Years of running and cycling I have trained myself that I basically need no nutrition for 60 miles as long as I eat well the night before and replenished the glycogen stores in muscles. I can get by with one bottle of water 27 oz. not an issue unless in the midday heat I normally ride very early mornings. For a century or even if I was trying to race a metric century I need fuel for performance. For a century I go with a peanut butter and jelly sandwich and fig newtons. Another good once simply keebler butter crackers I love them and they have salt so that I keep drinking. Maybe about 500-700 calories pushing a century.
However when I am done look out................beer, ice cream and anything that is not nailed down.