43. What 10 Years of Keto Did to My Thyroid, Gut & Metabolism with Dr. Rachel Brown
Mon Jan 19 2026
Low-carb, ketogenic, and carnivore diets have helped a lot of people — myself included — at different stages of their health journey. But what happens when a strategy meant to heal is followed too long without reassessment?
In this episode of Healthy AF, I sit down with Dr. Rachel Brown, a psychiatrist and functional medicine practitioner who shares her deeply personal experience after 10 years of ketogenic eating — six of those strictly carnivore.
Dr. Brown opens up about the symptoms she believes were connected to long-term carbohydrate restriction, with gut dysbiosis and thyroid dysfunction becoming the most prominent issues. Coming from both a psychiatric and functional medicine background, she brings a rare perspective — one that bridges mental health, metabolism, and digestive health.
We explore how restrictive diets can alter the gut microbiome over time, why a lack of fermentable carbohydrates may compromise microbial diversity, and how chronic stress physiology can quietly impact thyroid signaling. Dr. Brown also explains how symptoms can be missed or rationalized in high-discipline health communities, where feeling unwell is often reframed as "adaptation."
This is not an anti-keto or anti-carnivore conversation. It's an anti-dogma conversation.
We talk about the importance of metabolic flexibility, ongoing self-assessment, and the willingness to evolve as your body's needs change. Dr. Brown emphasizes that healing isn't about ideology — it's about listening to physiology, respecting individual variability, and understanding that no approach should be considered permanent by default.
If you've ever wondered whether a diet that once helped you might now be holding you back, this episode offers clarity, nuance, and reassurance that changing course isn't failure — it's growth.
💡 Key Takeaways Keto and carnivore can be powerful tools, but may not be lifelong solutions Gut dysbiosis can develop when microbial diversity is chronically reduced Thyroid function is highly sensitive to long-term energy and carb availability Mental health, digestion, and metabolism are deeply interconnected Symptoms are often rationalized in high-discipline diet cultures Metabolic flexibility and reassessment are key to long-term health Health strategies should evolve as physiology changes
Episode Timestamps:
00:00 — Introduction: Dr. Rachel Brown's background 03:00 — Why keto initially worked 06:30 — Transitioning into long-term carnivore 10:30 — Early warning signs that were easy to dismiss 14:00 — Gut dysbiosis explained 18:00 — Thyroid dysfunction and restrictive diets 22:30 — Mental health implications of chronic restriction 27:00 — When discipline becomes self-harm 31:30 — Reintroducing carbs and gut-supportive foods 36:00 — Metabolic flexibility vs diet identity 41:00 — Lessons learned after 10 years 45:00 — Final thoughts: evolving without shame Connect with Zane Griggs: 🧠 Free Plan: free40plan.com 📲 Instagram: @zanegriggsfitness 🌐 Website: zanegriggs.com Guest Links:
IG: @drrachelsarahbrown https://drrachelsbrown.com
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Low-carb, ketogenic, and carnivore diets have helped a lot of people — myself included — at different stages of their health journey. But what happens when a strategy meant to heal is followed too long without reassessment? In this episode of Healthy AF, I sit down with Dr. Rachel Brown, a psychiatrist and functional medicine practitioner who shares her deeply personal experience after 10 years of ketogenic eating — six of those strictly carnivore. Dr. Brown opens up about the symptoms she believes were connected to long-term carbohydrate restriction, with gut dysbiosis and thyroid dysfunction becoming the most prominent issues. Coming from both a psychiatric and functional medicine background, she brings a rare perspective — one that bridges mental health, metabolism, and digestive health. We explore how restrictive diets can alter the gut microbiome over time, why a lack of fermentable carbohydrates may compromise microbial diversity, and how chronic stress physiology can quietly impact thyroid signaling. Dr. Brown also explains how symptoms can be missed or rationalized in high-discipline health communities, where feeling unwell is often reframed as "adaptation." This is not an anti-keto or anti-carnivore conversation. It's an anti-dogma conversation. We talk about the importance of metabolic flexibility, ongoing self-assessment, and the willingness to evolve as your body's needs change. Dr. Brown emphasizes that healing isn't about ideology — it's about listening to physiology, respecting individual variability, and understanding that no approach should be considered permanent by default. If you've ever wondered whether a diet that once helped you might now be holding you back, this episode offers clarity, nuance, and reassurance that changing course isn't failure — it's growth. 💡 Key Takeaways Keto and carnivore can be powerful tools, but may not be lifelong solutions Gut dysbiosis can develop when microbial diversity is chronically reduced Thyroid function is highly sensitive to long-term energy and carb availability Mental health, digestion, and metabolism are deeply interconnected Symptoms are often rationalized in high-discipline diet cultures Metabolic flexibility and reassessment are key to long-term health Health strategies should evolve as physiology changes Episode Timestamps: 00:00 — Introduction: Dr. Rachel Brown's background 03:00 — Why keto initially worked 06:30 — Transitioning into long-term carnivore 10:30 — Early warning signs that were easy to dismiss 14:00 — Gut dysbiosis explained 18:00 — Thyroid dysfunction and restrictive diets 22:30 — Mental health implications of chronic restriction 27:00 — When discipline becomes self-harm 31:30 — Reintroducing carbs and gut-supportive foods 36:00 — Metabolic flexibility vs diet identity 41:00 — Lessons learned after 10 years 45:00 — Final thoughts: evolving without shame Connect with Zane Griggs: 🧠 Free Plan: free40plan.com 📲 Instagram: @zanegriggsfitness 🌐 Website: zanegriggs.com Guest Links: IG: @drrachelsarahbrown https://drrachelsbrown.com