Its not that you are burning more cals while doing cardio on an empty stomach, its the fact that your glucose levels are in a depleted state therefore your body will begin to burn fat faster, where you will burn glucose off first before fat when your glucose levels are at a more normal range or higher. I am a big fan of ephedrine and caffeine, have been for years now, I feel that it works better for me than clen does, although I will throw clen in the mix for a couple weeks here and there while cutting to give my body a little switch to throw it off a little. T3 is a very tricky drug that I can go on about for while, but you only will benefit from it when your T3 levels are lowered from a strict diet, so you need to really know what your natural levels of T3 are at before using. The other thing is the capability that it has to burn muscle as well as fat so you need to know how to use it and the proper dose. I try to only use if for a short period if I need it, but I have gotten the same results with just diet alone, it jsut might take an extra week or 2.