U.S. Army Wants to Learn How Military Rations Affect Gut Health

Digestive health is really getting its place in the spotlight these days, with new findings constantly being released on the importance of the bacteria in our guts and how that bacteria impacts other bodily functions and organs (even our brains!). And it’s no secret that what you eat has a profound impact on the kinds, and health, of bacteria living in the gut.
That’s why the U.S. Army Institute of Environmental Medicine is investigating how military food rations called MREs, or “Meals, Ready-to-Eat,” affect gut health — and are recruiting volunteers for a 21-day study.
In the study, participants (who must be between ages 18 and 62, and will receive $200 in compensation) will either eat their own normal diet for 31 days, or eat nothing but MREs for 21 days. Over the study period, participants will also have to give blood, urine, and fecal samples.

MREs originated during World War II, and includes an entree (like spaghetti or beef stew), a side dish (like mashed potatoes or corn), crackers or bread, some kind of spread (like peanut butter or a cheese spread), dessert (like cookies), candy (like M&Ms) a drink (like coffee or tea or sports-drink-like mixes), and utensils and a flameless ration heater, according to the U.S. Army. Each MRE is meant to provide 1,250 calories, on average, as well as one-third of the Military Recommended Daily Allowance of vitamins and minerals.
https://www.yahoo.com/health/digestive-health-is-really-getting-its-place-in-150912989.html

Many of us took the appraoch that you needed to eat to survive but that's about all you wanted from an MRE. Some entrees are actually not too bad when heated, assuming you didn't make an MRE bomb from the heating packet. There are some good snacks type things, probably the better part of an MRE. Crackers are not quite as good as cardboard though. Drink mixes similar to koolaid are tough to use as you're beaten to death with pure water only in your canteen so there's less opportunity to mix it. It's a common thing to get the powder in your mouth and add water, swish it around and swallow.
I didn't mind MRE's but you didn't want your diet for days and weeks, you didn't want all the calories, I think 1250 is probably a VERY low estimate, if you weren't at a high state of physical activity. Also notorious for constipation which in field ops limiting #2 can be good and bad.