Study suggests metabolism changes with the seasons
Monday, June 23, 2014, 3:57 PM - A new study by the Garvan Institute in Sydney, Australia suggests that cool environments stimulate the growth of brown fat in people while warm environments promote fat loss.
The study, which was presented Monday at an international conference in Chicago, sheds some light on how brown fat is regulated in the human body -- a concept that has remained largely unclear.
Brown fat is a type of fat found in the human body that burns energy to generate heat.
In the small-scale study, five healthy men were exposed to four month-long periods of temperature fluctuations, spending at least 10 hours a night in a climate-controlled room.
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For the first month the rooms were set to 24 degrees Celsius. That was changed to 19ºC the second month, back to 24ºC the third and then up to 27ºC for the fourth month.
"The big unknown until this study was whether or not we could actually manipulate brown fat to grow and shrink in a human being," Dr. Paul Lee, an author in the study, said in a statement.
"What we found was that the cold month increased brown fat by around 30-40 [percent]. During the second thermo-neutral month at 24 degrees, the brown fat dropped back, returning to baseline. When we put the temperature up to 27 degrees during the fourth month, the volume of brown fat fell to below that of baseline.”
Researchers say the findings could pave the way to better treatments for people suffering with diabetes, because brown fat gain leads to an improvement in insulin sensitivity.
"Studies have been performed in the UK and US measuring bedroom, dining room and lounge room temperatures in people’s homes over the last few decades, and the temperature has climbed from about 19 to 22, a range sufficient to quieten down brown fat," Dr. Lee says.
"So in addition to unhealthy diet and physical inactivity, it is tempting to speculate that the subtle shift in temperature exposure could be a contributing factor to the rise in obesity."
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