For a day, I don't take any food with me, but do have the ability to gather food if it turns into more than a day. For 2-3 days afield I take parched corn ground into a coarse flour/meal and sometimes mixed with buffalo jerkey on longer outings (Indian trail mix), turkey jerkey, modern trail mix and raw honey which is a rich source of nutrients and fast burning carbs as well as doubling as a good wound dressing as bacteria can't live in honey. Along with the bits of food, I add salt, pepper, cayenne, onion powder and garlic, just in case I get lucky. Because if I am out for that long, I have my weapon of choice and am hunting small game or birds.
I have a variety of cases, bags and rucks that I use to carry my gear. It just depends on where I am going, my purpose for the outing and how long I'll be gone, as to which one I carry with me.
All life is subject to the laws of Nature, or to be more precise, the laws of our CREATOR.