What Happens When You Eat Nothing but MREs

C. Davis
By C. Davis November 16, 2017 13:04

What Happens When You Eat Nothing but MREs

By Claude Davis

Ah, MREs. Meals Rejected by Ethiopians. Meals Rejected by the Enemy. Meals Rejected by Everyone. It actually stands for Meals, Ready to Eat, which has been described as “Three lies for the price of one” – it’s not a meal, it’s not ready and you can’t eat it.

Of course, soldiers love to complain about their rations, and the truth is that MREs aren’t too bad. Some of the menu items are real horrors, but most are reasonably edible and nothing’s as bad as the old C-Ration ham and lima beans. There’s plenty of energy in MREs, too. Overall they’re a pretty good combat ration.

The same things that make them a good combat ration also make them popular with preppers. MREs are sturdy, energy-dense, can be eaten without preparation and have a long shelf life. If you’re looking for an emergency food reserve they’re an obvious choice. However, don’t rush out to buy a year’s supply of them just yet.

MREs were never designed to be your only food source for long periods of time. The US Army tries to give troops in the field properly cooked food wherever possible. Even infantry in forward positions will often get containers of hot food delivered. If you’re deployed to Afghanistan and spending a year in a Forward Operating Base, you won’t be living on MREs unless something’s gone really wrong – the FOB will have a dining facility, with a proper kitchen and a couple of slop jockeys to produce proper meals for everyone. MREs are a tactical ration, and they’re meant to be used when there’s no other food available.

Related: How to Make Delicious MREs at Home

How Long Can You Eat Them For?

According to the Army, MREs are meant to be used for up to 21 days – and, even then, they’ll usually be supplemented with fresh rations. If the logistics system is running smoothly it would be very unusual for troops to eat nothing but MREs for three weeks. They’re a high-energy food source, and prioritize caloric content and essential short-term nutrients over a real balanced diet. They’re also designed for long shelf life and easy preparation, and that has some consequences.

The human digestive system is a pretty complicated thing and, as anyone who’s eaten street food in Afghanistan knows, it isn’t hard to upset its delicate balance. As well as your own organs, enzymes and stomach acids, healthy digestion relies heavily on your gut flora. This is what biologists call the collection of bacteria that live in your innards and pay for their lodgings by helping you process your food. If these bacteria aren’t feeling too well, you won’t be either.

MRES Lima BeansNow imagine you start eating nothing but MREs. Suddenly, your entire diet is nothing but highly processed food that was designed to have a long shelf life in a variety of harsh conditions. People sometimes compare MREs to junk food, but that doesn’t even begin to describe how processed they are. MREs can sit on shelves in a warehouse for years, or spend months in a humid, baking container under the desert sun, and they’ll still be edible when they finally get handed over to some lucky soldier. That isn’t how food usually works.

To achieve this shelf life MREs are cooked a lot more thoroughly than most food. They also have preservatives added to prevent bacteria growing inside the pouches, which would spoil the food and probably poison the soldier. What effect do you think all those preservatives are going to have on your gut flora? Sure, most of us eat foods that contain preservatives every day, but what if that’s all you eat? Your poor gut bacteria don’t stand a chance, and after a week or two they’ll start dying off.

When the gut flora starts to die, the usual result is diarrhea or constipation. The Army knew this from the start, but decided it wasn’t a big deal. MREs might be high in preservatives, but they’re very low in dietary fiber, and a low-fiber diet causes constipation. In fact the fiber content is so low that the crackers and bread are pretty much the only significant sources of it. That’s why soldiers who start eating MREs usually find they’re bunged up for a few days, and then things seem to settle down. People generally think their bodies are adjusting to the diet, but that isn’t exactly true. What’s really happening is that two effects of MREs – diarrhea and constipation – are fighting a war in your digestive system, but neither of them is quite strong enough to win it. Try living on MREs for a week, then stop eating the crackers and see what happens.

Related: The Best ORAC Foods to Stockpile

Nutritious or Nasty?

The longer you live on MREs, the worse state your gut flora will be in. That’s why the Army aims for a 21-day limit. Even after that length of time, you’re likely to suffer some digestive problems when you move back onto more normal food. If you ate nothing but MREs for three months you’d probably be pretty ill for a few days when you started eating properly again. It’s hard to completely kill off your gut flora, but after three months of getting all your food from brown plastic bags it would be in a very bad way.

As well as their effects on your digestive system there are some other reasons why eating MREs for long periods isn’t a great idea. Their low fiber content can cause a wide range of health problems. Most of these are digestive issues, but low fiber has also been linked with high blood pressure and an increased risk of some cancers, including colon cancer. The sodium content, on the other hand, is pretty high. That’s useful if you’re working hard in the desert and losing a lot of sweat, but under less strenuous conditions it isn’t ideal.

If the only food you have is MREs you can survive on them for a long time – years, probably – but it definitely wouldn’t be good for you. You’d start suffering from the lack of a whole range of nutrients, and some of the consequences can be serious. It’s best to have a stash of MREs to keep you going through the worst initial stage of a crisis, but get back to eating properly as quickly as you can. MREs are pretty good at what they were designed to do, but if you’re eating them for more than a couple of weeks you’re probably going to regret it!

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C. Davis
By C. Davis November 16, 2017 13:04
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  1. Doug November 16, 15:01

    Ahh yes, I remember the filet of green can well. I left active duty before I had a chance to contaminate my intestinal tract with a lot of MRE’s. I had used LRRP’s in the past when I was in a special unit. A good pro-biotic and some fiber pills could help. A huge bottle of Tobasco Sauce works wonders on even the most gruesome of the meals. I remember being at Ft. Bragg, we usually used the fruitcake in C-rations for our own special enjoyment. I buried a bunch of them at Bragg hoping some archeologist would find them a couple of hundred years down the road. Let them try to figure out if it was edible or not.

    Reply to this comment
    • Homesteader November 16, 19:56

      I had C-rats in my early years in the Air Force. Then MREs came along. Those early MREs were like eating salty cardboard compared to the C-rats. A few years ago, I bought some contractor MREs that were only a couple of months old. The contractor they were made for never claimed them. From what I hear, they’re slightly different from regular military ones. I haven’t been able to try one yet. Even though I retired from the AF 26 years ago, the thought of eating another MRE of any kind is still unpalatable.

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    • Hildegard November 18, 06:53

      Mostly Rat Entrails

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  2. Old & Gray November 16, 15:58

    It’s interesting that Mr Davis would promote an article that doesn’t match the photos within it. If you’re going to talk about MREs, why would you include photo’s of “B” and “C” Rations. These rations are much older than MREs and date back as far as WWII and Korean War and used a lot during Vietnam. MREs entered into the picture around 1980s. So if anyone is eating food out of a cardboard box in the photos, those rations are at least 50 years old and unsafe for consumption.

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    • The Flavoured Wurzzel January 30, 13:29

      You didn’t read the article properly.

      “Some of the menu items are real horrors, but most are reasonably edible and nothing’s as bad as the old C-Ration ham and lima beans.”

      Photo in reference to that.

      Reply to this comment
    • Deanis March 21, 09:30

      That looks like one of Steve1989MREInfo’s videos on youtube. He eats rations from 1899 and lives!!

      Reply to this comment
  3. Doc November 16, 16:06

    Useful and enlightening. The topic of GI bacterial flora normally present in a healthy gut has led to probiotics and their use, now backed up by studies designed to tout prebiotics – a method of assuring continuing production of healthy gut bacterial content. Once again the military leads the way at keeping military members functional and also healthy with their studies maintaining a healthy gut bacterial content. Can “ prebiotics “ be an even more complete program for them and eventually spill over to Civilian Medicine? The average American diet most likely is not so friendly I expect to a healthy gut flora.

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  4. JohnBoanerges November 16, 16:08

    MY “MREs” are these Indian meals like produced by Kohinoor and sold in New England at Ocean State Job Lots for $2.00. I have hundreds of them put by and I eat them frequently, too. There are about 10 varieties I collect and are packed full of dietary fiber. I often add a can of sardines and some quinoi, coconut oil, shaved ginger and almond flower and a fresh clove of garlic and other supplements and have a full meal.

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  5. Dennis Simons November 16, 17:36

    Would you rather eat nothing in a time when you have to eat MRE’s

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  6. mcruff November 16, 17:44

    I was in from 82-86 so I started on c-rats and switched to MREs. I actually preferred the c-rats as did a lot of the guys I served with. Finished my time in Korea and did live on MREs for 2 weeks straight while on a training exercise, blah.

    Reply to this comment
    • Nickname944 October 28, 02:15

      Oh thats rough man, 2 weeks on MRE is very…..”interesting”. Did ya get a brisket in gravy one? I did. It is literally dog food, I was so mad. To this day I can still taste it, HHHOOORRRRIIIIBBBBBLLLLEEE!!!! XD

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  7. Teddy November 16, 17:54


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  8. Guitpickin CowHippy November 16, 18:37

    What happens when you eat nothing but MREs for weeks on end is that you (and your entire unit) end up STINKING like MREs. Funky chemical smell, which frighteningly smells exactly like the toilet paper included in the accessory packet. Kind of like a burnt multivitamin.

    A DI once said something to the effect that (pardon the capitals, but it was a DI speaking, after all…) “SHUT UP AND EAT’EM! THE FOOD WE GIVE YOU IS NOT FOR YOU TO ENJOY – IT IS TO KEEP YOU ALIVE LONG ENOUGH FOR YOU TO DIE IN BATTLE DEFENDING YOUR COUNTRY!!!”


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    • Guitpickin CowHippy November 16, 18:40

      Oh, and the brown bag 80s MREs had a lot of beautiful menu items which “they” (Natick?) left out of the khaki MREs…like the freeze dried fruit bricks…but they also had some completely vile items…like Chicken a la King…peas and chicken chunks in an influenza mucus sauce…ew

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  9. left coast chuck November 16, 18:51

    Hey, ham and lima beans was one of my favorites.The one I hated was sausage patties in “gravy”. Even kept inside one’s garments so that it wasn’t a frozen block at body temperature the “gravy” was still mostly congealed grease. When we were on c-rations the Marine Corps tried very hard to get fresh oranges (scurvy) and fresh apples (fiber) to the troops on a regular basis but conditions sometimes precluded that delivery.

    I guess it has been too long, but at one time everyone I knew was aware that after three days of C-rations your intestinal tract slowed down. That was not necessarily a bad thing. There are times when activities around you cause you to not have complete control over your bowel functions. Having a slow bowel is a help. When the daytime temperatures are at best 0°F and at night are considerably lower, relaxing over a slit trench with one’s garments lowered is not an enjoyable experience. So only having to experience that pleasure every three or four days was a blessing. Finally, the beans in the ham and lima beans provided necessary fiber, although at the time we were quite ignorant of that.

    Can’t comment about MREs but they are calorie dense sustenance similar to C-rations, so I suspect the bowel effect is very similar.

    Not to dwell on an unpleasant topic too long, having diarrhea in extremely cold weather is life threatening. The German Army suffered many deadly casualties during the retreat from Moscow from frozen anus. Having diarrhea with lots of clothing on to keep warm means that sometimes one can’t disrobe quickly enough and consequently soils one clothing which then freezes. While it is not talked about too much, we also lost some Marines on the march down from the reservoir from frozen anus. You have your regular underwear which was cotton, you had longjohns on which were a wool blend, you had your regular utility trousers on and if you were lucky, you had a pair of cold weather trousers with suspenders which meant you had to open your cold weather jacket to release the suspenders. On top of your cold weather jacket you had a pack, maybe some bandoleers of ammo and around your waist you had a cartridge belt. Getting all of that off in a bout of diarrhea usually meant that you didn’t get it off in time.

    While most of us will never experience having to live outdoors in extremely cold weather, in an EOTW situation, folks in the northern states or high altitude areas may have to live out doors 24/7. They will quickly find being constipated is not the worst thing.

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    • "Johnny3h November 17, 01:02

      I too LIKED Ham and Lima Beans! Many of the guys would chunk it in the to-be-buried pile; I would ‘rescue’ it, and NEVER went hungry!
      Sometimes, WHEN THEY GOT HUNGRY ENOUGH THEY WOULD BEG ME for a can of Ham and Lima Beans, which I’d sell to them for 5 dollars (my fee for humpin’ all that extra weight for ‘em!!!)

      Reply to this comment
  10. SouthernAZ November 16, 20:25

    The purpose of these is as well stated in previous comments: keep you alive and somewhat alert in combat. They also are designed for low fiber to minimize BM’s in hostile places. Hard to fire your weapon while in the squat. I keep some to use on the move, such as in a get-home bag. My food storage is comprised of only about 5% MRE’s and another 5 to 10% pre-made items like Backpackers Pantry and Mountain House entrees. The remainder is a combo of other relatively real food, canned or otherwise packaged for long term storage

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  11. Dave from San Antonio November 16, 22:34

    I’ll tell you…from my experience in the military. One… you will not get the nutrition you need. Calories, yes, but not nutrition. Two…It will back you up like you never experienced in your life. Drink lots of water if you plan on eating these, exclusively, for more than 3 days.

    Reply to this comment
    • Homesteader November 16, 23:43

      Drinking lots of water cannot be overstated when it comes to MREs. I’ve seen people put in the hospital due to eating them and drinking only a can of soda.

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  12. MedKnight November 17, 00:20

    Ate C-Rations in the service but have had numerous occasions to eat MRE’s more then a few times since. True MRE’s aren’t the Ritz but compared to C-rats they are gourmet. Always have MREs for SHTF

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  13. Nebraska Dave November 17, 00:45

    Ha, try eating K-rations. World war II field kitchen rations. I was stationed in Germany for 1 1/2 years during Vietnam action. Our team of 30 was in charge of security and maintenance on a missile base. The food rations for the team that came in every week had dates on them that were older than I was. The old cook sargent for the team was a master at taking all that dehydrated stuff and making a half way decent meal. I didn’t even know that a steak could be dehydrated but those dried out fiber bricks actually could be hydrated up and made into Swiss steaks that weren’t too bad. Many would eat off base but I was just too cheap for that. I don’t remember any digestive issues but then a 20 year old male gut can with stand almost any thing.

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  14. Gman November 17, 13:57

    I was drafted in1962 an we ate our share of C-Rats. Some were from WWII and most from Korea . They had been over stamped I don’t know how many times. They said they were OK to eat. Some were not to bad but Ham & MF’s I couldn’t take. The burger patties the dogs wouldn’t eat.As for MRE’s I have some but never ate any of them yet.
    My friend who was in SF foe year still take “Probiotics” I guess it is an old habit after 30 years in the Army.
    When you get really hungry you don’t become very picky.I like the new freeze dyed meals OK.
    Stay Frosty. Gman

    Reply to this comment
  15. Karen November 17, 18:44

    LOVED all the comments from Veterans. Thanks for protecting America. And Mr. Davis, your writing is exemplary. Major Kudos!

    Reply to this comment
  16. Lucy November 19, 02:38

    Thanks for the very descriptive article, and all the comments from those who’ve experienced the C-rations, MREs, K-rations in the harsh circumstances they were designed for.

    In a SHTF scenario, if you were bugging in and trying to put by some things to help maintain the health of your intestinal flora, what would help besides making your own sauerkraut or kim chee, vitamin C, and magnesium? Unless you had access to some sort of fresh dairy, no yogurt or kefir would be available. What else would help?

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  17. Kafir November 22, 03:41

    I have about 20 cases of MREs for emergency…along with 8 months freeze dried. Also have dozens & dozens of jars of home grown and canned veggies and fruits (from the farmers market), canned meats, home made beer, etc. A good variety. I’ve been adding more home canned goods over the years so I have a good mix of foods along with the quick and easy MREs for the patrols and hunting during the apocalypse…can’t wait!!! 😉

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  18. Enigma December 2, 18:55

    A single MRE each day would extend your supplies of ‘real’ food. Per above military advice, don’t plan to live on MREs exclusively. Basically transit ‘food’.

    Cabbages keep pretty well in cool dry places, as do tart apples. With some vinegar (a prepper should always have vinegar), salt and pepper, you have German-style cole slaw and thus Vit-C and fiber.

    Better, get a book on edible botanicals for your area (or target area) and study it. Never eat wild mushrooms; nasty painful way to die.

    Reply to this comment
    • left coast chuck May 10, 17:13

      Yes, and by the time you discover that the mushrooms were not what you thought they were it’s way too late to do anything about it. Better start digging if you want to be buried in a hole.

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  19. Enigma May 17, 18:36

    About the only nastier way to die than mystery mushrooms is by consuming anti-freeze (ethylene glycol), Yet some manufactured ‘foods’ purposely contain the latter.

    Whenever seeing those lists of chemicals on reverse-side labels, I see Red. Read that tiny print, and y’all will be putting many things back on shelves. And saving money too…

    Reply to this comment
    • Homesteader May 17, 22:39

      Aren’t you thinking of propylene glycol? PG is the food additive. Ethylene glycol is poisonous. Either way, they’re both still used in antifreeze.

      Reply to this comment
    • young prepper April 10, 17:36

      i always look at labels while my father and i are shopping (it gives me something to do while listening to music)
      and i think “holy sh*t are these companies trying to poison us?” but my dad wont falter from buying food as opposed to eating what i find (Plants) or kill (animals) sometimes i wonder whether i’m more intelligent in terms of anti-currency survival than he is….

      Reply to this comment
  20. Enigma May 20, 13:39

    Neither kind of glycol we’ve cited is food. Such result from a synthesizing process. Both synthesizing and refining (isolating a single or a few molecules) are problematical. Those are the methods used to attain poisons such as synthetic opioids and cocaine.

    If a manufactured ‘food’ contains anything which is other than a common-place found in Nature (e.g., salt, honey…) and naturally-derived substances (e.g.., beef, tuna, kidney beans- very likely it’s not food. (Nature isn’t uniformly kind – there’s nigh always some quibble, such as babies and diabetics needing to avoid ingesting honey.)

    Food results from either the natural but complex processes inherent in plants and animals, or via some historic and relatively simple process, such as desiccation, fermentation, and/or distillation.

    People may of course consume whatever they see fit, yet the good and enduring life is attained and maintained by consuming only simple substances derived directly from Nature which are then simply prepared. Complexity is a path whereby lethal mistakes get made.

    Items such as wine and cheese result from natural processes – ie., fermentation. Humans have discovered and deploy many particular fermentation agents to generate varieties of alcoholic beverages and cheeses, and such are beneficial after centuries (millennia) of ‘testing’. But substances which are novel (invented in the last 100 years or so) are too likely poisonous. Generally such novel things exist mostly to enhance corporate profits, not health.

    There’s also a vast range of ‘foods’ discovered / invented in Asia, many resulting from natural processes. Such as fermented seafoods. Yet personally I’ll avoid consuming anything which smells like a long-dead animal or which is preborn young.

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  21. MikeyW July 19, 20:24

    Ate both C-rats and MREs during my 37 years In the Army. C-rats hurt like hell when you had to hit the dirt with them in your pockets. I still have a P38 or two. They still open cans when the electricity is out.

    The first MREs were labeled as made by a company called “Cadillac.” We were convinced that it was the Cadillac Dog Food company because of the texture and taste. The newer ones are much better. Tastes differ, and it wasn’t hard to trade what you didn’t like for something the other guy liked.

    As far as fiber goes, a comedian on a USO tour in Iraq made a joke about having eaten five MREs and “so far, none of them has found an exit strategy.”

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  22. Annoyed Marine October 18, 11:53

    Dumb, let me sum it up for those that have no clue. Let’s start with my experience (USMC), five 7 month deployments nothing but MREs. Oh but when you’re hike you say? Yeah a bout a Third of that is eating MREs. Those that get stopped up aren’t drinking enough water.

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