the whole point of fasted cardio is to burn up your body's energy stores (fat) instead of the fuel you put into your tank (carbs).
do morning fasted cardio, down some BCAA's (XTEND or PURPLE WRAATH) before and during your session to prevent catabolism (muscle breakdown).
keep your intensity low to moderate (walking, lite jog, incline treadmill at a moderate pace, stationary bike, etc). to be sure your intensity isnt too high, find out what your optimal heart rate would be.
take 220 - (your age) =(max heart rate). usually between 40-50% of your max heart rate is where your body is usually almost primariy fat for energy.
or you could have a scoop of whey maybe 30 mins before your am cardio. ive had success with both whey before and bcaas pre/intra cardio.
good luck brotha!