Sometimes, when I’m really cold, it can take over an hour to warm me up, even with a heating blanket. The quickest solution, a hot shower, feels really inefficient with all the heat going down the drain.

That got me thinking about microwaves. They heat food (partly) from the inside, contrary to simple infrared radiation.

Could we safely do that with people?

I found a Reddit thread where a non-lethal weapon and people getting eye damage because they stayed too long in front of a radar dish.

Could some sort of device be made that would warm specific areas (say, a hand or a leg) without endangering sensitive areas like the eyes?

Would it actually warm someone up from the inside? Would it be possible to make it safe?

Would it present advantages in cases of hypothermia, compared to heated IV fluids?