Optimal thyroid function can be a really essential part of losing weight and keeping it off long-term.  Whether you know that you have an under-active thyroid or hypothyroidism, or you just suspect that you might, here are three of the most common causes of low thyroid hormones.

1. Stress

Stress plays a crucial role in thyroid dysregulation, and interferes with the production of thyroid hormones through the release of stress hormones including cortisol.  Stress hormones produced by the adrenal glands inhibit TSH (thyroid stimulating hormone) release, thereby suppressing thyroid function. Higher cortisol (stress hormone) levels have been consistently linked to thyroid disorders, including hypothyroidism.  

Reducing and managing stress levels is an essential part of improving thyroid health and thyroid hormone levels.

2. Nutritional deficiencies

There are two main nutrients that are implicated in thyroid function: iodine and selenium.

Iodine is a common deficiency worldwide, and can be particularly depleted during pregnancy when the mother’s iodine is passed onto the baby.  Iodine is found in seafoods and kelp (seaweeds), and is added to processed foods such as salt, though this form of iodine is not generally well-absorbed.  Increasing seafoods, including seaweed, in your diet is essential for thyroid function.

Selenium is needed for the conversion of T4 to T3, which are two thyroid hormones.  If selenium deficiency is present, then T4 will not be converted to T3 effectively, which results in low T3 and therefore, under-active thyroid or hypothyroidism.  Selenium deficiency is common in Australia due to soil depletion.  Consuming selenium-rich foods such as brazil nuts, tuna, oysters, salmon, chicken liver and sesame seeds may be helpful in improving your thyroid function.

3. Mercury

Exposure to mercury may increase your risk of hypothyroidism, especially if iodine levels are low.  Mercury is found in amalgam (silver) tooth fillings and in large fish such as tuna.


If you’d like more information on low thyroid function, or hypothyroidism, read my post: 5 Symptoms of an Underactive Thyroid