I did a solo 24 hr ride (326 miles, 10,000 calories) and I think I ate a little bit of everything that's been mentioned so far: Clif bars, fig newtons, gel packs, PB&J, bananas, 2+? gallons of Gatorade, chocolate milk, coffee, salt capsules, and several hits of ibuprofen. I stayed away from meat, and slowly digested foods.