That old wives tale is absolute B.S. I can't locate the link that explains how that erroneous conclusion came from a legitimate study that contained an erroneous calculation.
Just ask any competent Mechanical Engineer for an opinion on that nonsense.
Same with global warming where less than 1/2 of 1 percent of the atmosphere is supposed to have such a huge affect.
Only if you don't have a coat or a snowsuit on...
If everything else is insulated, the heat flow from the head will be more significant.
(But, iirc, the real number is closer to 40%).
I will check on the exact statistics on that.
However, if you have a cold, the idea is to stay warm and putting a cap or scarf on your head is another way to keep warm..just like wearing a sweater or warm socks.
Just ask anyone with the flu or a cold, how good it feels also to have something on your head...that can’t be all imaginary. The body knows you are keeping it warm.
But I will check this out.