"But there is certainly evidence in people as well as rodents to suggest that reducing temperature makes the body burn more calories to keep up body temperature," said Lazar, who was not involved in the new study.
So how much time sitting in a chilly room would it take to burn, say, 100 calories? It's too early to know, said van Marken Lichtenbelt.
"We do have clear evidence that cold adaptation increases energy expenditure," he said. "There is no doubt in this respect. How pronounced these effects are in everyday life, especially in the long term, is not yet known."
The researchers are planning long-term experiments that involve having people live in cooler environments while tracking their weight over time. "We will vary indoor temperature and weight, and many other health parameters will be monitored," van Marken Lichtenbelt said.
"The other experiment ... is 'cold-temperature training,' also known as 'acclimatization,'" van Marken Lichtenbelt said. "This has been shown to rev up brown fat in rodents, and it seems possible that it could do the same in people."
"It would be very interesting to do something like this in people who are dieting and exercising to lose weight, to see if this strategy could increase the weight loss or even allow the diet and exercise plan to work," van Marken Lichtenbelt said. "We know that so many people struggle with diet and exercise alone."
Is it worth turning down the thermostat if you're trying to shed some pounds? It's too soon to be certain that strategy would work, said Lazar, who also is the director of the University of Pennsylvania's Institute for Diabetes, Obesity and Metabolism.
"It would do no harm," he said. "It's worth a try for someone who is having trouble losing weight by diet and exercise alone."