We’re facing another bitterly cold day here in Minnesota. Temperatures in the Twin Cities are not expected to rise above zero.
But don’t go cranking up your thermostat too high today. For allowing indoor temperatures to stay mildly chilly — say, around 60 degrees F — may help boost weight loss, according to a paper published Wednesday in the journal Trends in Endocrinology & Metabolism.
In the paper, three Dutch researchers, including Wouter van Marken Lichtenbelt of Maastricht University, make the provocative argument that living with more variable indoor temperatures — ones that reflect the changing temperatures outside — could significantly increase our energy expenditure and thus, potentially, decrease our waistlines.
Most research on temperature and health has tended to focus on the effects of extreme cold and heat. But “since most of us are exposed to indoor conditions 90 percent of the time, it is worth exploring health aspects of ambient temperatures,” said Lichtenbelt in a press statement released with the study.
“What would it mean,” he added, “if we let our bodies work again to control body temperature?”
Two types of shivering responses
When we are exposed to cold, we, of course, start shivering. This natural response (known technically as shivering thermogenesis) helps ward off hypothermia by expending energy (calories), which produces internal heat. Shivering can increase the body’s metabolic rate by up to five times its normal rate, studies have found.
Of course, no one would advocate standing out in the cold and shivering as a method of weight control. But, as Lichtenbelt and his colleagues point out in their paper, research has also shown that our bodies react to cold, including mild cold, with another — and much more comfortable — heat-generating process known as nonshivering thermogenesis.
Interestingly, nonshivering thermogenesis appears to be associated with brown fat, a type of adipose (fat) tissue that burns calories rather than storing them.
When young and middle-aged adults are exposed to mildly cold temperatures, nonshivering thermogenesis increases by up to 30 percent, thus having a potentially significant effect upon the amount of energy they expend. (For age-related metabolic reasons, elderly people tend to have a lesser nonshivering response to mild cold, according to the Dutch researchers.)
Lichtenbelt and his colleagues suggest that, “in parallel to physical exercise, one should promote temperature training as part of a healthy lifestyle.”
A Japanese study, they point out, found that a two-hour daily exposure to temperatures of around 62 degrees F resulted in a significant decrease in body fat mass at the end of six weeks.
In their own lab, Lichtenbelt and his colleagues have shown that exposing people to temperatures of 59 to 60 degrees F for six hours a day activated more brown fat. By the end of the 10-day study, the participants had also acclimated to the colder-than-normal indoor temperatures, including shivering less.
One factor to consider
“Indoor temperature in most buildings is regulated to minimize the percentage of people dissatisfied,” the researchers write. “… This results in relatively high indoor temperatures in wintertime. This is evident in offices and in dwellings, and is most pronounced in care centers and hospitals. By lack of exposure to a varied ambient temperature, entire populations may be prone to develop diseases like obesity.”
“More frequent cold exposure alone will not save the world,” they add, “but is a serious factor to consider in creating a sustainable environment together with a healthy lifestyle.”
You can read the study in full on the Trends in Endocrinology and Metabolism website. (And, yes, regular readers, I’ve pointed out some of this research before, most notably last fall.)