Shivering due to cold may have the added benefit of burning body fat, a new study has found.
The study, which determined the role of hormones in regulating how humans respond to cold, showed that shivering caused the body to secrete hormones that transform ordinary white fat into fat-burning brown fat.
"Unlike ordinary white fat, which primarily stores excess calories, brown fat may actually help the body burn calories when activated," said Paul Lee, a University of Queensland researcher who led the study.
Healthy volunteers were exposed to cold temperatures until they shivered and researchers collected blood samples during cooling to measure levels of different hormones.
"We found that the hormones irisin and FGF21 were released when the subjects grew cold, irisin from shivering muscle and FGF21 from activated brown fat," said Lee, also a visiting fellow at the National Institutes of Health (NIH) in the United States.
The team then treated human white fat cells with the two hormones in the laboratory and observed that treated fat cells took on the characteristics of heat-producing and energy- burning brown fat cells.
Previous studies have shown that people who are lean tend to have more brown fat than people who are overweight.
"Further research will establish whether these two hormones may be targeted to help the body produce more brown fat, which may benefit metabolism and weight control," Lee said.