Changes in ambient temperature found to influence brown fat levels
By Nick Lavars
July 1, 2014
The discovery that lowering your body temperature leads to an increase in a certain type of "good" fat might have some ditching the diet books and shedding a layer of clothing instead. A study conducted at the National Institute of Health (NIH) in Washington has demonstrated that changes in ambient temperature affects brown fat levels in humans, pointing to potential treatment options for the weight-wary and sufferers of diabetes.
Unlike white fat, which stores calories, brown fat generates energy and warmth by burning the calorie-storing white fat. It therefore has an important role to play in fending off obesity. While the difference between the two forms of fat, or adipose tissue, has been known for some time, how brown fat can be regulated in people hasn't been quite so clear.
The knowledge that higher concentrations of brown fat can help to fight off obesity has seen research efforts focus on how, if at all, its levels could be regulated. In 2012, scientists found that commonly prescribed Type-2 diabetes drugs TZDs promoted conversion of white cells into brown. Soon after, it was discovered that certain proteins made by the body regulate the development of brown fat and could provide a therapeutic target in the fight against obesity.
The latest study, with the appropriate acronym of ICEMAN (Impact of Chronic Cold Exposure in Humans, was led by endocrinologist Dr Paul Lee from Sydney's Garvan Institute of Medical Research and involved monitoring the fat levels and metabolic changes in five healthy men across four month-long sessions at various temperatures.
During the sessions, the participants went about their daily routines, but spent each night in a temperature regulated room at NIH. For the first month the temperature was set at 24° C (75° F). This was chosen as it is "thermo-neutral" and doesn't require the body to work to regulate its temperature. Measurements taken at the end of the first month were noted as baseline figures.
For the second month-long session, the temperature was dropped to 19° C (66° F), raised back up to 24° C for the third, and then cranked up to a toasty 27° C (80° F) for the fourth and final stint.
The researchers found that brown fat levels were increased during the cooler month and then fell in the warm month. Furthermore, they observed a metabolic benefit for diabetics in that a higher brown fat level led to increased insulin sensitivity, indicating those with more brown fat cells may not require as much insulin to bring their blood sugar level down after a meal.
"The improvement in insulin sensitivity accompanying brown fat gain may open new avenues in the treatment of impaired glucose metabolism in the future," says Lee.
The news isn't all good, however, with the research also suggesting our penchant for climate controlled living may be linked to rising obesity levels in certain parts of the world.
"On the other hand, the reduction in mild cold exposure from widespread central heating in contemporary society may impair brown fat function and may be a hidden contributor to obesity and metabolic disorders", he says.
The team's research findings were published in the journal diabetes.
Source: Garvan Institute