If you had to add water, they weren’t MREs. What you are recalling is probably LRRP rations. Those were packaged in brown and were dehydrated. I never liked them. Too salty and no texture at all.
Johnny, the civvy MREs don’t come packaged with heaters, but you can buy them seperately.
I’m a fan of that pound cake too, the lemon pound cake being the best.
Silenus, I’ve seen civvy versions of MREs in the Commissary, and IIRC, they had heaters in 'em. I’ll go buy one this week to verify, but I was pretty sure they did.
Tripler
Conisseur of the HMMVW engine block heating method.
They didn’t used to come with heaters, because you can’t ship those Parcel Post. If Sopakco has switched to UPS, then there isn’t any problem. The last case I bought had them, a dozen heaters tossed on top of the MREs. Hmmmm…about time to eat these up and cycle through the earthquake supplies. Maybe I’ll get some more Canadian IMPs this time. Those were tasty!
You may well be right. My experience was well before Gulf One and as I left the supposed MRE was a big, new deal.
I eat MREs at least once a month. (I belong to a militia group.) If fact, I just had one yesterday.
An MRE is a plastic bag containing food. When you rip open the bag you’ll find 3 or 4 food items. Each food item is individually encapsulated in a plastic bag. You’ll also find a heater, condiments (e.g. hot sauce), drink mix, paper towel, gum, and a plastic spoon.
As far as the food items go, there’s usually 1 entrée and 2 or 3 snacks. To eat the snacks, simply rip open their plastic bags and eat them. The entrée can also be eaten in the same manner, but most people like to heat it before eating.
To heat the entrée:
To be honest, most of the MREs I have eaten have actually been pretty good.
FYI, I believe the heater is just a plastic bag containing iron powder. When you add water to the heater, the iron quickly rusts, and the chemical reaction is exothermic.
A few additional tidbits about MRE’s:
MREs are designed to constipate you. Why? Because when you’re out fighting, Uncle Sam wants you fighting, not sh*ting. That’s why MREs are sometimes called Meals Refusing to Exit. 
If you eat an MRE, but do not want to become constipated, you should chew the gum. The gum is a laxative.
Due to its constipation properties, it is generally advised not to rely solely on MREs for more than 1 week.
Good post Crafter_Man, but I doubt if the gum is a laxative. That’s a common rumour, I’ll admit.
A MRE consists of an Entree, and all/most of the following- a side dish, a cracker/bread, a desert item, a cold beverage or hot chocolate and an accessory pack with a beverage (tea or coffee), a tiny botttle of Tabasco, salt, gum, matches, sugar, creamer, and toilet paper. The accessory pack can sometimes be bought separately (try eBay), and makes a good small makeshift “survival kit”.
The meals aren’t designed to be consipating, but by their very nature they aren’t high in fiber, nor very hydrating.
OP, I suggest you buy a couple of them and try them out. Or, better yet, get a dozen and try one out, then use the rest ar your Emergency rations.
My ex-military buddies keep a couple in their desks at work for when they have to work through dinner. I’ll take a look at that site up above and see if I can pacify my wife’s survivalist urges by buying some of those…
Don’t forget the pouch. The exterior pouch of an MRE is resealable, waterproof and durable. It provides a good place to store bottles of medication, precious photographs you took as you left a flooded house, etc. It can also be used as waterskin, stomach distress bag, or emergency urinal.
Kosher and Hallal MREs are available.
Check ebay. They always have cases upon cases of MREs for sale. Just be sure to get ones that are date-stamped 2007 or later. That insures that they are current-run, and not ancient. Cases are either A or B.
Menu A contains these Choices.
01 - Beef Steak w/ Mushroom Gravy
02 - Pork Rib
03 - Beef Ravioli
04 - Country Captain Chicken
05 - Grilled Chicken Breast
06 - Chicken/ Thai Sauce
07 - Chicken w/ Salsa
08 - Beef Patty
09 - Beef Stew
10 - Chili w/ Macaroni
11 - Pasta w/Vegetables
12 - Veggie Burger w/BBQ sauce
MENU B
13 - Cheese Tortellini
14 - Pasta w/Alfredo Sauce
15 - Beef Enchiladas
16 - Chicken w/Noodles
17 - Beef Teriyaki
18 - Turkey Breast w/Gravy
19 - Beef w/Mushrooms
20 - Spaghetti w/Meat Sauce
21 - Chicken Tetrazzini
22 - Jambalaya
23 - Chicken w/Cavatelli
24 - Meatloaf w/Gravy
I generally prefer the chicken entrees. YMMV.
Dude, what’s in those? I’ve never heard of 'em. 
I’ll send you my address, you send me one, I’ll send you a Mil MRE and the “civvy” one I was talking about.
Deal?
Tripler
Just let me know, eh!
Quoting Crafter_Man, I have a slightly different method:
To heat the entrée:
Remove the entrée from its cardboard box.
I haven’t run any convoys through Baghdad yet, but did it on several exercises. I’ve had 25-year CMSgts (E-9s) amazed that you can do this. It’s like . . . duh!
It’s some iron/zinc compound that heats up when the water interacts between the two. I think you’re right though, the zinc accelerates the oxidation of the iron, generating heat. If I had one handy, I’d tell ya.
I’ve never heard they were designed to constipate you. Granted they do, but for some reason, it doesn’t strike me as practical to do so by design. Fecal impaction can be a damned problem.
The gum is just “Chiclets”. I can’t see the Adams Gum company adding a laxative to their gum just for the helluvit. I could be wrong tho. . .
I actually did live on MREs for two weeks. My first deployment to Kuwait in Sep '01, we lost power to our chow hall (for dubious reasons) and were issued MREs for two of three meals (thank GOD for Services!!). I pooped fine, but I will admit, the menu got boring after one week.
Maybe my bowels are built for the fortitude of such endeavours.
Tripler
The world may never (and never want to) know.
I used to heat my MREs (which I’d take to work for lunch) by putting them on the dashboard of my car. When I’d open one at lunch time, the contents would be steaming.
I thought they were called SOS.
Nah. SOS is Creamed Chipped Beef on Toast. That gets served in the mess, or in field kitchens. If they ever put it in MREs there would be wholesale mutiny! 
I must admit that I do not know for certain if MRE’s are designed to constipate you, and/or if the gum is a laxative. So I apologize for stating these as facts. But the rumor has been very widespread in various military & militia message boards for a number of years. I even have a book where the author states these rumors as facts.
So what’s the straight dope on this?
I did some google searches, but I couldn’t find an authoritative cite to substantiate the rumor.
Deal. I just sent you an email about this.
Canadian Individual Meal Packs are paper wrapped rectangular boxes, with the pouches inside. Some different menus, which makes for some variety in the diet. See here for more info. You can occasionally find them on ebay, which is where I got mine.
Whatever you do though, don’t drink the water that you used to heat up your meal with. That’s bad. That’s really bad.
In Basic, one girl drank the water. They had to call the ambulance and all that jazz. Afterwards, they had a talk with us:
“We give these to Iraqi refugees sometimes. They don’t speak English, and they know not to drink the water. There’re pictures showing you not to drink it.”
Not to mention warnings all over the packaging. Oh, well. Think of it as evolution in action.
In Basic, they showed us how to make a makeshift bomb out of the heater.
Then again, I had batshit insane drill sergeants. 
To elaborate, SOS = Shit-on-a-shingle. My dad, who was in the navy in WWII, used to talk about this with a sense of horror he otherwise reserved for kamikaze attacks.