You will be missing out on local cuisine and specials if you eat the same thing all the time on a tour: B-o-r-i-n-g!!!!
Go with the flow; drink before you're thirsty, eat before you're hungry. Yes we do carry extra food/water, just in case.

On a 500 mile tour in 6 days with 22,000+ ft. of climbing on our tandem, my stoker Kay put on 5 pounds by the end of the trip!
We rode from the south rim of the Grand Canyon to Mexico (no, it's not all downhill as some folks surmise) and is a real workout.
The next time we did that tour she watched what she ate (no bakery stops) and managed to gain only 3 lbs.
Temp/terrain/distance/fitness level will also dictate food intake;
She would eat a big breakfast, a small lunch and dinner (some kinda salad) with food/fruit snax in between.
We do not do energy bars or drinks.
She was so used to riding 200 miles a week that a 500 mile tour was no big deal.
Some great local foods will be missed if you stick to a rigid/boring diet. Fresh smoked herring near Duluth, MN; Kolaches (Czech pastries) in La Grange, TX;
Pasties in northern MI and WI; great brats in WI and MN; fresh local cheeses and super ice cream in Logan, UT, etc.
Amazing what your body can/will burn for energy.
Yummmm!
Pedal on TWOgether!
Rudy and Kay/zonatandem