In a first, researchers have documented that cold temperatures may encourage 'unhealthy' white fat to change into "healthy" brown fat. The study indicated that about 30 percent of cells that appear to be white fat can rapidly turn on the brown fat following cold stress. "Fat cells can adopt a range of metabolic phenotypes, depending on physiological conditions and location in the body," said James G. Granneman, a researcher involved in the work from the Center for Integrative Metabolic and Endocrine Research at the Wayne State University School of Medicine.

http://news.vocus.com/?a=20048754640&p=19f&v=1&x=6e8yGDJSbsIAAqV0q0m1Cw
http://www.thehealthsite.com/news/cold-weather-may-encourage-healthy-fat-formation/
http://www.sciencecodex.com/exposure_to_cold_reveals_the_switch_that_controls_the_formation_of_brown_and_white_fat-148248