can't give you a solid answer on comparing T3 to clen because I haven't used it. Used clen, eca, and albuterol and like the last two very much. But I am weary to run a synthetic thyroid medication for fear of permanent damage. Your thyroid gland controls numerous functions in the body and forcing it to go into synthetic overdrive can have side effects on a healthy user who shouldn't have taken it in the first place. Hypothyroidism is no joke. My 2 cents. I would look else where for fat loss before t3/4 drugs