Thyroid Medications and Weight Loss

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It can be challenging to lose weight when you have hypothyroidism, and your thyroid medications may have something to do with it.

Getting the dose just right is critical, as is the timing of when you take it. In some cases, you may need to supplement with another medication.

For the sake of your overall health, as well as your weight-loss efforts, it's important to work with your healthcare provider to get the most out of thyroid hormone therapy.

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Aiding Absorption

For thyroid medication to be effective, it needs to be absorbed properly by your body. Here's how to ensure that nothing interferes with maximum absorption:

  • Take your medication in the morning and wait at least an hour before eating breakfast or drinking regular or decaf coffee or milk. Wait at least three to four hours before taking any supplements that contain iron or calcium, or before consuming products such as calcium-fortified juice.
  • If you are taking Synthroid brand levothyroxine, keep in mind that Synthroid contains both acacia and lactose, which are allergy-provoking ingredients for some people. If you suspect you might be allergic to these, consider switching to another brand. 
  • If you have digestive issues or any digestive conditions, such as irritable bowel syndrome, Crohn's disease, or a history of bariatric surgery, talk to your healthcare provider about Tirosint. This is a specialized, hypoallergenic gelcap containing liquid levothyroxine that is designed to improve absorption in certain patients.

Finding the Right Dose

It's important that you take the right amount of Synthroid or another thyroid hormone replacement drug. Some healthcare providers may prescribe only enough medication to get your thyroid-stimulating hormone (TSH) level into the upper end of the reference range, close to the cutoff for hypothyroidism.

This may not be enough to resolve your symptoms or optimize your metabolism. Many thyroid patients and healthcare providers find that a TSH level below 2.0 is optimal for resolution of symptoms. This is also the optimal level for women of reproductive age. If your TSH is at the higher end of the reference range, talk to your healthcare provider about increasing your dosage of thyroid medication.

If you're hypothyroid and need to lose weight, talk to your healthcare provider to make sure you're on the right dose of the right drug and are taking it at the right time. With some fine-tuning of your treatment, your weight-loss efforts should begin to pay off.

When One Drug Isn't Enough

Levothyroxine drugs like Synthroid are synthetic forms of the thyroid hormone thyroxine, also known as T4. When everything works perfectly, your body should convert the T4 into the second key thyroid hormone, triiodothyronine, known as T3. T3 is the active hormone that helps facilitate energy and helps oxygen reach your cells.

Research shows, however, that in a subset of thyroid patients, this conversion process is faulty. Whether due to genetic changes, stress, or nutritional deficiencies, these patients fail to effectively convert enough T4 into T3.

If you fall into this category, you may find that even after being treated with levothyroxine, you may have hypothyroidism symptoms, such as fatigue, hair loss, or brain fog. If this is the case, you might benefit from the addition of T3 to your levothyroxine.

Ask your healthcare provider to test your T3. If you have low or low-to-normal levels, you may be a candidate for supplementation with Cytomel (liothyronine) or a compounded, time-released formulation of this medication.

Note that compounded medications can be difficult to accurately dose, however, as it is very hard to determine the exact quantities of T3 and T4 in each pill. Compounded formulas can be difficult to control and could lead to overly suppressed TSH levels and low free T4/high T3 levels in the blood.

It's also worth noting that adding T3 to your regimen is still relatively experimental: There is not enough clinical evidence to support this practice in every patient.

Rethinking Medications

Some thyroid patients try a levothyroxine drug, add a T3 drug, and still can't resolve symptoms. If that is your experience, you may want to talk with your healthcare provider about trying a natural desiccated thyroid (NDT) drug like Nature-throid or Armour Thyroid. There is also a generic version of NDT known as Thyroid NP. 

There is limited research on NDT, but one study found that NDT was a safe and effective alternative to levothyroxine drugs, and resulted in more weight loss for patients.

Women seeking to become pregnant or who are pregnant should only be on levothyroxine, since T3 or its combinations do not cross the placenta.

A Word From Verywell

While it's not related to Synthroid or other thyroid drug treatment, there is a link between hypothyroidism and the risk of increased blood sugar levels and type 2 diabetes. If you have optimized your hypothyroidism treatment and are still struggling to lose weight, talk to your healthcare provider about having your fasting glucose and hemoglobin A1C (HA1C) tested. If levels are high, changes to your diet and exercise habits, as well as type 2 diabetes medications such as metformin, may help normalize your blood sugar levels and make your weight-loss efforts more successful.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Chakera AJ, Pearce SH, Vaidya B. Treatment for primary hypothyroidism: current approaches and future possibilities. Drug Des Devel Ther. 2012;6:1-11. doi:10.2147/DDDT.S12894

  3. Centanni M, Benvenga S, Sachmechi I. Diagnosis and management of treatment-refractory hypothyroidism: an expert consensus report. J Endocrinol Invest. 2017;40(12):1289-1301. doi:10.1007/s40618-017-0706-y

  4. Hennessey JV, Espaillat R. Current evidence for the treatment of hypothyroidism with levothyroxine/levotriiodothyronine combination therapy versus levothyroxine monotherapy. Int J Clin Pract. 2018;72(2). doi:10.1111/ijcp.13062

  5. Hoang TD, Olsen CH, Mai VQ, Clyde PW, Shakir MKM. Desiccated Thyroid Extract Compared With Levothyroxine in the Treatment of Hypothyroidism: A Randomized, Double-Blind, Crossover StudyThe Journal of Clinical Endocrinology & Metabolism, 2013 May;98(5):1982-90. doi:10.1210/jc.2012-4107

Additional Reading

By Mary Shomon
Mary Shomon is a writer and hormonal health and thyroid advocate. She is the author of "The Thyroid Diet Revolution."