(LONDON) -- While a warm, toasty house may feel great in the winter, some researchers suggest warm temperatures also may play a role in the obesity epidemic.
Fiona Johnson of University College London and her colleagues analyzed a number of studies that examined the relationship between exposure to cold temperatures and the ability to burn off energy. Their research is published in the journal Obesity Reviews.
They found evidence that over the past several decades, people in the U.S. and the U.K. have been steadily raising the temperatures in their homes.
They also found indirect evidence that the body's response to cold, which consists of shivering and hormonal actions, plays a major role in energy expenditure. Regulation of body temperature, they say, is associated with weight.
But some weight loss experts said the connection between cold temperatures and weight isn't yet very strong and they can't say for certain whether there's any association with obesity.
Experts do agree that one of the study's findings raises interesting questions about the role of a type of tissue that previously received little attention. The authors found that brown adipose tissue, a kind of fat, plays a very significant role in burning energy when exposed to cold.
Dr. Jana Klauer, a physician in private practice in New York, said small animals and babies have brown adipose tissue, but as people get older, they tend to lose it. Studies have shown, however, that some adults do have it, though it hasn't been determined how common it is.
Klauer cited a recent study done in Japan that exposed two groups of men to cold. One group had brown adipose tissue and the other didn't.
"They found that in people that had the brown fat, energy expenditure went up 400 more calories per day when they were exposed to cold," said Klauer. "They were using 400 more calories to generate heat."
The results suggest that weight loss in cold temperatures may be easier for people with brown adipose tissue.
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