How to Prepare an MRE with a Flameless Heater


How to Eat an MRE with a Flameless Heater

If you don’t know how to properly eat an MRE, or prepare one that has a flameless heater, you should. MREs are an excellent tool to keep in your prepper toolbox, should you ever face an extended-length survival or emergency situation. Grocery stores can be highly unreliable during natural disasters and emergencies, so it’s wise to stockpile long-lasting food like these, just-in-case. 

What is an MRE?

MREs are the primary food ration of the United States Armed Forces during combat operations. MRE is an acronym for “Meal, Ready To Eat.” You may remember c-rations or k-rations from World War 2. MREs are the modern-day version.

These meals are designed to provide a soldier with all of their caloric and dietary requirements while in a combat situation. They can be eaten warm or cold and are incredibly shelf stable. MREs come in heavy bags that are meant to withstand significant abuse.

The Contents of a Typical MRE

MREs are offered in a few dozen different menu combinations, but all military style MRE bags contain the following:

  • The main entree
  • Side dish
  • Crackers or bread with some type of spread
  • Dessert
  • Candy
  • A powdered drink mix
  • Non-food items (utensils, toilet paper, etc.)
  • Sometimes they’ll have hot sauce or other seasonings, and a flameless heater for heating up the entree.

Instructions for Eating an MRE with a Flameless Heater 

Preparing an MRE to eat using a flameless ration heater is incredibly easy.

  • Step 1: Open the bag and locate the small packet labeled ‘heater.’ Read and follow all safety precautions printed on the packet.
  • Step 2: Fill the heater packet with water to the designated ‘fill line.’
  • Step 3: Remove the entree packet from its cardboard container and place it in the into the water.
  • Step 4: Fold the MRE heater bag closed with the entree packet inside and let it sit at a slight incline so water is directed towards the bottom.
  • Step 5: Wait approximately 2 minutes while your food is warmed up.
  • Step 6: Remove the entree from the heater (careful, it will be hot!), open the top, and eat directly from its bag using the provided utensils.

Other than the drink mix (just add water), all the other components are already prepared and ready to be eaten. That’s it! Enjoy your piping hot meal that you heating up in only a couple minutes thanks to your flameless ration heater!

Before you purchase pallets of MREs for your bug out location, I strongly suggest you taste a few first to see if they’re something you and your family can eat. There are plenty of other long-term food options out there! Personally, Chicken Parmesan is my favorite MRE option.

Common Questions (Q&A)

Where can I purchase MREs?

On every case of MREs (they come in boxes of 12 meals each), the following words are printed in great big block letters: “U.S. GOVERNMENT PROPERTY. COMMERCIAL RESALE IS UNLAWFUL.” The makers of MREs are not allowed to sell them to the general public, but this doesn’t mean that it is difficult to find MREs for purchase.

You can purchase authentic second hand military MREs online, often from eBay suppliers.

Or, you can buy what is known as “Civilian MREs.” There are currently five manufacturers of Civilian MREs, making them quite easy to purchase. Frequently, the civilian MREs are in better condition than their military counterparts. Since about 2005, after Y2K and Hurricane Katrina increased demand for MREs, the civilian MREs became just as good as the military ones. Also, the civilian MRE vendors are often more reliable. Your meals are more likely to be received well before their expiration dates and more likely to have been stored correctly prior to your purchase.


How do I know if my MRE is still safe to eat?

The answer to this will depend upon two factors: how long it has been stored away, and under what conditions.

Officially, MREs should be stored at temperatures no higher than 80 degrees Fahrenheit. At this temperature, they have a shelf life of 3 years. Warmer temperatures will naturally shorten their shelf life and nutritional value. For instance, if they were stored at 120 degrees, the shelf life would be only about one month. Conversely, storing at colder temperatures increases shelf life; at 50 degrees, the shelf life is as much as five years. Click here to read more about MRE shelf life. 

Expected MRE Shelf Life at Various Temperatures

  • 120°F = 1 Month
  • 110°F = 2 Months
  • 100°F = 6 Months
  • 90°F = 18 Months
  • 80°F = 36 Months
  • 70°F = 40 Months
  • 60°F = 48 Months
  • 50°F =  60 Months

As long as MREs are still in the case, there is an indicator on the outside of the box that can also help determine if the they’re still good to eat. This is known as the TTI, or ‘Time and Temperature’ Indicator. It is a dark circle with a lighter circle on the inside of it. As long as the inside circle is still lighter than the outside ring, the MREs inside should be okay to eat.

eat-an-mre-time-temperature-indicator
Handy right? If only all food could be this easy to inspect and judge.

This, of course, is based on official recommendations.

On a practical level, so long as the individual components aren’t damaged – torn, punctured, etc. – or they aren’t swelling (swelling is very bad), the food inside should still be fine. If it is past it’s official expiration date, it may be missing some nutritional value and flavor.  It probably isn’t in your best interest to source your daily nutrition from old MREs but he occasional meal should be fine.

Can You Eat an MRE Without Cooking It?

Yes, it is possible to eat an MRE without cooking it. After all, it says so right in the name: ready to eat!

Since MREs are intended for military personnel out in the field, it is easy to imagine a somewhat precarious situation in which they can’t find water. If you choose to eat your MRE without cooking it, you’ll probably find it to be not as tasty, but still edible and retaining all of its nutritional value.

If you wanted, you could even eat the drink mix without the water. Again, not ideal taste-wise but under certain conditions, it could be necessary.

Can you cook an MRE without using the flameless heater?

Yes, you can cook your MRE without using the flameless heater. The flameless heater’s purpose is only for heating up the entree. You could just as easily build a fire and drop the entree packet in a pot of hot water if you’re not a fan of the flameless heater.

There’s really no down side to this other than the fact that this method is usually a little more labor intensive than just using a flameless heater.

Are MRE packages microwaveable?

No, MRE entree packages at not microwaveable. Their specialized packages contain a foil like substance inside making them not safe to heat in a microwave. It will destroy the packaging, ruin the food inside, and possibly damage your microwave.

Have you ever accidentally put silverware or aluminum foil in the microwave? If you have, then you know what will happen if you put an MRE package containing a foil like material inside your microwave. There will be lots of sparks and it might even catch fire. Not good.

Are the flameless ration heaters reusable?

Flameless MRE heaters are single use only. They should be discarded after use.

However, you can very easily use one heater to warm up two MREs at one time. Just insert both MRE entrees into the heater at once instead of one. The heater pouches are made large enough for this purpose and the heaters themselves are plenty powerful to sufficiently heat two packages at once.

How do the flameless heaters work?

They are essentially a plastic bag filled with a specialized substance inside that chemically reacts when exposed to water. This substance consists of a very specific ratio of magnesium powder, salt, and iron powder.  Once water is added, a chemical reaction begins to take place. This chemical reaction produces hydrogen gas, and in the process, heat.

Can a flameless ration heater explode?

Generally, flameless ration heaters are considered safe if used as directed and the only hazard to be concerned about it getting burned by the heat it produces. However, it is possible to make an explosion utilizing a flameless heater from an MRE.

The chemical reaction that takes place inside a flameless ration heater when it is exposed to water produces hydrogen gas. So if the powder from an MRE heater is in a sealed container after being exposed to water (such as a soda bottle), it will produce enough pressure to cause the container to over-pressurize and burst.

Also, since hydrogen gas is flammable, keep your MRE heater away from open flames while cooking or you could have a fireball in your hands.

eat-an-mre-military-eating
MREs were originally created to provide for highly active military men. If you’re not exerting yourself during the day, you probably won’t need to eat 3 MREs (nearly 4,000 calories) a day.

How many MRE’s should I eat each day?

Each MRE contains about 1,250 calories. The recommended caloric intake varies greatly for each person, but the estimated average is roughly 2000 calories, per person per day. MREs are intended to be eaten three times daily, and each MRE contains roughly one-third of the daily recommended vitamins and minerals. 

Eating three MREs each day would result in you consuming 3,750 calories daily. This may seem like an excessive amount of calories, but keep in mind that MREs are designed for highly active military personnel. If your day isn’t as intense, you can probably get by with 1-2 MREs a day without an issue.

To find out how many calories you should be eating per day, check out this calorie calculator.

As stated above, if your MREs tend to be on the older side, they may have lost some nutritional value. Therefore, you probably shouldn’t eat older MREs for every single meal. But combining them with other nutrient-dense sources should be perfectly fine.

Can I live off MREs indefinitely?

Despite all of the work that has been put into making MREs nutritionally valuable, the fact is they were never meant to be used on a prolonged basis. According to the Army, MREs are intended to be used for up to 21 days, while still being supplemented with fresh rations. They are a high-energy food source, but are not meant to sustain a balanced diet over an extended period.

MREs are lacking fiber. This means that if you do plan to try living off MREs for an extended period, you should supplement your meals with high fiber foods such as fruits, dark colored vegetables, or potatoes. They are also high in salt, so you will likely need to drink extra water as well.

What happends if I eat too many MREs in a row?

To achieve their impressive shelf life, MREs contain a lot of preservatives. In that sense, they are like junk food. Of course, junk food isn’t made to sit on a shelf for years at a time.

The result of eating too many MREs, is pretty similar to what the result would be from overeating junk food: constipation, or diarrhea. This is exacerbated by the fact that the MRE is also very low in fiber. In fact, the packet of bread or crackers is pretty much the only fiber you’ll find in an MRE. In short, do yourself a favor and don’t eat too many.

Here’s what’ll happen to your body if you eat too many MREs (be warned – it’s not pretty).


Now it’s time to hear from you. Do you plan to store MREs for a disaster situation? Comment below and let’s help each other out!

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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