A caveat: such rations are also extremely high in salt since they're intended for soldiers doing heavy physical exertion and because it helps with shelf life.
This is true, you will also be constipated and have an epic time on the toilet. MREs are designed for people in survival conditions and if you aren't, it'll be a fun ride. But they are the most calorie dense way to store ready to go food for an unknown situation, if that's what you need.
