Cold weather has an upside: New research suggests that spending time outside when the temperature dips could increase brown fat, which triggers your body to burn more fat and keep your warm.
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I spent the first 30 years of my life in Canada, so as you can imagine, I’ve braved my share of cold weather days. But watching CNN this morning, I can truly empathize with those of you freezing your butts off on the East Coast this week.
As you bundle up in your stocking hat, fur-lined gloves, fleece jacket, puffy vest, insulated boots and any other winter gear that makes you look like the Michelin Man, take comfort in this: cold weather has an upside. We’ll get to that shortly, but first I want to tell you about some hot-off-the-press research:
A “New” Protein Discovered
Scientists at the University of California-Berkeley report that they’ve discovered a protein that can increase the production of “brown fat.” What is “brown fat” and why is that good news? Scientists have known for years that there are two kinds of body fat: what’s called “brown fat” and what’s called “white fat.” The former triggers your body to burn its own fat to keep you warm, the latter encourages the storage of body fat. On average, about 90% of our body fat is the white kind, which is obviously far from ideal in terms of weight management. We want to burn, baby, burn—not store—fat.
Back to this new protein. Working with mouse embryos, the Berkeley researchers discovered that when they raised the level of the protein (known as transcription factor Zfp516) to which the embryos were exposed, baby mice were born with higher amounts of brown fat. What raised the level of the protein? Exposure to cold air—and the more exposure to cold, the greater the production of brown fat. When the same researchers disabled the gene for the Zfp516 protein, the mouse embryos did not produce any brown fat.
When all the baby mice were fed the same high-fat diet, mice with no Zfp516 became obese, while those with the protein gained far less weight. Increased levels of Zfp516 also appeared to enable white fat to burn calories as brown fat does. The researchers hope that their these findings will one day lead to a treatment based on this protein, which could “signal” human genes to transform white fat to brown fat. This could speed up metabolism and result in weight loss. But that possibility is a long way off.
Lower Temperature, Lower Weight
So what can we do with this knowledge at this time? In the days before central heating, people simply tolerated chilly temperatures for part of the year. Their ratio of brown and white fat varied with the season. They needed more brown fat when temperature dropped so their body fat could self-regulate body temperature in cold conditions.
Today, air conditioning and radiators have narrowed what we regard as a comfortable temperature range within our homes. Why subject yourself to cold (or heat) if you can just adjust the thermostat? We also spend more time indoors, both for work and entertainment, than previous generations did. As a result, we have less brown fat and more white fat than our grandparents and great-grandparents, which is yet another reason why we tend to be heavier than they were.
Go for the Brown
To remain slim or reduce your weight, you want to increase the ratio of brown fat to white fat by encouraging the conversion of metabolically inactive white fat to metabolically active brown fat. And one of the ways to do that is to spend time outside when the thermometer dips.
Simply being outdoors in the cold air enables your body to burn more calories as it makes an effort to warm your body. Surely you’ve noticed that when you’re chilled, you shiver and shake, which is your body’s way of warming itself by increasing its resting metabolic rate. One study found that spending time outdoors in cold weather can increase the number of calories burned by as much as 30%. And the more time you spend in cool temperatures, the more you can tolerate the cold and the less you shiver. How come? Your body has more brown fat.
Do you have to venture out in subzero temperatures to increase your ratio of brown fat? Fortunately, the answer is no. Dutch researchers have studied what they call “non-shivering thermogenesis” and found that even milder cold temperatures, say 55° Fahrenheit, can raise your resting metabolic rate so that you burn additional calories. Another study revealed that spending just two hours daily at about 63° Fahrenheit for six weeks burned more calories than the same amount of time in a warmer situation.
5 Ways to Chill Out and Slim Down:
1. Spend more time outdoors in cool weather
2. Take up ice-skating, cross-country skiing, snowshoeing, or another cold-weather activity
3. Wear one less layer of clothing—your body will acclimate
4. Turn the thermostat down to no more than 68° Fahrenheit during the day and no more than 63° Fahrenheit at night
5. Drink cold water before a meal
Pasternak is a celebrity trainer and nutrition expert who has worked with stars from Halle Berry and Lady Gaga to Robert Pattinson and Robert Downey Jr. He’s also a New York Times best-selling author, with titles including The Body Reset Diet and The 5-Factor Diet. His new book 5 Pounds hits shelves in March 2015. Tweet him @harleypasternak.