The Gut-Thyroid Connection: Why Perimenopause Changed Everything for Me

If you had told me a few years ago that my gut health and thyroid were connected, I probably wouldn’t have thought much of it. I understood the basics—eat well, exercise, get enough sleep—but I never fully grasped how much my microbiome could influence my metabolism, energy, and hormone balance. That all changed when I entered perimenopause and was diagnosed with hypothyroidism.

I had always taken care of myself, but suddenly, I felt like my digestion had slowed to a crawl. I was bloated all the time, my energy was dipping, and I started experiencing symptoms that pointed to leaky gut—food sensitivities, skin issues, and what felt like constant inflammation. I knew I needed to look deeper than just my thyroid and address the gut-thyroid connection.

How the Gut Impacts Thyroid Function

Your gut and thyroid are in constant communication, and when one is out of balance, the other often suffers. One of the biggest ways the gut affects thyroid health is through T4 to T3 conversion. The thyroid produces mostly T4 (inactive thyroid hormone), but for your body to actually use it, T4 must be converted into T3 (the active form). About 20% of this conversion happens in the gut, so if your microbiome is out of balance, your ability to produce active thyroid hormone can drop significantly.

For me, this meant that even though I was taking thyroid medication, I still wasn’t feeling great. My digestion was sluggish, I was constantly bloated, and I felt like my metabolism had hit a wall. Testing confirmed that I had low T3 levels, which made perfect sense given my gut issues.

How Hypothyroidism Affects the Gut

The gut-thyroid axis works both ways. Just as the gut influences thyroid function, an underactive thyroid can slow down digestion, leading to constipation, bloating, and slow transit time. One of the first things I noticed when my thyroid levels dropped was that my gut was no longer working efficiently. Food would sit in my stomach longer, and I often felt heavy and sluggish after meals.

This is because thyroid hormones help regulate gut motility, ensuring food moves through the digestive system properly. When thyroid function slows down, so does digestion, creating an environment where bad bacteria can overgrow and disrupt gut balance. This can lead to issues like SIBO (small intestinal bacterial overgrowth), leaky gut, and microbiome imbalances.

I also started noticing increased food sensitivities—foods I had once eaten without a problem suddenly caused bloating and discomfort. This was a clear sign that my gut lining had become more permeable (aka leaky gut), allowing food particles and toxins to escape into my bloodstream and trigger inflammation.

What I Did to Support My Thyroid and Gut Health During Perimenopause

Once I understood the gut-thyroid connection, I knew I needed to support both systems to feel better. Here’s what worked for me:

1. Eating More Fiber and Variety

I made a conscious effort to eat veggies and fruit with every meal and aimed for at least 30 different plant varieties per week to feed my gut microbiome. This included cruciferous vegetables (which support liver detox and estrogen balance), root vegetables for prebiotics, and polyphenol-rich foods like berries and dark chocolate. The more diverse my diet, the better my gut and thyroid function became.

2. Drinking More Water

With slow gut motility, hydration is key. I increased my water intake to at least 2 liters a day, ensuring I stayed hydrated to support digestion and thyroid function. I also started adding electrolytes to help with absorption and keep my energy levels stable.

3. Managing Stress and Sleep

Perimenopause brought cortisol deregulation, which can disrupt both the thyroid and the gut. I began prioritizing sleep, breathwork, and nervous system regulation. This included consistent bedtime routines, red light therapy, and guided meditation to help lower cortisol and support my adrenals.

4. Taking Targeted Supplements

I incorporated key supplements to support my gut-thyroid axis:

• Magnesium – Essential for relaxation, bowel motility, and thyroid function

• A High-Quality Probiotic – Helped restore my gut microbiome and improve digestion

• Motility Activator – Helped keep things moving and reduced bloating

  
  

5. Testing My Bloodwork, Cortisol, and Microbiome Yearly

One of the biggest game-changers for me was regular testing. Each year, I check:

• Thyroid panel (TSH, Free T3, Free T4, Reverse T3, and TPO thyroid antibodies)

• Cortisol levels (since stress plays a huge role in thyroid function)

• Microbiome composition (to assess gut diversity and dysbiosis)

Testing allows me to make data-driven decisions instead of guessing what’s wrong. For example, when I saw that my Reverse T3 was high, I knew I needed to focus more on stress management and liver detoxification. When my microbiome showed signs of low bacterial diversity, I doubled down on fiber and prebiotics.

Final Thoughts: Your Gut and Thyroid Work Together

If you’re struggling with thyroid issues, slow digestion, or unexplained bloating, don’t overlook the gut-thyroid connection. Perimenopause adds another layer of complexity, but by addressing gut health, supporting thyroid conversion, and reducing inflammation, you can start feeling like yourself again.

If I’ve learned anything, it’s that you can’t just treat one system in isolation—healing your gut supports your thyroid, and optimizing your thyroid improves digestion. It’s all connected.

Have you noticed changes in your gut or thyroid function during perimenopause? Drop a comment below—I’d love to hear your experience! ✨