Do You Really Lose All Your Body Heat Through Your Head?

With chilly days right around the corner, parents everywhere will soon start sternly reminding their kids to wear hats when they go outside, because "most of your body heat is lost through your head." But is this common belief actually true?

The notion that heat escapes from our heads faster than from any other body part seems to have its origin in a decades-old U.S. Army field manual, which claimed that between 40 and 45% of body heat could be lost through the head (via Live Science). This myth was investigated in 2006, when scientists examined heat loss while submerging individuals in cold water. Some wore wetsuits and others did not, and some submerged their heads while others did not. The researchers found that, contrary to popular belief, heat loss was fairly proportional to the amount of skin that was exposed to the cold. The head accounts for around seven to 10% of the body's surface area, and approximately that amount of heat loss as well.

Wearing a hat on cold days is still a good idea

Dr. Michael Stern, an emergency medicine physician at New York Presbyterian, confirms, "The head as a body part represents about 10% of the average adult's total body surface area, so in reality only 10% of your body's heat is lost from your head" (via Yahoo! News). Heat loss has more to do with general exposure to cold than with any body part specifically, so technically you can lose just as much heat through your feet as your head. The difference is that in chilly temperatures, your feet are normally insulated by socks, slippers, or shoes.

Richard Ingebretsen, an adjunct instructor in the department of internal medicine at the University of Utah School of Medicine, told WebMD, "The real reason we lose heat through our head is because most of the time when we're outside in the cold, we're clothed. If you don't have a hat on, you lose heat through your head, just as you would lose heat through your legs if you were wearing shorts." So if you want to hold in that precious heat on a chilly day, it may be a good idea to cover up with a hat.