The winter in England can drag on for so long. Dull depressing day after dull depressing day, but good news! Cold temperatures may aid weight loss. Shivering for just 15 minutes provides the metabolic equivalent of 1 hour of moderate exercise.
Shivering is a short term biological response to cold temperatures; it is a defence against hypothermia and aims to maintain core warmth to protect vital organs. Until recently it was believed infants had both white and brown fat but adults only had the former. It is now thought that adults do have brown fat but in varying quantities; slimmer individuals seem to have more brown fat and less white fat. Brown fat appears to be the fat that provides warmth.
The Cell Metabolism Journal has published a new study from the U.S National Institute of Health led by Dr Francesco Celi, chair of the Division of Endocrinology and Metabolism at the Virginia Commonwealth University School of Medicine. The researchers used 10 healthy male and female participants and asked them to exercise for an hour in an 18˚c laboratory. Later they were told to lie on beds in a room of 12˚c. Their data revealed that in both situations the participants muscles contracted and their bodies produced the hormone irisin to raise body temperature and burn brown fat.
A Japanese study found shivering for 2 hours a day over a 6 week period noticeably decreased people’s body fat percentage. Other studies have suggested that shivering raises the metabolic rate by 30%, therefore shivering has the potential to burn 400 calories in an hour.
But before you go running out into the cold in only your underwear, Dr Paul Lee from Sydney University has said “it’s true that one will burn more energy [shivering] but it’s also a stress response”. The key is to only expose yourself to occasional mild cold, not extreme low temperatures that pose a threat to your health. The odd shivering session may be beneficial, experts believe we spent too many hours indoors with heating and sometimes we need to get our metabolism going and burning fat rather than storing it.
We must also say that shivering should not be your entire exercise regime. It doesn’t boast anywhere near as many health benefits as physical exercise. But next time you complain about being cold just think you are burning fat!