Spending time in cooler temperatures can boost calorie burn by up to 30%, according to research in the journal Trends in Endocrinology and Metabolism. For this, you can thank brown fat: The opposite of unhealthy white fat, brown fat is a good type of fat that actually helps the body burn energy in the form of heat. Over time, spending several hours a day in chilly temps increases the amount of brown fat in the body, causing people to feel more comfortable in the cold and shiver less—but still burn plenty of calories in an attempt to keep warm.  Fortunately, you don’t have to withstand blizzard conditions to up your body’s production of brown fat. Experts have long known that shivering in response to very cold temperatures causes an uptick in the body’s resting metabolic rate as it tries to keep warm. But more recently, it’s been found that mild cold temperatures can ramp up the body’s energy expenditure, too, says study author Wouter van Marken Lichtenbelt of Maastricht University in the Netherlands.  In fact, you may be able to start reaping the benefits by simply lowering your home’s thermostat. The average person spends about 90% of the time indoors, where temperatures tend to hover at a balmy 70° F. But according to a recent study in The Journal of Clinical Investigation, people who spend two hours a day in mild cold (around 63° F) for six weeks burned more energy than people who spent the time in warmer temperatures. Bottom line: bring on the polar vortex—or at least one less layer of clothes. More from Prevention: Three Walking Workouts For The Winter Months