It is minus 12 C (3°F) outside and I have just returned from a walk in the beautiful but cold sunshine. So this is the perfect time to discuss a little known benefit of cold weather. If weight loss is your goal, I have some good news for you. Research shows, if we spend our time in colder temperatures, we can burn more of the fat stored in our bodies, including from our key reservoir of body fat, our butts. That is right… you can freeze your butt off.
There have been several studies that discuss how being cold stimulates weight loss. However, there is a catch – your body must be able to adjust to the cold in order to keep you warm. This is called non-shivering thermogenesis. If you start to shiver – you are too cold.
We have two types of fat: white fat and brown fat. Our brown fat levels decrease as we age to about 1% as adults. Brown fat helps convert white fat or storage fat to energy (glucose) and in effect, promotes thermogenesis which is how our bodies produce heat and burn calories. A person can lose weight if the body is using this method to stay warm. Unlike other methods of increasing thermogenesis, there is no increase in appetite which is often experienced during high-intensity exercise, another way to increase thermogenesis. Non-shivering thermogenesis converts white fat for energy and heat, so we do not need to consume more food to stay warm.
So how cold do you have to be? Well, here is the good news. You do not actually have to go outside into the freezing cold. A 1980 study, featuring nine women, measured heat loss and heat expenditure for a 30 hour period on two occasions, one with the ambient temperature at 22°C (71°F) and the other at 28°C (82°F. All participants had a pre-determined food intake and activity level. The results showed a greater resting metabolism rate at 22°C than at 28°C or in other words, participants were burning more calories when the ambient temperature was lower. So turn down your thermostats. It doesn’t get any easier than that.
A 2011 article in the New York Times cited a paper from British researchers who argue that rising indoor temperatures are contributing to obesity. In 1968, British living rooms were kept at an average temperature of 64.9°F (18°C) and 59°F (15°C) for the bedrooms at night. By 1996, the living rooms were on average 70.3°F (21°C) and bedrooms at night were 64.3°F (17°C). Similar data in the North America also show an increase in household temperatures, if not even higher.
People also now heat their whole house whereas in the past they would only heat the living rooms and kitchen during the day and their bedrooms would be cold at night. This means that today the body temperature does not have to adjust when we go from room to room and therefore, non-shivering thermogenesis does not kick in to allow them to burn more calories. This is an interesting theory, but if the idea of lowering the house temperature is not appealing, other studies have indicated that these results can also be achieved by exposure for short periods to very cold temperatures. So, go for a walk outside. Get as cold as you can handle while still enjoying the experience. If you start to get too cold, jump up and down or walk more quickly. Your ability to warm up is non-shivering thermogenesis at work.
Unfortunately, there is one problem with this method of weight loss. Our brown fat levels decline as we age and with its decline, the ability to burn calories to stay warm goes with it. It is important to maintain our brown fat levels. A deficiency in carnitine can result in lower brown fat levels and studies show increasing carnitine in the diet can increase it. High levels of carnitine can be found in beef, dairy products, chicken and codfish as well as lower levels in some vegetables such as asparagus broccoli, kale, Swiss chard, nuts and seeds, grains such as whole wheat, corn and millet. Brewer’s yeast and bee pollen are also good sources of carnitine as well as fruits such as bananas and apricots.
Corticosteroids deplete brown fat levels and inhibit non-shivering thermogenesis so this may explain weight gain in those who take these medications.
There is more. Noradrenaline, the opposite of adrenaline, is helpful in the function of brown fat. In other words, brown fat functions best when stress levels are low. There is also a direct link between those who secrete more cortisol, a decrease in brown fat levels and thermogenesis function and a greater tendency to obesity. Since limiting stress aids the maintenance of brown fat, be sure to make time for yourself and take time to practice relaxation techniques. If you do nothing else, breathe deeply as often as you can, while you are driving in the car, before you go sleep at night and any other time you think of doing it. Just breathe and relax. This will help you lower cortisol levels especially if you can stop thinking about what is stressing you out while you are doing all this breathing.
To warm up after a walk in the cold, try this delicious Red Lentil, Apple and Sweet Potato Soup
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