Tricks for staying warm

“No-one is perfect; I myself am susceptible to drafts.” Oscar Wilde

I don’t know about you, but I have been getting cold lately. However when you look around, it seems that there has never been a time when we have been better protected from the cold than we are now. But that in itself is intriguing how did people stay warm in the past? And why do we still get cold?

Obviously people get cold when the temperature drops but if you are healthy, your body will be kept at a steady 36.5–37.5 °C despite the cold. The reason we need to stay at this temperature is that it is the one that our neurons work best at. If your core body temperature gets between 32-35 °C you are hypothermic and will start to see neurological symptoms including confusion. However you are pretty robust and your body has a number of strategies that stop this happening too easily. Not least making you feel uncomfortable so you take action to get warm.

Maintaining body temperature is an active physiological process, so your ability to stay warm when you are in a cool space is by definition a type of fitness. I suppose you could argue that there are two sides two this: there is perceiving the cold and your body’s ability to combat the cold, and they are not quite the same thing.

Who feels the cold?

The old and the young feel the cold. The bad news is that if you are over 60 you will have a reduced ability to contract blood vessels in your extremities. So it is hard for you to shunt blood into your vital organs. This will make it harder for you to maintain a higher “average” blood temperature and that will intern effect your ability to stay warm. Your blood will be getting cold in your arms and legs; whereas when you were younger it would have gone into your torso to get warm, sooner.

Interestingly babies have a lot of brown fat. Babies don’t shiver. They don’t yet have the kind of autonomous control over their bodies that we adults have. Instead they have a lot more Brown fat. This is a type of highly metabolically active fat. It basically warms the babies up by burning through itself. Babies are able to burn fat to produce heat and stay warm that way. Sadly adults don’t have much brown fat so we can’t get thin by simply staying in cold rooms. It turns out that anyone under the age of 14 is also unlikely to be able to shiver, or shunt blood as well to keep warm. So it is important to understand the age of the people in your group and make concessions for those outside of the age range: 14-60. (FYI mum, if you are reading this: I am sorry for being difficult about putting the heating on last time you were at mine. I didn’t know then what I know now)

Other than the old and the young there is also the skinny. 90% of your body heat is lost through your skin. The rest is lost through your breath. The rate at which you lose heat is dictated by your volume to surface area ratio. If you are big, you have a larger volume in proportion to your surface area. So the small will get cold more easily. There have been times when I have been twice my wife’s weight, so it is hardly surprising that some people get cold quicker than others.

Metabolic rate is critical

The heat that comes from your body is the result of calories being burned. The higher your metabolic rate, the higher your burn rate, the more heat you are generating the warmer you will be.

Roughly tent percent of the calories that you consume are turned into heat as a result of the energy required to process the food. Ironically Fatty food doesn’t contribute much to warming you up. On the other hand protein is really good. Up to 35% of the energy contained in protein gets expelled as heat. So if you are cold it may help to increase the amount of protein you take. That doesn’t necessarily mean meat; there are plenty of plant based sources of protein such as peanut butter.

Physical activity is the most obvious way to raze your metabolic rate. It’s a good idea to move about during the day: Animal studies have generally shown that an individual bout of exercise will help you stay warm for the rest of the day, and that regular exercise will also increase your resting metabolic rate, making you better able to cope with the cold, even despite the fact that you might lose your insulating layers of fat. Reff

Clothes help. It’s often said that loose most of your heat through your head. This isn’t actually true. You lose about 25% of your body heat through your head and neck. That is roughly what you would expect, for the highest point on your body and for a part of the body that is that size. However hats do obviously help you stay warm. Dressing properly, is clearly the most cost effective way of staying warm. In fact 25% of hypothermia deaths are the result of people removing clothing. So if you’re cold, stay clothed.

The other problem with not being appropriately dressed, even in doors is that it makes you more susceptible to drafts. Perhaps Oscar Wilde needed to put a few more layers on. I can say from personal experience that one of the best money saving tips is to build yourself secondary glazing. (here) We have old style sash windows. Double glazing is really expensive and the payback time is not great but, there is a much cheaper home grown alternative. Buy acrylic, and magnetic tape, and stick the large sheets of acrylic over your windows, for winter until it’s time to start opening the windows again. We have this. The drafts dramatically reduce and the added bonus is that the road noise is also cut. On the down side, a good gust of wind does sometime blow them off. I was the only person in the house when that happened and got quite a shock.

Finally have a think about how you are losing heat. Some materials are thermal conductors, such as metal. Touching these materials will wick heat away from your body so it is a good idea to put a layer between you and a material that is a thermal conductor. Sometimes this is obvious, put dry gloves on before handling metal tools. Other times it is less so. The best tip we learned this year on wine rides, is to put a blanket between you and the airbed when you are camping. There is large volume of cold air in an airbed. So overnight you lose a lot of body heat into the airbed. If you have blanket, it is better the put it under your sleeping bags as an extra layer of insulated, rather than on top of you. This is because the airbed is conducting heat away from you.

Finally heat the spaces you are in. Some people think it is more cost effective to keep a room warm, rather than let it cool down while you are away. I am reliably informed this isn’t the case. The most cost effective thing to do is heat the room when you are in it. It is also cheaper to keep internal doors closed and only heat the rooms you plan to use. I am a big fan of data, so I also think it is worth knowing the temperature you tend to get to before discomfort sets in. I know for me it I 16.5 C, at that point the heating has to go on. But I also know for some people that would be way to cold. The best thing to do is get your thermostat set up for how you like lit, and for when you are actually in. for me anything above 16.5 °C is easily manageable with all of the above, but any time spent bellow that will result in me needing the heat up for the rest of the day.

If you have any tips not listed above, then get in touch I would over to hear them.

Reffs:

http://en.wikipedia.org/wiki/Thermal_comfort#cite_note-autogenerated16-17

http://www.ncbi.nlm.nih.gov/pubmed/7632602

http://www.ncbi.nlm.nih.gov/pubmed/14692598

https://www.youtube.com/watch?v=RExXwCNP9No

http://greatist.com/health/complete-vegetarian-proteins