Why Your THYROID Medication Isn't Working (And What To Do Instead)

Dr. Stengler: Have you wondered why you're not losing weight with your new thyroid medication? I see a lot of patients who are overweight, get diagnosed with hypothyroidism, are put on thyroid medication, and expect to lose weight and feel better — better energy, better clarity of mind. That certainly is possible with the right thyroid dose and medication. But let's look at this more closely.

By far the most common thyroid medication given to Americans is the synthetic thyroid known as levothyroxine — you may know it by brand names like Levoxyl or Synthroid. This medication is T4. Our thyroid gland does make both T4 and T3, but it makes more T4 because the liver and kidneys convert T4 into T3. And here's the key point: T3, also known as liothyronine, is the most metabolically active thyroid hormone. When thyroid hormone gets into your cells, it attaches to receptors, enters the cell, and acts on your DNA — affecting your metabolism and helping your mitochondria burn energy at a higher rate.

So it does stand to reason that if low thyroid levels are corrected, you could lose weight. But for many people on standard thyroid medication, that's not happening — and the reason is likely that they're not converting enough T4 into the more biologically active T3. This can be tested with standard blood labs. Most doctors don't run these tests, but simply ask your doctor to add total T3 and free T3 to your panel — alongside the standard TSH and free T4 — so you can see what your T3 levels actually are. If they're low or deficient, you need a different approach.

There are two ways to address low T3 in someone on standard thyroid medication. First, improve diet and exercise, which can help balance stress hormones and support the conversion of T4 to T3. Make sure you're also getting the nutrients required for that conversion — selenium is very important for this. Second, you can add T3 to the treatment plan. In regular pharmacies, this is known as Cytomel. Compounding pharmacies — which can prepare any dose in bioidentical form — carry it as liothyronine. Getting T3 levels up with one of these protocols can make a substantial difference in metabolism.

But the benefits go beyond metabolism. With optimal T3 levels you should also see better energy, better mood, better focus and concentration, better skin health, improved digestion, and many other improvements — because thyroid hormone affects essentially every cell in your body.

So if you're on thyroid medication and your metabolism still seems off, get your T3 levels checked. Work with a doctor who can optimize them, and more often than not you'll find that your metabolism — and much more — improves as a result.

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