I don't count calories, I go for ' easy' food, that is fairly easy to prepare. I bring some macaroni, a smoked sausage or some sort of salami and a packet of powdered sauce. A small can of Spam is great too. Just add the contents to taste in a pot with enough water, boil and eat. Not too much water, so you don't have to drain it. A bit soupy is nice. (I find that when walking I need all the water I can get).
The Bachelor pasta 'n Sauce may not be everybody's favourite but when I'm hungry it's delicious. Instant noodles are tasty as well.
Intant mashed potatoes and sausage are nice, couscous and spices are easy and all quick to prepare without using too much fuel.In between of course there's chocolate in all different sorts, or nuts / trail mix. A packet of biscuits (McVities chocolate covered digestives!!) offers great psychological benefits as well.
When I've been out for four or five days I always expect to have lost weight but when I step on the scales at home there is hardly any significant loss: apparently I take in enough calories.Pricewise this is an economic solution. All available from your local supermarket, prepacked at home in the sizes/quantities that you require. It doesn't have " Outdoor" or " Adventure" stamped on it and that reduces the price by about 90%.