t3 is actually anabolic - if you supply yourself with enough calories
it speeds up all your processes, including protein synthesis
the problem is when you're using either a high high dose or not getting enough calories and adequate protein
author l rea recommends 25-50mcg/day + 2g protein/lb for the anabolic effect (of course he also recommends stacking it with hgh, insulin, and 100mg test prop/day)
My personal experience is that it was VERY anabolic at about 30mcg day - you don't get the rapid strength build up of steroids, but your body functions are all faster and you can build muscle much quicker
I found that above 50mcg/day it didn't matter what I ate - fat just melted off
and around 100mcg/day, I experienced serious catabolism
a lot of people will tell you that its a harsher/more serious chemical than clenbuterol (the other popular cutting steroid) but I find next to no side effects with t3 - just a dry mouth - and if you taper up and then back down you should be fine.
There's a lot of rumor about how t3 will shut off your thyroid but I have yet to see anybody actually do so, and I've known people running it at 125 mcg/day for 4 weeks.
To be safe, run 3 weeks on, 3 weeks off, don't exceed 100 mcg