Seeing so many people get in trouble because they don't know what they're doing in the cold nearly drives him mad. Every item of clothing he puts on his body, and on our soldiers, he has tested in action. He knows what works. You need to eat more fatty, slow-burning foods. Drink at least one or two quarts of water each day.
Dehydration can be as severe in winter as in summer.
If you go winter camping, know that by insulating your feet and hands at night, you'll double the effectiveness of the bag. Fluff up the bag before getting in. And since the moisture you carry into the bag will condense and make a wet, chilly bag, sit up in the bag before burrowing in. Be sure you're dry. You'll lose a pint of water into your sleeping bag at night, so when you awaken, you need to dry it.