What The Wogster is talking about is dead on. You don't want to get your blood sugar way up, because after that comes the WAY down. I rode my first century when I was still close to 300 lbs. I took along two peanut butter sandwiches on whole wheat that I cut into halves, some lightly salted peanuts, a Clif Bar or two and a l LOT of water. Every hour or so I would take in a half a sandwich and some water, or a handful of nuts and some water, etc. This kept my blood sugar and energy levels right where they needed to be so that I could do what I needed to do on the bike. For what it's worth, my rides are ALWAYS better when my nutrition is on point.
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"Obstacles don't like me very much. I make them look bad."