It's why I keep a few Gu Gels with me whenever I ride. Most of my weekday rides start as little as half a hour after I drag myself out of bed, which leaves scant time for pre-ride eating. Often I chow down a banana, go riding, and have something more to eat when I get back home.
But a banana isn't all that much fuel, especially when I ride hard. It isn't unusual for me to start feeling hungry before I get back home. I'd be a lot more worried that I'd bonk if it weren't for the "security blanket" of those GUs!
It would be so nice if I could eat a proper breakfast and have a hour or two to let it settle, then ride; but I'm not about to get up at 3 am!