Sure you can use them. For hardcore diets, alot of people rotate clen/ECA two weeks on and off, and run T3 for 6 weeks ramping up and down. It's what I'm doing actually, except i'm not using clen b/c I'm immune to it. I'm trying to find a substitute, but right now I just use Cardio Breeze for 2 weeks then 2 weeks off.