Gum Doesn't take Seven Years to Digest...

and most of your heat isn't lost by your head.  Eight “Facts” about the Human Body Debunked by Science:

As legend has it, they dressed volunteers in arctic survival suits and observed how their bodies reacted to freezing-cold temperatures. The military concluded that the volunteers lost most of their heat from their heads, seeming to ignore the fact that the head was the only body part that wasn’t protected from the elements.
Two decades later, a US Army survival manual incorporated those findings, stressing the importance of covering the head when exposed to cold conditions to avoid losing “40 to 45 percent of body heat.” A myth was born.