Yesterday I went on my longest trek yet. 130km comprising of 120km of fast road riding and 10km (took 2 hours for this alone) of really steep single track mtb trail. I rode out, hit the track, had lunch, and then rode back. Left home about 5am, got back around lunch time. Plenty of stops along the way to refill my water bottle etc. I rode 30-35km/h on the road and never let me speed drop below 30 unless a hill proved to be too difficult. Even then I never let it drop under 20km/h.
What surprised me was the sheer amount of food and water I went through. I had 4 liters weak Pokari sweat (Japanese electrolite replacement not much energy in it), some fruit, some sandwitches, and some rice crackers. Went through all of that and was still hungry most of the day after that. Is it normal to require so much energy?