But if you have hypothyroidism, the situation is more complex. Since this condition slows down your metabolism and affects how your body uses energy, following a strict keto diet can feel like a double-edged sword. Some people thrive on keto, while others notice worsening fatigue, brain fog, or stalled weight loss. The key is not whether you “can” do keto with hypothyroidism, but how you adjust it to support thyroid health.
The Thyroid–Metabolism Connection
Your thyroid gland produces hormones (T3 and T4) that regulate metabolism, energy production, and body temperature. Hypothyroidism means your thyroid isn’t making enough of these hormones, which can cause:
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Fatigue
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Weight gain or difficulty losing weight
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Sensitivity to cold
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Slowed digestion
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Brain fog
Because keto restricts carbs—which play a role in thyroid hormone conversion—going too low-carb for too long can sometimes reduce T3 hormone levels further. That doesn’t mean keto is off-limits, but it does mean adjustments are necessary.
Adjusting Keto for Hypothyroidism
Here are science-backed, practical ways to modify keto so it works better if you have thyroid issues:
1. Don’t Cut Carbs Too Low
Classic keto limits carbs to 20 grams or less per day. For hypothyroidism, this can be too restrictive. Instead, aim for 50–75 grams of net carbs daily, coming from nutrient-dense foods like:
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Sweet potatoes
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Berries
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Squash
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Carrots
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Quinoa (in moderation)
This slightly higher carb intake can support thyroid hormone conversion without knocking you out of fat-burning mode.
2. Focus on Clean Protein
Your thyroid relies on amino acids like tyrosine (found in protein) to produce hormones. Include moderate amounts of:
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Eggs
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Fish (especially salmon and sardines for omega-3s)
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Poultry
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Plant proteins like tofu, tempeh, or edamame
Stay away from processed meats and focus on whole food sources.
3. Get Enough Micronutrients
Certain nutrients are crucial for thyroid function:
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Iodine: Found in seaweed, iodized salt, and fish.
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Selenium: Found in Brazil nuts, sunflower seeds, and tuna.
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Zinc: Found in pumpkin seeds, lentils, and shellfish.
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Iron: Found in leafy greens, beans, and lean red meat (if you eat it).
If your diet lacks these, consider a high-quality supplement (always check with your doctor).
4. Prioritize Healthy Fats
Keto emphasizes fats, but quality matters. Choose fats that reduce inflammation and support hormone balance:
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Avocados
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Olive oil
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Coconut oil (in moderation)
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Nuts and seeds
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Fatty fish
Avoid heavily processed oils like soybean or corn oil.
5. Listen to Your Body
With hypothyroidism, energy levels can fluctuate. If strict keto leaves you drained, consider cyclical keto—where you eat slightly higher carbs 1–2 days a week. This helps refill glycogen, supports thyroid hormones, and keeps energy steady.
6. Work With Your Doctor
Keto isn’t one-size-fits-all. If you’re taking thyroid medication, your carb intake, weight loss, and medication timing may interact. Always consult your doctor or a registered dietitian before making major diet changes.
Final Thoughts
Keto can work for people with hypothyroidism, but strict carb restriction may backfire if it lowers thyroid hormone activity. The smarter approach is a modified keto plan that includes slightly more carbs, nutrient-rich whole foods, and an emphasis on healthy fats and protein. Combine this with good sleep, stress management, and exercise, and you’ll set yourself up for better weight management and overall thyroid health.
👉 Pro Tip: Don’t focus only on the scale. Track energy, mood, and digestion too. Sustainable results come from balance—not extremes.