I like to run early to get the metabolism going, burn a little fat, and it just generally wakes me up for the day. I've been doing it for a while and I've lost fat and improved my wind for short term endurance, which is my goal. I like the results overall, and I've managed to maintain my overall weight. My real training is in the afternoon.
What has worried me is the other people I pass on the run (I assume running fasted as it is 7 AM) look emaciated as hell.