T2 Thyroid hormone: Can this be a promising answer to increase metabolism and weight loss?

Ever heard of the T2 thyroid hormone? You’ve likely heard of TSH, T4, and T3... but what is T2? Possibly another hormone to consider when looking at thyroid health. T4 (Thyroxine) and T3 (Triiodothyronine) are your main thyroid hormones.

While both play a major role in your body's metabolism, helping support brain function, digestion, energy metabolism, and more bodily processes, you may not want to neglect your other thyroid hormones. In fact, you also have T1 thyroid hormone.

Wonder why you’ve never had these hormones tested?

Well, the short answer is that both T1 and T2 thyroid hormone behaves as precursors/byproduct of your T4 and T3 hormones. What do all of these hormones (T1, T2, T3, and T4) have in common? Well, they are all made up of a protein known as thyroglobulin.

While it's been believed that T2 is a byproduct of your more active thyroid hormones (T4 and T3), there is some evidence that your thyroid actually produces T2. Not to complicate things even more, there are several forms of T2 that need to be explained.

It is generally considered that T2 is inactive, but this is too general of a statement, given that there are different forms of T2. In fact, one form of T2, 3,5-Diiodothyronine has been shown to play some interesting roles when it comes to the thyroid and metabolic function.

In fact, in rodent models, 3,5-T2 was administered, and it was found to rapidly increase not only the subjects’ resting metabolic rate, but also showed beneficial hypolipidemic effects. What does this mean?

Well, this research is indicating that 3,5-T2  may play a significant role in enhancing weight and fat loss by increasing how many calories the body burns at rest. This information is something to consider in patients with hypothyroidism or hypothyroid symptoms. 

T2 and cholesterol 

The thyroid function plays a large role in cholesterol metabolism. Very often we see patients with hypothyroidism struggling with metabolic function, like breaking down and processing cholesterol. Oftentimes, we see patients with untreated hypothyroidism have elevated levels of cholesterol. It has been assumed that its the role of active T3 that primarily helps with metabolizing cholesterol; however, T2 may be playing a significant role in cholesterol metabolism.

There were rat studies done that showed short-term administration of 3,5-L diiodothyronine (T2) to hypothyroid rats that showed increased mitochondrial function by increasing ATP activity. What does this mean? ATP, also known as Adenosine triphosphate, is the energy-carrying molecule in your cells.

When your cells are functioning optimally, you’re better able to metabolize and have increased efficiency in losing weight. That T2 has been shown to play a significant role when it comes to energy metabolism and the proper breakdown of cholesterol.

T2... what are the benefits?

A lot of the research has been done on T2; however, most has been done primarily on animals. There has been a study on human subjects, though, who were supplemented with T2 with no other changes made to their thyroid medication. After slightly less than one month, there was a noted average weight loss of 9 pounds. 

While many studies on human subjects have not been done, this one study shows promising evidence that T2 can be very impactful in hypothyroid patients (specifically those experiencing metabolic issues). In fact, T2 has been found to active brown fat.

Brown fat is a special type of fat that produces heat and allows your body to burn more fat. So not only has T2 been shown to increase fat metabolism, help your body better process, and in effect, lower cholesterol, but its also been shown to potentially help stabilize blood sugar and maintain muscle mass. 

So how do you get T2?

The thyroid gland naturally makes T2, so you can find it in naturally desiccated thyroid. It's unclear the exact amount of T2 in naturally desiccated thyroid (NDT), however, we expect the amount to be consistent given that it's been standardized in the amount of T4 and T3.

This is derived from the thyroid of a pig, so unfortunately, if you have dietary restrictions or follow a vegan or vegetarian diet, it may not be the best option for you. However, suppose you feel like you’ve been on thyroid medication and still struggle with your metabolic rate and ability to lose weight. In that case, naturally desiccated thyroid may be a medication to consider. You should speak to your provider and see if this may be the right medication for you. 

What does this mean for me?

As we have been able to note from the research, there is a lot of evidence that points to the possible effects that T2 has, and that is not merely an inactivate byproduct of T4 and T3 metabolism. We see, based on animal and even human studies, that T2 can play a major role when it comes to increasing metabolic rate, lowering cholesterol, enhancing mitochondrial function, and aiding in significant weight and fat loss.

Obtaining standardized T2 in the marketplace is currently limited to natural desiccated thyroid (NDT) that will provide you with T2, T3, and T4 from the thyroid of a pig. While the T2 is not entirely standardized from our knowledge, it is consistent from pig to pig.

Based on the research, it seems there is still a significant amount of information to be learned when it comes to thyroid function. As Naturopathic Doctors, we don’t merely assess your TSH (thyroid stimulating hormone) to assess thyroid function. We look at your Free T3, Free T4 thyroid antibodies (TPO, thyroglobulin antibody, TSI), as well as your nutrient status in its role in your thyroid function.

As we see, there may be more pieces of the puzzle to assess when it comes to your thyroid function and the specific role each of your thyroid hormones places. This is promising to many individuals with hypothyroidism who seem to have “normal” thyroid levels but still exhibit significant thyroid symptoms.