Thyroid Hormone & Weight Loss

 Thyroid Hormone & Weight Loss. Is This The Single Most Common Cause of Weight Loss Ressistance? 

Isn't it frustrating when you try healthy diet & exercise and nothing seems to change?

You even try Keto Diet faithfully and the only thing that seems to change when you stand on the scale is - NOTHING?

Its about time we checked your thyroid function.

Stay with me for a minute...

Arguably the most common underlying hormonal issue people have when they struggle to lose weight (and keep it off) is impaired thyroid function.

The thyroid gland is the quintessential “Switch” of the body since it plays a major role in regulating the metabolic rate.1

However, while many people presume that producing high amounts of thyroid hormone is ideal for weight loss, that’s not necessarily the case.

Having insufficient levels of thyroid hormones (i.e. hypothyroidism) can be just as deleterious as having excessively high levels (i.e. hyperthyroidism).

What is Ahead...

This article will discuss the ways in which thyroid function impacts weight loss as well as what you should do from a dietary and supplement standpoint to help encourage proper thyroid hormone production.

What is the Thyroid Gland?

The thyroid gland is a butterfly-shaped organ in the body that secretes thyroid hormones which control metabolism. This gland sits about halfway up the base of the front neck and runs along the trachea.

Thyroid Gland 

There are two lobes of the thyroid gland that sit adjacent to the windpipe.

There us a small band of thyroid tissue called the isthmus that runs horizontally across the trachea and connects these lobes.

During the prenatal phases of infant development, the thyroid gland sits near the back of the tongue and slowly migrates down towards the front of the neck prior to birth.

In exceptionally rare cases, the thyroid gland may not make this migration from the tongue to the neck, or it may translocate all the to the sternum.

In each case, surgery is usually performed to move/remove the thyroid tissue so that there aren’t any complications with breathing and eating.

While anatomical thyroid complications are somewhat rare, physiological issues related to thyroid hormones are quite prevalent.

In fact, it’s suggested that upwards of one in every 10 adults has hypothyroidism and that roughly one in every eight women will experience thyroid complications during their lifetime.2

What’s more worrisome is that estimates suggest as many as 60% of people with a thyroid disorder are unaware of the issue.

Thus, it’s no wonder people who have undiagnosed thyroid problems are left bewildered and frustrated when they struggle to lose weight.

All in all, you should have routine thyroid labs done before you embark on any weight loss plan just to make sure your thyroid hormones are in a healthy range.

The most relevant blood tests to have done include levels of free thyroxine (T4), free triiodothyronine (T3), and thyroid-stimulating hormone (TSH). Most general care practitioners will order these panels for you.

How Does the Thyroid Gland Work?

Thyroid hormones are derivatives of the essential amino acid L-tyrosine. The two most important thyroid hormones in the body are thyroxine (T4) and triiodothyronine (T3); the former contains four iodine atoms in its molecular structure while the latter contains three iodine atoms (hence the names “T4” and “T3”).

As such, one of the primary roles of the thyroid gland is to make use of the iodine the body.

Iodine is an essential trace mineral that you must consume through diet and/or supplementation as the body doesn’t synthesize it endogenously.

In other words, if you don’t consume adequate iodine, then your body won’t be able to produce a sufficient amount of thyroid hormones: thyroxine (T4) and triiodothyronine (T3).

In fact, thyroid tissue is comprised of the only cells in the entire body that are capable of absorbing iodine.

Within these cells, L-tyrosine and iodine are used to synthesize both T4 and T3. (T4 is also converted to T3 in many tissues and organs, particularly the brain, skeletal muscle, and gut.)

Thus, T4 is typically thought of as the “parent” thyroid hormone, but T3 is the more potent of the two.

On a molar scale, T3 is roughly 20-fold more potent than T4 and is thus defined as “active” thyroid hormone.3

The body also produces T2 and T1, but they are merely byproducts of and precursors to T3/T4, and they don’t seem to serve much biological value beyond that.4

How Are Thyroid Hormones Produced?

Similar to the axis that controls sex hormone production, the thyroid gland is not an autonomous organ but rather it is regulated by the pituitary gland - a tiny organ that sits at the base of the brain.

The pituitary gland is essentially the “control center” that dictates the production of many hormones in the body by secreting its own distinct hormones.

In the case of regulating the thyroid gland, the pituitary gland produces thyroid-stimulating hormone (TSH), which tells the thyroid that the body needs more T4/T3.

Hence, when TSH levels are high, thyroid hormone levels tend to increase accordingly (and vice versa).

Inversely, if your body naturally produces high amounts of T3 and/or T4 (or you take thyroid hormone medication), your pituitary will sense this and reduce the production of TSH.

(This is called a “negative feedback loop” and is how much of the human endocrine system works.)

This is why the pituitary gland is much like the body’s “internal thermostat,” and the thyroid gland is the “furnace” that secretes heat-producing hormones.

But to make matters even more intricate, the production of TSH (via the pituitary) is actually regulated by the hypothalamus - another gland in the brain that secretes TSH-releasing hormone (TRH).

Therefore, the hypothalamus is analogous to the person who actually changes the thermostat (which, in this case, is the pituitary gland).

Unfortunately, we aren’t able to control our body’s internal thermostat on a whim like a household thermostat.

However, we can consume specific nutrients and use various dietary supplements that help encourage healthy thyroid production (which we will touch on soon). 

What Do Thyroid Hormones Do?

It might help to think of T3/T4 (thyroid hormones) as being like fire logs that you toss into a furnace to keep the fire burning.

Thyroid hormones ultimately regulate metabolic rate and body temperature by acting on virtually every cell in the body.

Naturally, if you constantly feel cold (despite warm weather), have a low resting heart rate, and struggle to work up a sweat while exercising, your thyroid may not be producing enough T4/T3 (i.e. hypothyroidism).

On the flip side, if you’re constantly hot, shaky, have a rapid resting heart rate, and sweat easily, your thyroid may be overactive (i.e. hyperthyroidism).

Consequently, thyroid hormones (particularly T3) play a big role in weight loss and body composition.

What Is Metabolism?

The term “metabolism” properly refers to the summation of every molecular reaction that occurs in the body (specifically within cells), and these reactions are necessary for life.

These metabolic reactions are classified as being either catabolic or anabolic; catabolic reactions break down substrates to give off energy (heat/calories) while anabolic reactions use free energy to construct complex molecules and cellular components.

For instance, you might recall from the Cortisol chapter that glycolysis is a catabolic process that involves the breakdown of carbohydrates/sugar to create free energy.

The breakdown of stored body fat (adipose tissue) to liberate energy is another example of a catabolic process.

On the contrary, muscle protein synthesis is an anabolic process where free energy is used (in conjunction with amino acids) to produce muscle proteins.

As such, both catabolic and anabolic processes have their place in promoting weight loss and helping you get leaner.

To put it plainly: metabolism refers to the highly intricate system of molecular reactions occurring in cells that are essential for existence, and these reactions (particularly anabolic ones) have a requisite energetic input (which is exactly why we need to consume nutrients/calories and water to survive).

Thyroid Hormones and Metabolism

Research demonstrates that thyroid hormones (especially T3) have both catabolic and anabolic effects on protein metabolism throughout the human body.5

Thyroid hormones are also well-known to stimulate lipolysis and fatty acid oxidation (which is conducive to weight loss).6

This is a physiological fact that is readily noticeable among the general population, as individuals with hyperthyroidism tend to be scrawny and have a hard time building muscle; while those with hypothyroidism tend to gain body fat easier and struggle to lose weight even while eating a low-calorie diet and/or exercising regularly.

Naturally, when people with hypothyroidism struggle to lose weight, the issue resolves upon restoration of healthy thyroid hormone production (their body temperature and heart rate increase as well).

Conversely, those with hyperthyroidism may be prescribed drugs that inhibit thyroid hormone production so that they can put on weight and come down to a normal body temp and heart rate.

On that note, let’s take a look at how you can support healthy thyroid function through your diet and supplement regimen.

Foods to Eat for Healthy Thyroid Function

In general, the most important nutrients for healthy thyroid function are L-tyrosine, iodine, and selenium.

To reiterate, L-tyrosine is the essential amino acid precursor to T3 and T4, while iodine is an integral component of thyroid hormone structure.

Selenium is a trace mineral that acts on various enzymes to help increase the synthesis of T3 and T4.

For weight loss, your best bet is to eat a diet rich in low-carb foods that are high in these nutrients. Examples of foods that fit this bill are:

  • Pink Himalayan sea salt
  • Cod
  • Shrimp
  • Whole eggs
  • Tuna
  • Salmon
  • Ground beef
  • Green beans
  • Watercress
  • Kelp
  • Wakame
  • Dried seaweed
  • Brazil nuts
  • Cheese

These foods are all rich in iodine and/or selenium, in addition to being good sources of L-tyrosine.

Try incorporating at least 4-5 servings (total) of these foods in your daily diet, it will only help with regards to your thyroid levels.

Supplements for Thyroid Function and Weight Loss

To complement the above food choices, there are a variety of dietary supplements to consider using for promoting healthy thyroid function and weight loss.

In general, the following supplements will help increase thyroid production (particularly in those who have lower thyroid hormone levels).


Recall from earlier that the primary role of the thyroid gland is to utilize iodine, as thyroid tissue contains the only cells in your body that are capable of absorbing it.

Naturally, individuals who lack iodine are more likely to experience thyroid complications.7

Since iodine is a key component of thyroid hormones, supplementing with potassium iodide (100-250 mcg per day) is one way to help you get a sufficient amount of this trace mineral.

Alternatively, Kelp is a herbal alternative for iodine especially when used with adaptogen, Ashwagandha.


Research shows that a deficiency of selenium is associated with a greater incidence of subclinical and clinical hypothyroidism.8

Interestingly, supplementing with selenium (up to 200 mcg per day) has been shown to significantly improve thyroid production in those who were previously deficient in the mineral.9

Vitamin E and Vitamin D3

Vitamin E and vitamin D3 are key micronutrients that have been shown to promote thyroid hormone production and reduce oxidative stress, especially in patients with thyroid autoimmune disorders and hypothyroidism.10,11

It’s best to take about 400 IU of D-alpha tocopheryl (vitamin E) and 2,000 IU of cholecalciferol (vitamin D3) per day for optimizing thyroid function.

Rhodiola Root Extract

Rhodiola rosea is broadly defined as an adaptogenic herb and is known to have a variety of actions throughout the body, mainly due to its exclusive phytochemical composition that provides salidroside and rosavins.

Research suggests that supplementing with rhodiola root extract (500 mg per day) may support the HPT (hypothalamic-pituitary-thyroid) axis and weight loss.12


Guggulsterone is a phytosteroid present in the resin of the guggul plant, Commiphora mukul

Research suggests it may boost metabolism by increasing T3/T4 levels and even counteracting the effects of thyroid-suppressing agents, thereby encouraging continual weight loss on a calorie-controlled diet.13

It appears that about 750 mg of a guggulsterone supplement per day is an efficacious dose for thyroid function and weight loss.



  1. Silva, J. E. (1995). Thyroid hormone control of thermogenesis and energy balance. Thyroid, 5(6), 481-492.
  2. Unnikrishnan, A. G., Kalra, S., Sahay, R. K., Bantwal, G., John, M., & Tewari, N. (2013). Prevalence of hypothyroidism in adults: An epidemiological study in eight cities of India. Indian journal of endocrinology and metabolism, 17(4), 647.
  3. CHOPRA, I. J., CARLSON, H. E., & SOLOMON, D. H. (1978). Comparison of Inhibitory Effects of 3, 5, 3′-Triiodothyronine (T3), Thyroxine (T4), 3, 3,′, 5-Triiodothyronine (rT3), and 3, 3′-Diiodothyronine (T2) on Thyrotropin-Releasing Hormone-Induced Release of Thyrotropin in the Rat in vitro. Endocrinology, 103(2), 393-402.
  4. Goglia, F. (2005). Biological effects of 3, 5-diiodothyronine (T 2). Biochemistry (Moscow), 70(2), 164-172.
  5. Rooyackers, O. E., & Nair, K. S. (1997). Hormonal regulation of human muscle protein metabolism. Annual review of nutrition, 17(1), 457-485.
  6. Pucci, E., Chiovato, L., & Pinchera, A. (2000). Thyroid and lipid metabolism. International Journal of Obesity, 24(S2), S109.
  7. Zimmermann, M. B., & Boelaert, K. (2015). Iodine deficiency and thyroid disorders. The Lancet Diabetes & Endocrinology, 3(4), 286-295.
  8. Shi, B. (2016). The exploration and discovery of the impacts of selenium on thyroid. Chinese Journal of Endocrinology and Metabolism, (1), 4-5.
  9. Köhrle, J. (2015). Selenium and the thyroid. Current Opinion in Endocrinology & Diabetes and Obesity, 22(5), 392-401.
  10. Sarandöl, E., Taş, S., Dirican, M., & Serdar, Z. (2005). Oxidative stress and serum paraoxonase activity in experimental hypothyroidism: effect of vitamin E supplementation. Cell Biochemistry and Function: Cellular biochemistry and its modulation by active agents or disease, 23(1), 1-8.
  11. Goswami, R., Marwaha, R. K., Gupta, N., Tandon, N., Sreenivas, V., Tomar, N., ... & Agarwal, R. (2009). Prevalence of vitamin D deficiency and its relationship with thyroid autoimmunity in Asian Indians: a community-based survey. British Journal of Nutrition, 102(3), 382-386.
  12. Hamidpour, R., Hamidpour, S., Hamidpour, M., Shahlari, M., Sohraby, M., Shahlari, N., & Hamidpour, R. (2015). Chemistry, pharmacology and medicinal property of Rhodiola rosea from the selection of traditional applications to the novel phytotherapy for the prevention and treatment of serious diseases. International Journal of Case Reports and Images (IJCRI), 6(10), 661-671.
  13. Antonio, J., Colker, C. M., Torina, G. C., Shi, Q., Brink, W., & Kaiman, D. (1999). Effects of a standardized guggulsterone phosphate supplement on body composition in overweight adults: a pilot study. Current therapeutic research, 60(4), 220-227.
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