Yeah, I agree with Rainbow and Doshkel about eating more in general, but I'm with Kiz too. You want to eat a bit more in general and also have food on you. I used to bike 24 miles a day (to school and back, a rolling hill route - wish I was still in such good shape!), and I really needed both a sports drink and plenty of food on me. I think I ate about once an hour during that time, stuff like peanut butter sandwiches, clif bars, fruit, etc. So I'd bike the 12 miles in, eat when I got to school and eat pretty much on the hour during school, get back on the bike and go home and have a snack sometime during that ride too. (This was also in summer, and the sports drink gets REALLY important then.) Good luck - biking is a GREAT method of transportation! Environmentally friendly, cheap AND good for you!