Everything was going to be calculated to the gram, and foods were going to be chosen for their density, aiming for an average of 4.5 calories per gram. Using various calculators, I figured out how many calories each of us would need and planned on packing each person's individual food accordingly. Many websites suggested that it was not a good idea to stop for a big lunch but that it was better to snack all day, a continuous fueling rather than stopping mid-day and being starving before, too full after. I planned what I called a Hobbit diet, from Lord of the Rings; first breakfast, second breakfast, elevenses, first tea, second tea; you eat all day long. I packed the calories into the continuous drip of food throughout the hiking, with about a quarter in breakfast, a quarter in dinner, and half in the snacking throughout the day.
I built a big spreadsheet to calculate it all.
A lot of people hike with dehydrated foods; I have never liked the taste of them. However I discovered a wonderful website, Onepanwonders, and picked a couple of dinners from there. Then it was off to Iceland.