Cytomel (T3)

This product (Liothyronine Sodium) is sold under different names:

T3
Thyroxyl (T3)

Cytomel is a synthetic T3 hormone. As you may already know, most natural T3 is not produced directly by your thyroid gland, but rather is converted from the T4 thyroid hormone. (8)

Natural T3 is a regulator of the oxidative metabolism of energy producing substrates (food or stored substrates like fat, muscle, and glycogen) by the mitochondria. The mitochondria, as you will recall from your high school biology class, are usually referred to as the “cells powerhouses” because they produce ATP. Taking Cytomel (supplemental T3) greatly increases the uptake of nutrients into the mitochondria and also their oxidation rate (i.e. the rate at which they are burned for energy), by increasing the activities of the enzymes involved in the oxidative metabolic pathway. Everything is working harder, in other words, and more fuel is needed to supplement this increased work rate. Therefore, as you can guess, taking supplemental Cytomel will increase your bodys energy demands. And if you are in a hypocaloric state, you will begin burning even fatter primarily due to an increase in ATP. This increased ATP causes an increase in overall metabolic activity. (8)(9)This is exactly what we want, and is why we would be taking thyroid hormones like Cytomel in the first place. If you arent taking anabolic steroids with your Cytomel, however, your body may start to eat away muscle to provide energy for you to function. Remember mitochondria/ATP arent very picky, but they are very efficient. What I mean by this is that they will use whatever is on hand to generate energy for your body to continue functioning, fat, protein, glucose; it doesnt matter to ATP, as long as theres something to give them energy. Taking this drug will increase their need to find something to burn to create this energy. Ergo, if we arent taking anabolic steroids while taking our T3, we may lose too much muscle, especially while dieting.

See also about Cytomel Side Effects

Thus we can see that there are many advantages to using Cytomel to optimize our metabolic rate. It will also increase your bodys ability to synthesize protein, but from what Ive seen personally, it acts as a catabolic when it isnt administered with anabolic steroids. It is often the last thing added into a precontest diet, as it has a reputation for getting rid of the last few percentages of bodyfat& the “sticky fat” as its called in bodybuilding, the fat that just doesnt want to leave you in the last few weeks of dieting. I think this is a poor use for this drug, and that it should be the first thing added into a diet to lose fat, as it will optimize your metabolic rate, which should be done at the outset of a diet, not after the calorie restriction has diminished your thyroid output and you are adding it in simply to replace what was lost.