Ive recently started (and by recently I mean this week lol) working out again.
I asked a smiliar question to a friend who trains for hockey constantly and he said its better to have somthing in you. Doesnt have to be a huge meal or anything but it wont help if you have an empty gut.
I believe it has to do with your body using what you have eaten for energy vs using what is already in your body. If you supply your body with the energy by eating first, it is likely, that is what you will use first.
I wouldn't recommend it.. it would have to be done in the morning (unless you don't eat half of the day, which I hope you don't), and since your body is in catabolic state when you wake up, it'll be detrimental to your muscle. You want to replenish your muscle glycogen stores before doing cardio with a light protein shake and some amino acids (BCAA typically) mixed in it. Then go do your cardio 20 min. later