Hats. The cold. The truth.

In the last few days I’ve heard a few rants over whether wearing a hat will keep your head warm. Honest. I hardly believe it either.

You see, the BBC posted a list of winter myths, and one of them was apparently ‘you don’t need to wear a hat to keep warm’. This has been lauded as a clear example of how scientists are a) stupid and b) change their minds every five minutes.

Well, guess what? Ranty people are wrong. The list of myths came from the British Medical Journal, and here’s how they describe it:

As temperatures drop, hats and caps flourish. Even the US Army Field manual for survival recommends covering your head in cold weather because “40 to 45 percent of body heat” is lost through the head.19 If this were true, humans would be just as cold if they went without trousers as if they went without a hat.But patently this is just not the case.

This myth probably originated with an old military study in which scientists put subjects in arctic survival suits (but no hats) and measured their heat loss in extremely cold temperatures.20 Because it was the only part of the subjects’ bodies that was exposed to the cold, they lost the most heat through theirheads. Experts say, however, that had this experiment been performed with subjects wearing only swimsuits, they would not have lost more than 10% of their body heat through their heads.20 A more recent study confirms that there is nothing special about the head and heat loss.21 Any uncovered part of the body loses heat and will reduce the core body temperature proportionally. So,if it is cold outside, you should protect your body. But whether you want to keep your head covered or not is up to you.

They’re busting the myth that 40-45% of body heat is lost through the head. That’s it. That’s all. To be concise:

  • Your head loses heat at the same rate as the rest of you.
  • If your head is the only thing exposed, you’ll lose most heat from it.

Nothing about whether you should or shouldn’t wear a hat. Is this clear from the above? Well, yes. Not if you decide you know what it says before you read it, though.