Choose foods with a minimum of water. For your chocolate fix, bake a chocolate cake rather than packing chocolate bars. Carry dried fruits and Jerkey. Choose foods with a high calorie content. Choose fats like peanut butter over sugar, protein or carbohydrate.
Nuts are preferable as snacks to candy.
Food Systems Pack simple foods that can be combined into many different meals. My favorite is tortillas, rice and several bean powders. A number of meals can be made with these staples. Pack in bulk, not by meal. Depending on a lot of things, your appetite will vary.