Brown adipose tissue (called brown fat) helps babies, young children, and other small mammals stay warm by burning calories when activated by low temperatures. Scientists have been skeptical that 
adults retain significant amounts of brown fat on their bodies. But the new research shows that many of us -- perhaps even most – do Cypess and his team also found that people whose scans were done in the winter had the most brown fat, while those scanned in the summer had the least; people who underwent the tests in the spring or fall fell in the middle.
And this:
Using PET to examine how cold temperatures affected brown fat activity, this time in five people. Participants spent two hours in a room kept at 63° F to 66° F. During the scan, they submerged one foot in ice water, alternating five minutes in the water and five minutes out. The cold conditions boosted the amount of glucose the study participants' brown fat consumed by a factor of 15.
The article concludes with this:
The maximum amount of extra energy that people with relatively large brown fat deposits can burn probably tops out at about 500 calories. "It doesn't take much extra food to eliminate any benefit you've got," he said. "I personally don't think that hanging out in the cold is going to be an effective way of fighting obesity."
Turn down the heat and walk around the house nekkid. Sounds like a plan. It tops out at 500 calories, and you have to spend the day in the cold. Maybe a little less food and a little more exercise would be a better choice.
