Could shivering in the cold be a way to shed pounds and possibly prevent diabetes?
Exposure to cold is the most well-known and well-studied mechanism for switching on energy-burning brown fat, which seems to protect mice from developing obesity. It remains to be seen whether the same process can help people.
Humans have three kinds of fat. White adipose tissue, or white fat, comprises the majority of fat in our bodies; its purpose is to store energy for future use. Brown fat is different: Its function is to generate heat to maintain body temperature. Until recently, it was thought that adults did not have brown fat, that it only existed in babies to help them stay warm before they could move around and then essentially vanished. But beginning in 2009, studies have found that many adults have brown fat and that people with more of it tend to be leaner and have lower blood sugar levels.
The third kind of fat, beige fat, appears to convert from white to brown when stressed by exposure to cold, and then back to white. This process is encouraging for scientists trying to figure out how to increase brown fat to improve healthy functioning of the body.
“A balanced diet and regular exercise are the cornerstones of healthy metabolism, but sustaining either is difficult for most people. Understanding how brown fat could benefit our health opens up a new direction in obesity research,” says Paul Lee, an endocrinologist at the Garvan Institute of Medical Research in Sydney, where he leads the Brown Fat Physiology Group. “It is not a solution to obesity, but it is an opportunity to explore an alternative strategy for curbing the obesity epidemic.”
When the body senses cold, Lee says, the brain releases norepinephrine, a chemical that essentially ignites the fat-burning process within brown fat. When there is not enough brown fat, the body has to turn to less-efficient heat-generating models, such as…