T3 derivatives: T2 & T4 fat-burners
3,5-Diiodothyronine
3,5-Diiodothyronine, also known as T2, 3,5-T2 or 3,5-Diiodo-LThyronine, is a metabolite of T3. On a mcg-to-mcg basis, T2 is much weaker than T3, but studies have shown that T3 can be highly effective at burning fat by accelerating metabolism, stimulating mitochondrial function, and increasing lipid mobilization.
Even though there is very little scientific or anecdotal information about the effects of T2 in humans, it seems to provide many of the benefits of T3 without being as catabolic or as suppressive of TSH levels. Most users who have tried both T3 and T2 do think that T3 is more powerful, but many of them believe that T2 offers a better risk- benefit ratio.
A typical T2 protocol would consist in taking 150mcg a day for a couple of weeks, followed by 200mcg a day for two more weeks, then 250mcg a day for another two weeks and finally 300mcg a day for the last two weeks.
Even though the side-effects of T2 may be less pronounced than the side-effects of T3, it will still cause the same negative symptoms and it will suppress TSH to some extent, meaning that your thyroid function will be suboptimal for a week or two after ceasing T2 use.
Levothyroxine
T4, also known as Thyroxine, is a thyroid hormone that acts as a precursor to T3. TSH stimulates the thyroid gland to produce T4 and T3 at a ratio of up to 14:1, but approximately 40% of T4 later converts into T3.
The synthetic form of T4 which people with thyroid conditions and bodybuilders take is called Levothyroxine (also known as L-Thyroxine, Synthroid and Levoxyl).
T4 is much weaker than T3, and even though it can be taken on its own, it is often stacked with T3 so as to simulate the natural secretion of thyroid hormones. Generally-speaking, the benefits and side-effects of T4 are the same as T3, except they tend to be milder.
When taking T4 on its own, a good rule of thumb is to take 2x to 3x the amount of T3 we would be using. So starting at 50 to 75mcg a day and working our way up to 150 to 200mcg a day over the span of 8 weeks.
When stacking T4 with T3, most people opt for taking them at a ratio of 2:1. So 50mcg of T4 + 25mcg of T3 a day for the first couple of weeks and working up to 100mcg of T4 + 50mcg of T3 a day by the end of the 8-week cycle.
T4 on its own is not as suppressive of TSH as T3 is, but it will still cause hypothyroidism for a week or two after coming off so be weary of your calorie intake during that time.
Is T3 too strong for your needs? T2 and T4 offer most of the same benefits without being as hard on your heart, TSH production and muscle mass. Still, be sure to take the right precautions when using them to ensure you get the best possible results without altering your metabolic function in a negative way.
