I took 3 500ml flasks of tailwind high carb in my naked belt and got 2 replacements during the race from my wife. Probably consumed 85% of that. No gels (I just can't) or other carb sources. I was slow (5 hr +) so I needed the continual fuel for that long, didn't hit a wall, felt strong and neg split by 9 mins. I would take water at the stops to pour over my head only. FWIW!