If you are a human in winter today, take solace in the knowledge that being outside burns calories. In the journal Trends in Endocrinology and Metabolism, scientists from Maastricht University in The Netherlands argue that when exercise isn't an option, "regular exposure to mild cold may provide a healthy and sustainable alternative strategy for increasing energy expenditure."
Shivering can increase your metabolic rate as much as five fold. The problem with shivering is that it is terrible, so Dr. Wouter van Marken Lichtenbelt and colleagues looked into being only mildly cold as a way to burn calories. Our bodies burn energy to keep us warm in a process called non-shivering thermogenesis (NST), they explain, which works even at pretty reasonable temperatures. They defined mild cold exposure as 64 degrees Fahrenheit.
"In most young and middle-aged people NST increases by between a few percent and 30 percent in response to mild cold exposure," they write. They say that can significantly improve your calorie-in to calorie-burned ratio. Even if you eat more to compensate, most people won't eat enough to undo the extra expenditure.
"Indoor temperature in most buildings is regulated to minimize the percentage of people dissatisfied," they note, apparently in reference to some ideal world that is not our office. "By lack of exposure to a varied ambient temperature, whole populations may be prone to develop diseases like obesity. In addition, people become vulnerable to sudden changes in ambient temperature."