Almost all pre-cooked meals/entrees I’ve come across require 3-5 minutes in a typical microwave (according to instructions, which usually works out alright). However, I’ve recently seen a couple that call for just 1 minute in the microwave (actually needs 10-15 seconds more than that if you want it properly hot).
Both of them are rather soupy concoctions (Dinty Moore stew, and Kraft cheesy bowls), but even actual soup doesn’t warm up that fast.
What do the food engineers do to make these dishes able to warm up so quickly?
I’m just guessing here - but the basic mechanism of microwaves is to hit the food with waves that are a frequency that will excite the molecules of water. Most food has water in it, so heating the water effectively cooks the food. It makes sense to me that food that is predominantly water would heat faster.
If the food is already cooked, room temperature and has lots of water in it (like a soup or stew) then all you need to do is warm it up and that happens pretty fast.
Also, the volume of food being cooked matters so a small, single serving, will heat pretty fast.
Design of the container heals as well. If its made of a foil-like substance embedded in paper or plastic, it will get very hot, very rapidly. Just so long as there’s no “antenna-like” foil sticking up to cause the magnetron to arc, there can be aluminum foil in the container.
This is what I think the likely answer is. Check the weight of the meals; many of them are made in certain portion sizes which are actually fairly small. I microwave family sized portions of frozen and left over food every day, and soup for 6 does take 5 minutes or more.
The volume of some individual portioned meals might fit into a coffee cup though. Especially if the food is calorie-dense; the amount needed to make up the X-calories those portion sizes are based on can be pretty small, and wouldn’t take long to heat up.
Dinty Moore and Kraft Cheesy Bowls start out at room temperature. If you’re comparing them to things like Lean Cuisines or Hot Pockets, those have to go from about 0 degrees F all the way to about 65 degrees (evenly, in a perfect world), before you can compare the two. So the Dinty Moore/Kraft Cheesy Bowls have a multi-minute head start.
For a proper comparison, everything needs to start out at the same temperature. I suspect you’re comparing room temperature food to frozen food.
A thawed out frozen dinner would probably be scalding hot after a minute or so in the microwave as well.