Taters & Pork

Start with some dried potato powder and all the seasonings you can stand. Preferably repackaged in a freezer bag with content and calories labeled...

Set up your stove. Add 1 oz of fuel.

Light stove.

Stare in awe at the pretty fire.

Bring two cups of water to a boil.

Once boiling, pour water into bag.
Knead bag.

Since you need the calories, drop in some sort of meat. Here we have a Spam single.
Crazy Tasty!

Break up the meaty product while continuing to knead bag.

Dinner is served!

Eat your dinner, reseal the bag, and start walking again. You're being fueled by 610 calories. And remember, you can add 120 calories per tablespoon of oil you drop in there!