I'm 48 years old... I don't need to eat during a 50, but everyone is different. You might do diluted juice in one bottle.... start out well hydrated and stop to pee around the 20 mile mark. I predict you'll feel it in your contact points way more than leg fatigue (or any fatigue). Get up out the saddle often and early. Move your hands around on the bars BEFORE they develop issues.

Have fun!