I do take some BCAAs before my fasted cardio. I like the fasted cardio. It has worked well for me and I feel like I am retaining muscle very well. I might try switching up the cardio though because it will be very hard for me to do cardio in the morning if I need to wait an hour or two after taking my clen.well i would wait at least an hour, 2 if you can. I am not sure how good an idea fasted cardio would be once again, at least try to have an iso-protein shake or BCAAs.