We are all born with supplies of brown fat around our necks, nature’s way of helping to keep us warm as infants. Until only a few years ago, it was thought to vanish in early infancy, but we now know that brown fat is present in most, if not all, adults. Adults with more brown fat are slimmer than those without.
A new study suggests that shivering and bouts of moderate exercise are equally capable of stimulating the conversion of energy-storing ‘white fat’ into energy-burning ‘brown fat’.
Around 50 g of white fat stores more than 300 kilocalories of energy. The same amount of brown fat could burn up to 300 kilocalories a day.
Endocrinologist Dr Paul Lee, from Sydney’s Garvan Institute of Medical Research, recently undertook the study at the National Institutes of Health (NIH) in Washington*, funded as an NHMRC Early Career Research Fellow.
His work uncovered a way that fat and muscle communicate with each other through specific hormones – turning white fat cells into brown fat cells to protect us against cold.
Dr Lee showed that during cold exposure and exercise, levels of the hormone irisin (produced by muscle) and FGF21 (produced by brown fat) rose. Specifically, around 10-15 minutes of shivering resulted in equivalent rises in…
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