I was finally diagnosed with hypothyroidism and started on thyroid replacement, so why do I keep gaining weight?


There are a few possibilities as to why you are continuing to gain weight in spite of starting on thyroid replacement hormone:

  • The type of thyroid replacement medication and/or dosage may not be meeting your body’s needs.
  • You may be deficient in trace minerals and/or other nutritional co-factors.
  • You may have other underlying health issues that have not been addressed.

If you were put on a T4-only drug like Levothyroxine, Synthroid, or Levoxyl, you may not be able to efficiently convert this “storage form” of the thyroid hormone to its active form of T3 in the body. Worse, yet, your body may be converting it to another form called Reverse T3, which is inert in the body. When this happens, your original symptoms of weight gain, constipation, body aches, fatigue, hair loss and intolerance to cold may remain or even worsen. Ideally your doctor will evaluate more than just your TSH (thyroid stimulating hormone) and consider looking at the free (or unbound) forms of T3 and T4 and Reverse T3 on your lab work.

Another possibility for the ongoing weight gain is a mineral or nutritional deficiency in your body. The thyroid, along with all other metabolic activities in our body, requires a myriad of minerals and vitamin co-factors to up-regulate or down-regulate normal metabolic activity in the body. To optimize thyroid function, our body requires tyrosine, iodine, iron, selenium, zinc, B-6, B-12, vitamin A and vitamin D…just to name a few.

Remember, our thyroids do not exist in a vacuum, so the thyroid gland is also dependent on how other endocrine glands are functioning and how well “communication” between these glands is working. For example, if you have been through chronic stress of any kind, your adrenal glands have been working overtime to keep you going by producing cortisol and adrenaline…eventually, you can “burn out” the adrenals and they will produce less and less cortisol over time. This commonly leads to cravings for high carb foods and fats that only further compromise your blood sugar and keep the vicious cycle of weight gain and frustration continuing. (Realize this is a complicated process and I have oversimplified here for the sake of brevity).

Unaddressed insulin resistance can start years before full-blown diabetes is diagnosed and is a big contributor to weight gain. Imbalances in the sex hormones related to irregular menstruation, pregnancy, or menopause can also wreak havoc with the thyroid and other metabolic activities in the body. Also, undiagnosed auto-immune conditions and other inflammatory processes can also influence weight gain and lead to hypo functioning thyroid symptoms.

As you can see, there is no simple answer to your question. Properly addressing any health concern requires appropriate testing, nutritional evaluation and thorough screening by a qualified health professional.

The information contained in this article is for information and education purposes only and is not medical advice. Do not use this information as an alternative to obtaining medical advice from your physician or other professional healthcare provider. Always consult with your physician or other professional healthcare provider about any medical conditions you are experiencing. If you are experiencing a medical emergency, contact your local emergency services for help.


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