Humans are capable of growing new ‘‘baby fat’’ that could actually help them lose weight and become healthier, a study has found.
Australian and US researchers have been able to grow the fat in volunteers, simply by exposing them to cool temperatures every night for a month.
They believe our bodies’ quest to regulate temperature could be a hidden key to explaining the rise in overweight and obesity across the developed world, as our ‘’good’’ fat has wasted away because of a lack of exposure to cooler temperatures.
”Most of the fat we have in our bodies is white fat, and when we have too much of it we develop conditions like obesity and diabetes,” said Paul Lee, the lead investigator on the study. ”In contrast this fat, which we call brown fat, is a specific kind of fat that actually burns energy and releases it as heat.”
He said it was estimated about 60 grams of brown fat, if activated by cold, would burn 4.5.kilograms of white fat over the course of a year.
For many years it was believed that humans shed their brown fat by the time they reached adulthood, until scientists using positron emission tomography scanners discovered some adults had reserves, and they tended to be slimmer and healthier than those who didn’t.
Dr Lee, an endocrinologist and clinical research fellow at the Garvan Institute in Sydney, said researchers had realised that if brown fat could be harnessed, it could be used to provide significant health benefits.
In his study he recruited five healthy men to spend every night for four months in a temperature-controlled lab.
”We know brown fat can only be activated in the cold, because if the body is in a temperature-controlled environment it doesn’t need to burn energy to produce heat,” he said.
The group were slowly acclimatised to lower temperatures, to allow those without brown fat to grow it, before being kept each night in a 19 degree Celsius room that keep them cool but not shivering.
In just one month their brown fat was able to grow by 40 per cent and their insulin sensitivity (a measure of healthy metabolism) improved.
But when they were kept in a 27 degree room, the fat disappeared again.
Dr Lee said he wondered whether our modern obsession with always being in temperature-controlled environments was contributing to the modern obesity epidemic.
”We always think about how food is essential to survival, and it is, but the body is also always trying to protect the core temperature as well,” he said. ”Today we never need to produce more heat to keep us warm.”
He is now trying to develop drugs that could produce the same response.
”If it was able to occur naturally that would be good, but cold exposure is a bit like exercise, so we can’t necessarily expect someone who is not used to cold to expose themselves to it, and it might not always be safe.”
The research was published overnight Australian time in the journal Diabetes, as well as being presented at the International Society of Endocrinology and the Endocrine Society in Chicago.