i second that. something small/sweet (hot drink, coffee or something) 10 kms is alright to do with no food in yr belly tho. and there were some people who talked about how training on an empty stomach can be good for fat burning.

word of caution though, i used to ride 7km to work daily on an empty stomach and that was fine. but one morning i did a training ride in the morning before having anything. i think i rode 15km, fast one. I got back, decided to shower before eating something, and i almost passed out in the shower cubicle... that was a scary one. fortunately my roommate was around to hand me a sweet drink that was sitting on my desk.