Still Tired After “Normal” Thyroid Tests?

Here’s What Your Doctor Might Be Missing

Do you wake up feeling exhausted, no matter how much sleep you get? Battling brain fog, weight gain, or constantly feeling cold? If you’ve already had your thyroid tested and were told everything is “normal,” but you still feel off, there might be more to the story.

What most doctors check on a standard thyroid panel, TSH (thyroid-stimulating hormone) and T4 (thyroxine), only gives part of the picture. The missing piece? T3, the active thyroid hormone responsible for powering your metabolism, energy, and brain function. If your body isn’t converting T4 into enough T3, or if your cells can’t use that T3 properly, fatigue and other thyroid-related symptoms can persist, even if your blood tests say otherwise.

Let’s break down why this happens, why medication alone doesn’t always fix it, and what you can do to start feeling like yourself again.

How Your Thyroid Controls Energy

Think of your thyroid as your body’s internal thermostat. It produces hormones that regulate temperature, metabolism, and energy levels. The two primary hormones are:

• T4 (thyroxine) – The inactive “storage” hormone.
• T3 (triiodothyronine) – The active hormone that fuels energy and metabolism.

T4 must be converted into T3 before your body can use it. Once active, T3 enters your cells and turns on the genes that keep your body running, everything from burning calories to keeping your brain sharp.

If your body isn’t making enough T3, or your cells don’t respond to it, fatigue, brain fog, and sluggish metabolism can set in, even if your TSH and T4 levels appear “normal.”

Why Levothyroxine Doesn’t Always Work

The standard treatment for hypothyroidism is levothyroxine, a synthetic version of T4. For some, this works well. But for many others, symptoms linger. That’s because levothyroxine doesn’t provide T3, it just adds more T4 and assumes your body will convert it.

Here’s what can interfere with that conversion:

• Nutrient deficiencies: Your body needs iodine, selenium, zinc, magnesium, and iron to turn T4 into T3.
• Chronic stress: Elevated cortisol increases reverse T3 (rT3)—an inactive form that blocks T3 from working.
• Inflammation and gut issues: Most T3 conversion happens in the gut and liver. Poor digestion or inflammation slows this down.
• Low receptor sensitivity: Even with enough T3, your cells might not “hear” the signal if they lack magnesium or other co-factors.

Bottom line? More T4 doesn’t help if your body can’t use it.

The Thyroid-Supportive Diet: Fuel for Energy

Food is your thyroid’s foundation. To function optimally, your body needs the right nutrients in the right amounts. Focus on:

• Iodine: Found in seaweed, fish, eggs, dairy, and iodised salt.
• Selenium: In Brazil nuts, tuna, sunflower seeds, and mushrooms.
• Zinc: Found in pumpkin seeds, shellfish, beef, and lentils.
• Magnesium: In leafy greens, avocados, nuts, and seeds.
• Iron: From grass-fed beef, spinach, and organ meats.
• Vitamin D: From sunlight, fatty fish, and eggs.

Many people with thyroid issues are low in iodine and magnesium, key players in hormone production and receptor function.

Lifestyle Tweaks That Make a Big Difference

Your thyroid doesn’t work in isolation. It’s affected by your stress levels, sleep quality, and blood sugar balance. Here’s how to support it:

• Manage stress: Chronic stress disrupts T3. Try meditation, breathwork, and adaptogens like ashwagandha.
• Prioritise sleep: Aim for 7–9 hours. Avoid screens before bed and build a calming nighttime routine.
• Balance blood sugar: Ditch the blood sugar rollercoaster. Eat balanced meals with protein, fat, and fibre.
• Exercise wisely: Too much cardio can drain your thyroid. Focus on strength training, walking, and yoga.

Supplements That Support Thyroid Health

If your diet alone isn’t enough, supplements can fill the gaps and support optimal thyroid function:

• Iodine, selenium, and zinc to support hormone production and conversion.
• Magnesium (glycinate or malate): Helps T3 bind to receptors.
• Vitamin D3 + K2: Supports immune and thyroid function.
• Iron (if deficient): Best absorbed with vitamin C.
• Adaptogens: Ashwagandha, Rhodiola, and holy basil help manage stress and support thyroid-adrenal balance.
• Thyroid glandular: Provide natural hormone support for those not responding to T4 meds.

The Bottom Line

If you’re tired all the time, even after a good night’s sleep, and your thyroid tests come back “normal,” don’t ignore your symptoms. There’s more to thyroid health than just TSH and T4.

By looking deeper into T3 levels, reverse T3, and cellular sensitivity and supporting your body through nutrition, lifestyle, and targeted supplements, you can finally start to feel like yourself again.

Your energy can come back, it just starts with understanding what your body is really trying to tell you.

Thanks for reading!

Louise x

Learn more about Louise here