:44 – Thyroid, ADHD & Mental Performance
Kids and adults are being medicated for focus and mood disorders when the real issue is undiagnosed hypothyroidism.
49:38 – Supplements for Thyroid Support
Selenium, zinc, magnesium, ashwagandha, and tyrosine all play direct roles in thyroid hormone production and conversion.
51:52 – Vitamin D & Circadian Rhythms
Nearly everyone is vitamin D deficient, circadian disruption suppresses T3 activation, and both are flying under the radar.
56:30 – T3 Safety Myths & Medical Misinformation
Doctors are trained to fear T3, but the research shows higher T3 levels actually decrease cardiovascular events and mortality.
1:00:16 – Key Takeaways & Where to Get Help
Get your full thyroid panel, stop accepting T4-only treatment, and find out how to work with Modern Thyroid Clinic from anywhere in the country.
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