When I was growing up, my Mom taught at a Catholic grade school where the priest gave basically the same sermon to the children every day in winter. Instead of probing any deep theological message, he offered this PSA at morning mass: "Your head is like a chimney. Wear Your Hat." My mom would remind my sister and I to wear our own hats when it was cold out, by jokingly repeat the same manta.
This leads me to the last mythbuster for now: you lose most body heat from your head. This statement is partially true, depending on the context.
I've heard several different competing claims the amount of heat loss from the head, but the various estimates range from 75% to 95%.
If this were true, then one should be able to to stay extremely warm by simply wearing a ski mask or hat while nude. Yesterday, it was 10 below (F) in Wisconsin; however, I decided against conducting the full experiment.
The brain is an extremely metabolic active part of the body and it does produce more heat than other parts of the body (like the pink finger); however, the heat is lost more from the head as in modern Western society, it is normally uncovered while the torso, arms, and legs are fully clothed.
If the entire body is covered, including the head, there is a very little heat loss anywhere. Likewise, if the entire body is naked, then heat is lost from all surfaces and the percentage from the head does not come anywhere near 75%.
What is more likely true is this: of the body heat that is lost, the head contributes the majority when it is directly exposed to the environment while the rest of the body, except for the hands and feet, are fully clothed.