Cytomel T3 does speed fat loss. As a guideline for most 12.5 mcg/day is a conservative sort of dosing that seems to have no detectable adverse effect on thyroid function at all. 25mcg per day is a “supplement” sort of dosing that does have some inhibitory effect. 50mcg per day is a reasonably conservative bodybuilding sort of dose that, of course, is more inhibitory. 75mcg per day is getting into more of a problem area; 100 mcg/day in many cases leads to loss of muscle size and strength.