How long can one live off of military rations? Or premade civilian foods?

I guess technically you could live off MRE’s indefinitely. Same with civilian premade food. Most of it is just dried food. The problem with dried food is that if often loses some of its nutritional value because you dry out the good stuff. If you really are considering long term storage food, I would suggest investing in a really good dehydrator and doing it yourself. I own an Excalibur dehydrator…the cadillac of dehydrators. Dried food nutritional value depends greatly on how you dry the food. For instance, I just made kale chips in my dehydrator. I could have done them in a couple hours at a higher temp, but that cooks off a lot of the nutrition. But I get to control it so I dry it at a lower temp for a longer period and maintain some of the good stuff. We made a stew for camping one time. Dried veggies, mushrooms, herbs and some beef bullion cubes into a jar. Took it camping, put it into a big pot, added water and cooked it over the fire. Fed 10 people and the leftovers fit back into the jar. But if food is dried sufficiently, as most MREs and civilian premades are, and if they are stored correctly, they can be good for 25 years or so.
As for is it less unhealthy than take out? I guess it depends on the take out. If you are talking about wings or pizza, yes, they are. If you are talking about having a big salad delivered, no they would probably not be as good as that. The big difference is the taste. You would have to cook (rehydrate) most of the premades and they might be a little bland. On the other hand, the take out might be wonderfully tasty. And you wouldn’t have to cook it.

Our survival stores have their own MRE’s & dried foods which include fruits, beans etc…all really tasty. I didnt check nutritional value but I will next time, good question.

BTW, I make killer beef jerky in my dehydrator too!

There are billions of people who live off of far less…

Anecdotal evidence suggests that a regular diet of MRE’s are constipating and that the constipation does not end well; usually a massive blowout is the aftermath. I am thinking that if you don’t mind going through this on a regular basis then it should be ok. But, also keep in mind that MRE’s are usually high in fat, carbs and calories, the idea being that you will be burning it off anyway with activity and need the energy boost.

Note: they may have reworked the MRE’s to make them less constipating but the couple of folks I spoke to who were in Iraq 10 years ago say that they were still giving problems.