I agree with everyone who said that it depends on body type, and how your body has historically responded to training.

I, for one, am tall/thin and can eat pretty much anything and not gain weight (please don't hate me). I do a huge amount of on the bike training including a mix of long rides (100+ miles) and short intense interval training sessions. During short sessions, I don't eat on the bike and rely on water for hydration. However, I try to eat right after my workout to replenish what fuel I used and to jump-start the recovery process. I am not trying to lose weight, however. Nonetheless, it is important to eat something right after a workout because it really does aid in recovery.

On long rides, I eat bars and gels and drink Gatorade. Even if you are trying to lose weight, it is important to stay on top nutrition on the bike, because if you don't, you run the risk of running out of glycogen stores and bonking - this is serious.

How has my body changed? I have lost some weight even though I try not to. My legs are super toned although not massive (my quads are pretty defined, however). My core is stronger, but my arms are like sticks.

Overall, I feel great. I feel strong and healthy, and this is the most important thing to me!