You Lose Most of Your Body Heat Through Your Head
"The belief that a large share, often cited as 40-45%, of your body's heat escapes through an uncovered head."
Traced to a 1970 US Army survival manual, which reported that 40-45% of body heat is lost through the head. The figure came from a flawed experiment: soldiers were dressed in full arctic survival suits covering everything except their heads, so almost all the measurable heat loss naturally showed up there, since it was the only skin left exposed. A 2008 British Medical Journal review corrected the record: the head makes up roughly 7-10% of the body's surface area, and loses heat in rough proportion to that, no more special than any other uncovered patch of skin.
Myth vs. FactThe original number came from a badly designed experiment, not new science. Heat escapes wherever skin is exposed, not disproportionately from the head.
Sources: US Army survival manual (1970); corrected in British Medical Journal (2008).