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.