I took this excerpt (left out the part about how he said to maintain a low-fat diet!) from an article on askmen.com by Ian Lee entitled "Fat Burning Morning Workouts." Just adding some more info on the positives of AM cardio on am empty stomach!

Now, here's why cardio training in the morning is a great way to blast fat:
Your levels of muscle and liver glycogen (also called stored carbohydrates) are normally very low when you wake up first thing in the morning. With depleted glycogen and lower blood sugar, you'll give your body the perfect environment to burn fat instead of carbohydrates.

Carbohydrates or glycogen are your body's primary and preferred source of energy. When they're low, your body will tap into your secondary energy reserve, which is your body fat. The idea here is similar to when the engine taps into the car's reserve tank because it's low on fuel.

Obviously, your body is way more complex than your car's gas tank. It always burns up a combination of carbohydrates and fat. However, the less carbohydrates you have, the more fat your body will burn.

Are you convinced yet? If so, great -- but expect an adjustment period. The same way you're jet-lagged after an overseas trip or drowsy when you suddenly have to switch from the graveyard shift to a regular 9 to 5 shift, training in the morning will require some lag time.

Normally, it should take approximately three weeks for your body to fully adjust to the time change. You'll start feeling fully energized; you'll wake up more easily and will generally be more alert.

Now all you need is a louder alarm clock to help you get up those first few weeks. Before you know it, you'll be a lean, mean, morning machine. Good luck and keep on pumpin'.