How much body heat do you actually lose from your head?

Have you heard somebody (probably your mom) tell you to put a hat on because you lose a significant percentage of body heat out your head alone? I’ve heard that number quoted from 50-90%. When I asked, “Why do you lose so much heat out your head?” I got an answer along the lines of “Your brain needs lots of oxygen and the blood takes it there and so there is lots of blood in your head, which lets all of your heat out.” That reasoning is not true and wearing a hat isn’t as crucial as Mom implies it to be. Although you don’t lose the majority of body heat out your head, it is still prudent to wear a hat when it is cold, just like you wear pants and long sleeves when it is cold. Wear a hat, it feels nice.