TIL You don't lose more heat from your head than anywhere else on your body. The myth came from a 50's army field manual with some suspect experimental procedures.
Yeah and I don't think OP's labelling this as a "myth" is really clarifying anything.
It's not "true" or "false": it's an overly vague and broad generalization from one study.
It's like if someone told you "You eat half of your fat at breakfast".
Is that true or false?
Well, it depends a lot on which "you" you're talking about and which day you're talking about, but in any case it doesn't make much sense to generalize it into some sort of bizarre universal truth or falsehood.
If you click the British Medical Journal link, it states that you'll lose about 50% through the head when clothed in -4C weather. This article would only be accurate if you qualify it by saying "nude in -4C weather, you'll only lose 7-10% of body heat through the head"
The article also mentions another experiment done about 20 years ago with swimmers and the same body heat measurements, with results showing that heat loss was correlated with area exposed. It's a poppish article but the background behind the myth was the big TIL for me
I think in that study they had a bunch of dudes all dressed up in winter gear but no hats. Then they got all shocked when they saw heat dumping out of their heads. Then they put hats on all of them, and shocker, less heat loss.
I always heard this in scouting. Might be incorrect but it still does a great job getting the point across. You’ll be a lot warmer with a beanie vs no beanie.