Hello folks, I keep reading this one and it gets repeated by every instructor I've ever heard. It's not true, the Canadian army did testing with the troops wearing cold weather gear but no headwear. So big heavy boots, mitts, arctic parkas-you get the picture. Then they measured the heat loss with the instruments available at the time and concluded that the majority of body heat is lost through the head. Subsequent and more recent testing on near naked folks proves that the head looses heat at a rate not much more than the rest of the body. The head has little fat and high blood flow so it does lose heat faster but not to the tune of 75% of your total body heat.
On the other hand when the Innuit act as guides they insist that the clients cover their heads in cold weather, and it makes good sense to me. A woolen toque is perhaps the worst way to cover your head by the way as it doesn't prevent heat escaping through your collar and does nothing for your neck. A fur hat is a good way but still not as good as a good hood on your parka, the fur hat and the hood is the bomb though! In extreme cold I'm amazed that a hood will create an area of warmth around your head that's quite nice indeed and works well to keep your face warm too, especially if it's one of those wire rimmed hoods that can be drawn in quite tight with a small opening.
That feels better, I had to get that one off my chest!