Replying to Running on empty

as i was running tonight to get ready for my soccer tryouts, i realized i hadn't eaten anything or drank anything today. but i ran a good 5 miles in less than 35 mintues. so a good pace. is this good for me? i would think it would be unhealthy to run with no water in me or energy in the form of food. yet in a sense could this be good for my conditioning. like i can run 5 miles easy with no energy, so i should be able to run like 10 miles easy when i'm actually rested, have fluids in me, and food in my belly.