T Nation

How Quickly Does T3 Shut Down Natural Production?


Bill Roberts says that using 15mcg of T3 per day for up to 8 weeks probably never shuts down our thyroid and still helps to speed fat loss.

I've got access to some LIQUID T3, and from what I've been reading, no matter how good the source, using the liquid form is a crap shoot, with the potency ranging from nil to what's on the bottle.

I thought of ramping it fast to say 75mcg a day, just to see if I "feel the potency", and then staying at what I think is the 15mcg mark. I fear too much permanent side effects such a less performing thyroid forever after to use the "normal" BB doses.

But I wonder how quickly using T3 shuts down natural production. Maybe using only 15mcg doesn't shut us down, but maybe it doesn't let the thyroid "come back" either if we have previously shut it down.

Any thoughts?


Do some more research into this. They treat both groups of people, hypo and hyper thyroidal people with thyroid hormones (some times T3 and T4, sometimes just T4, and some times just T3)

Unless someone on here can access/refer us to studies regarding healthy people using T3; a lot of what you here will be anecdotal and subjective. When I put my hundreds of hours of research into learning about steroids and other ergogenic aids I picked up on the thyroid as being sensitive, once you shut it down it begins to atrophy. If it shrinks enough(too much) it will take a long time to start producing 'normally' as well as to regain it's lost size; some times up to a year or MORE.

On the other hand, a bodybuilding guru at my gym feels comfortable about the use of T3, as do a lot of other people on here.

I personally don't see a problem with using such a small amount T3, but I am not you, and I wouldn't use that small of an amount.

I would probably use it in larger doses for short durations (3 weeks), as well as with a diet geared towards utilizing the state your body will be in from the higher doses of T3. I would also probably use 400-500mgs of test cyp and a moderate to larger dose of masteron... Or 800mgs of EQ and masteron per week. (a no test cycle anyone?)



Anecdotal and subjective stories are basically all we have. I see very few if any posters talk about their nightmarish side effects, yet most of us, with reason, are very cautious, well maybe not enough :slight_smile: Even a slightly less performing thyroid for months would suck big time.

That's why the 15mcg a day proposed by Bill Roberts looks nice from the outside. Just a slight edge to burst through fat loss plateaus, yet not enough to shut it down. By the same token, doing TRT doses vs 1g a week don't produce the same results... It's just that with roids we "know" almost everyone will bounce back. With T3, it's still somewhat of a guess.


Why not go for it and get lab tests before and afterwards...? Feel like being a guinea pig...?


On the theory of ramping up a liquid product of unknown potency:

The problem here is that it is hard or perhaps impossible to judge by feel the effect of low dose T3, and the point which the dosage appears obviously high won't be precise.

Where your method could work I think is that if you perceived a supposed 75 mg/day dosage to feel pretty strong, then the product probably is at or fairly near full potency.

But the reverse wouldn't necessarily be true: it could be that an individual might think that to not feel like a high dose, yet the product might be at full or fairly near full potency.


Im aware that T3 is a popular compound, and is needed with many protocols such as when using GH or some insulin combos...

But for the average user, avoid it like the plague, its playing with fire.

I would never use T3 as a research chemical.

I would be much more comfortable with ECA or even lower doses of clen.


Westclock, I know you really dislike T3. Any specific reason(s)?


Yeah I thought that it could hard to gauge by "feel", even more so if it were the 1st time.

I wondered if after 5-10 days of ramping up, the normal production is already shut down. A bit like with AAS, if you're shut down, might as well take a "real dose". If it's not, than the 15mcg/day might be a better idea.