Interestingly enough, when I was in boy scouts my troop leader advised us to wear panty hose underneath our thermal underwear when we went on snow camp outs and such. He said it's another layer that traps heat close to the skin.

This coming from a huge 300 lb high school autoshop teacher with a built up diesel van that wouldn't slow down for any hill. We asked him what color he wore and he said pink. I don't think any of us took him up on his advice that time.