There is a study out that suggests you should eat breakfast before working out. I have always been told to not work out on a full stomach because you could get light headed or sick but the reason for this is different.
The theory: Your body's go-to source of fuel is carbs. If you don't provide it with that fuel, but still force it to move, it has no choice but to turn to plan B: Burning body fat to fuel the muscles and every other physiological system.
Kind of interesting huh? Even if you can't work out the morning, eat something that is good for you and filled of carbs!