Now that this thread has drifted more to the "what do you eat when training, and how often," I guess I'll throw in my two cents. It took LOTS of experimenting, but I find I do well with approximately 100 calories per hour, running or cycling. More than that and I get digestive troubles.

Everyone is different, but for me, when running I don't take anything in (calories or water) for anything less than an hour, or 8 miles. I take in a Hammer Gel and approx. 10-12 oz. of water for every hour over an hour, in approximately 20 minute feeds. I like to carry the gel in a flask and water separately so that I can quit taking in calories if my tummy starts feeling upset.

For cycing, I use Perpetuem (for some reason, I do really well with it cycling, but it give me the runs when running!). For a 4-5 hour hilly ride I'll mix two 24 oz. bottles with 1-2 scoops Perpetuem in each. If it's really hot I'll refill one of the bottles with plain water and drink some or all of that as well.

Like others have said, experiment and see what works for you.