Does The Keto Diet Mess Up Hormones?

The Role of Carbohydrates in Hormone Health.

Women’s hormones are especially sensitive to calorie and carb restriction. Carbohydrates play a critical role in hormone production, blood sugar regulation, and even ovulation. When you cut carbs too low, it can increase cortisol (your stress hormone), suppress your thyroid, and even lead to irregular or missing periods.

I see so many women in their 30s and 40s who cut carbs or even try a strict keto diet to “fix” their metabolism. However, they often end up feeling exhausted, anxious, foggy, and more inflamed than before.

Why does this happen? Your brain needs glucose to feel safe. Without it, your body goes into stress mode and cortisol spikes. This might manifest as anxiety, poor sleep, low energy, hair loss, mood swings, or a metabolism that feels completely stalled out.

When cortisol levels remain elevated, it sends the body into HPA dysfunction. This response tells the body to go into "fat storage mode." The body doesn’t know how long it will be in a high-stress state, so it wants to conserve and store as much excess energy as possible. This is the opposite of what most women desire.

This is why women who stop keto, because it is not sustainable, often see the weight come back on, sometimes with additional pounds.

What About Keto for PCOS or Insulin Resistance?

While it’s true that a strict low-carb or keto diet can lower insulin levels, it’s crucial to work with a dietitian to make sure you're still getting the nutrients you need. As a dietitian, my goal is to personalize macros and sync your diet with your menstrual cycle to avoid disrupting natural hormone fluctuations.

The Blood Sugar - Thyroid Connection

Insulin is necessary for converting the inactive thyroid hormone T4 into the active thyroid hormone T3. When insulin levels drop too fast or remain low for too long, it can lead to low T3 levels in the body. This can result in hypothyroid symptoms, which include:

• Fatigue

• Weight gain

• A puffy face

• Trouble tolerating cold

• Joint and muscle pain

• Constipation

• Dry skin

• Dry, thinning hair

  
  

When I work with clients who have PCOS or insulin resistance, I recommend a moderately low-carb diet tailored to each woman. There should always be a strong emphasis on complex carbohydrates, resistant starch, fiber, and polyphenols.

Macros are only one part of the equation. We need to also make sure to be supporting gut health, microbiome, stress response, and metabolism.

Do I Need To Be Gluten-Free and Dairy-Free?

The best diet is one that is personalized for you and your body. Factors like body type, age, genetics, and personal preferences should all influence your dietary choices.

Women can absolutely eat a healthy, balanced diet while being gluten-free or even grain-free, but that doesn't mean it's necessary. The same goes for those who choose not to eat animal protein. Having a dietitian help you build an eating routine and simple meals that meet your nutrient needs is important to prevent nutrient deficiencies.

I recommend women to avoid extreme diets like keto, and instead focus on hormone-supporting nutrition and smaller adjustments to their current base diet. Such as bulking up:

✔️ High-quality protein

✔️ Healthy fats (make sure to use plenty of olive oil)

✔️ Fiber and colorful veggies

✔️ Slow carbs (like sweet potatoes, root veggies, beans, fruits, and whole grains)

These foods help stabilize blood sugar, reduce inflammation, and support happy hormones.

As a Hormone Health Dietitian, I’m here to remind you: If your diet is causing burnout, it’s not working for you.

Want to Go Deeper?

If you suspect your hormones are out of sync, personalized nutrition and functional hormone testing can uncover what’s really going on. I offer 1:1 consultations and a comprehensive hormone testing package that dives into cortisol, estrogen, progesterone, organic acids, inflammatory markers, and more.

Link to My Foundations of Hormone Balance Program

Link to Comprehensive Hormone Testing Package

Liz Riesen, RD, CD

Registered dietitian and hormone health coach helping women address hormone imbalances, increase energy, and lose weight naturally. As a busy mom, I know that you need a clear and realistic approach you can fit into a hectic lifestyle. I developed my Foundations of Hormone Balance Method to meet this need. Helping women feel confident and comfortable in their bodies and with food is my passion.

Follow me @lizriesen