It's been pretty cold this week. Staying comfortable in the cold, whether you're walking around town or staying indoors, requires paying attention to the science of heat transfer. Keeping warm requires two basic principles:conduction and convection. Conduction is the transfer of heat between two solid surfaces that are in direct contact with each other, such as when standing on an icy pavement. Convection is the transfer of heat between a mass (such as your body) and a moving liquid or gas (such as an icy wind rushing around you). Understanding both of these mechanisms, as well as the workings of your body's built-in thermoregulatory system, will keep you warm and safe through the cold days ahead.
1. Wear layers
You lose heat through conduction when your body comes into direct contact with something cold, for example when you sit on a cold surface. The wind takes your body heat through convection. But you can insulate yourself from both types of heat loss by wearing layers. Your base layer – think long underwear and thick, wool socks – ensures that you don't lose heat through conduction. And wearing an external, wind and waterproof yet breathable layer protects you from heat loss through convection.
2. Stop shivering
Think of shivering as a warning sign that you need to move to a warm place quickly. When your skin temperature drops, it starts shivering to keep your core temperature from dropping as well. The spasmodic contraction and relaxation of your muscles “uses calories and generates heat” to replace the heat your body loses through convection or conduction. But that means that “once you start shivering, your brain tells your body it's time to go somewhere where you get warmer.
3. Cook up a good meal
Being well-nourished – meaning consuming more calories than you burn – will help your body cope better with the cold. This is very important, to keep your blood sugar levels high enough to provide the energy you need to stay warm in a cold situation.
Staying hydrated is also key. Your body tolerates the cold much better if the food and water balance is maintained.
4. Get used to it
You can acclimate yourself to cold weather. People who spend a lot of time outdoors and in the cold can actually lower their 'set point' before reacting to the cold. The mechanism by which this reset occurs isn't fully understood, but a type of body fat called brown fat may play a role, recent research suggests. Unlike regular "white" body fat, which stores extra calories, brown fat actually consumes calories and releases the energy as heat. Newborns and hibernating mammals have a lot of brown fat, which is thought to produce heat in animals that cannot shiver. And studies in animals and humans have shown that cold acclimation increases the heat-generating capacity of the brown fat. Some research also suggests that exposure to cold actually increases the amount of brown fat in the body. Being physically fit also makes it easier for people to deal with the cold. But being too thin can be a disadvantage, because body fat keeps you warm.
5. Be prepared, all the time
Be aware of weather warnings and fill your car with water, high calorie foods, warm blankets and extra sets of dry clothes just in case.
6. Know your risks
Medicines to treat high blood pressure can make you more sensitive to the cold, as can certain medical conditions, such as an underactive thyroid. Age also affects the cold coupling mechanisms of the human body. Children under 2 have not developed the ability to shiver to raise their body temperature, and people over 60 are less able to generate shivering heat.
7. Skip the booze
Sure, a hot drink with alcohol sounds like something to keep you warm on a bitter day. While a hot drink does indeed raise your core temperature and help you withstand a chill, don't. Alcohol is definitely the worst thing anyone could consume if they are already cold. It lowers the core temperature of the body.
