I have a few cases of these stashed away. I think they're tastier than store bought dehydrated (Mountain House and such), and both options aren't exactly healthy.

I grabbed three from the top of the box, just to give an idea of the calorie to weight ratio.

-Macaroni in beef sauce: 1270 cal, 1.01 lbs. (79 calories per ounce)
-Homestyle chicken w/ noodles and veggies: 1190 cal, 14.95 oz (80 calories per ounce)
-Pasta with garden veg in tomato sauce: 1230 cal, 14.75 oz (83 calories per ounce)

So they're all hovering around 80. Mountain House meals are usually around 120. However, I haven't taken apart an MRE and removed the toiletries, heater, heater pouch, and tube of salt water to activate the heater. I received these cases after a hurricane a few years ago, and they are different than the ones distributed after Katrina. The outermost packaging is different, and the military version didn't contain the tube of salt water.

Other than weight, the MRE is a mush more complete meal. Compared to the MH Lasagna in meat sauce (the only one I happen to have):
Total fat: ~83% in the MRE, vs 30% in the Mountain House.
Sodium: ~50% vs ~30%.
Carbs: 180g (about 50%) vs 68g (about 23%)
Protein: ~30g vs 35

All of these vary from meal to meal, especially cholesterol. Unlike the Mountain House, the MRE is more than just a main course. The ones I have also include an oatmeal cookie, a pop tart, drink mix, peanut butter, and a cracker. The version I had after Katrina varied in the side dishes, so maybe these are a civilian version for emergencies.

I'd never considered them an option before this thread. I'll have to take one to work and weigh it without all of the extras.