I'm in the process of building one. Getting as many calories as possible in the lightest food possible is important and I'm on a quest to find out what the best choices are.
This will be for common store-bought foods, the foods found at almost all resupplies (gas stations, grocery stores, etc.).
Only have Little Debbies done so far but will be adding others as I gather the information. I thought some other people might use the information, so I'm sharing it.
Knorr, candy bars, peanut butters, nuts, Hostess and Pop Tarts are future plans. Feel free to suggest something you'd like to see, if you're into this at all.
Best Little Debbies
Peanut Butter Crunch
Chocolate Iced Honey Buns
Link to spreadsheet