What Happens to Your Body If You Eat Too Many MREs

What eating too many MREs will do to your body.

MREs, or Meals Ready to Eat, are a self-contained food ration, often used in military training or combat. They are made available when there are no other food options, or when the commanders want to punish the unit. Sometimes they are sold as disaster-preparedness items to be used during the zombie apocalypse or just for regular old camping during the zombie apocalypse.

They are also popular for distribution among refugees and displaced civilians during natural disasters. But it turns out the biggest natural disaster will happen in your pants if you eat too many MREs for too long.

The Military Studies

The military and the entire United States Department of Defense recommends the light use of MREs, no more than a few days in a row. If you are insisting on testing this out, they highly recommend never eating MREs for more than 21 days in a row.

To verify these figures, the Defense Department regularly conducts studies on the heartiness of the human body against the unstoppable juggernaut of a 21-day MRE diet. These poor souls are then researched to aid in the improvement of MREs for soldiers stuck in the field.

What Can Happen In Your Stomach?

The consequences of eating a lot of MREs are very serious. The stomach is responsible for most of the auto-immune functions of the body, and upsetting it can throw your body into unmitigated terror and illness if not taken seriously.

Most chronic stomach complaints are a sign of an underlying auto-immune issue that may or may not have evolved into a full-fledged disease. These include Irritable Bowel Syndrome, Celiac’s Disease, Type 2 Diabetes, and Cancer, to name just a few. So proceed down the MRE road with caution.

A man who ate too many MREs.
Eating MREs for more than the recommended maximum of 21 days can cause some serious intestinal issues.

The Constipation Experience

One of the most common side effects of an MRE-only diet is severe constipation, sometimes alternating with severe diarrhea. There was a recent article published about a civilian who ate nothing but MREs for 21 days straight.

This poor fool ate two MREs a day for 21 days and lived to tell the tale. He reports bouncing back and forth between a bloated, sweaty constipation and gut-wrenching diarrhea. This is because a normal person’s digestive system is not used to the nutritional makeup of an MRE.

It has enough calories to sustain a human being for a whole day. Mind you, it is not enough to just eat one MRE per day, but you could survive for a very long time on its hearty 1,300 calorie count. Most people report bloating, gas, severe fatigue and intense constipation after eating just a few.

Why Does Constipation Happen from Eating MREs?

There are a couple different reasons for this. The MRE has a high calorie count, as well as a high fat content, a high protein count, and a staggeringly high amount of sugar.

The reason for these high amounts of slow-digesting and unhealthy ingredients is to give a person enough energy to trudge through the jungle all day and set up a military-grade camp at night that can pass inspection. They are meant to be eaten in one sitting and to be digested and used for extremely high levels of physical activity.

This poses a problem for your average Joe citizen. According to the Department of Health, only 51% of the U.S. Population meets the standard for aerobic exercise, and only 21% meet the standard for strength training exercise. Most people just aren’t active enough to handle the density and nutritional content of MREs. As a result, all these heavy ingredients end up clogging the pipes, within the body and within the McDonald’s bathroom.

Even soldiers who march all day and still have PT at night aren’t always able to avoid the constipation, especially after long-term MRE consumption. Another reason for this unholy constipation is the low fiber content in the MREs, which can be as low as 2 grams.

No fiber generally means no pooping. Just ask grandpa. At the very least, the average lazy person would get fat on MREs because they just don’t move enough.

Other Consequences of Long-Term Constipation

Once again, it is highly recommended to stay away from MREs as a long-term eating emergency food solution. The balance of stomach and auto-immune health are at stake. Even if that’s not enough to scare you off, there is some evidence to suggest that severe constipation can lead to death in certain cases. The basic gist is that straining while taking a poop can actually set off a heart attack because of the stress placed on your body.

Another terrifying possibility is a perforated bowel, which can lead to your undigested MRE leaking into your body’s cavities and causing septic shock. While this mostly happens to the sick and elderly, it’s not something I would toy around with.

Another potential danger is the shelf life of an MRE is relatively short, much shorter than many other emergency foods. It lasts only up to 9 months in hot conditions. So if you choose to store MREs for disaster-preparedness, be sure to do so in a cool, dry place. If your MRE has expired, throw it out.

Contents of an MRE.
The contents of an MRE is individually packaged, making it easy to split it apart so you don’t have to eat the entire thing in one sitting.

How to Eat MREs for More Than 21 Days Straight

So what can you do if you’re stuck in a situation full of nothing but MREs to eat? There may come a day where you hike the Appalachian Trail or are stuck in a bomb shelter and there is nothing but MREs. Well, fear not, because there are some steps you can take to ward off the evils of constipation and terror.

Split It Up

While MREs are meant to be eaten in their entirety in one sitting for energy, they can be easily split up since each item in the meal is packaged separately. This is actually fairly popular in dire situations.

Most people take the best bits and bargain the rest away for something better, and everyone wins. It’s not as simple as trading off though, because trading one bit of MRE for another will still result in that high calorie count.

Water It Down

The best way to tackle this problem is to water down MREs with vegetables or fresh ingredients taken from gardens and forests. While foraging like Red-Riding Hood isn’t always practical after a nuclear apocalypse, right now it is a perfectly viable option in many regions. Balancing that high protein meat with low calorie vegetables and mushrooms will help you avoid the pitfalls of constantly eating MREs.

Use Vitamins and Fiber Supplements

A good daily multi-vitamin will help your body by filling in the nutritional gaps that may occur with a diet that is not well diversified. Most multi-vitamins have a shelf life of a few years so it is not that difficult to keep a spare bottle or two on hand.

Also, if you are able to supplement your diet with additional fiber, it will do wonders for your digestive tract since fiber is lacking so heavily in MREs. Fiber and multi-vitamins are cheap and very light weight if you are trying to remain mobile.

These are all invaluable in the fight against constipation and other issues of the MRE. There are also many other long term emergency food options on the market that don’t have the same digestive problems as MREs. It is best to have a variety of these options, not just for flavor, but for cutting them with calorie-dense MREs in order to save your guts. Be sure to stock up on these other items if you choose to go the MRE route.

An emergency supply of MRE meals.
Stashing away a large supply of MREs as a long term food supply in a disaster is not a good idea.


In conclusion, there are a couple of solutions for a long term MRE eating plan, but they are not entirely practical and frankly, not worth the extra stress for my money. Because there are plenty of quality alternatives on the market, there’s no reason a disaster-preparedness stock should contain many MREs.

As for the military, the effects of MREs are well-documented, and most soldiers don’t get stuck eating MREs for too long. But just in case, plenty of water and some supplements will go a long way in saving your ass, literally and figuratively.

John Walter

John Walter is an emergency preparedness consultant with eight years of experience and training in related fields. He is a passionate prepper living in the Sacramento area of California.

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