We may not be fat just because we eat poorly, or too much, or because we don’t exercise enough, but because we turn our heaters too high.

I’ve suspected there’s a downside to too much “comfort” for some time now, that not only our earth, but our bodies, suffer when we substitute driving for walking, supermarkets for gardening and now it seems, perhaps even heaters for sweaters.

New discoveries re: a fat-burning fat

It has to do with brown fat, a type of fat that helps us stay warm by burning a lot of calories to generate heat. Babies, since they can’t shiver very well to stay warm, have it all down their back. And new findings have shown that even as adults most of us have it on our upper back, side of the neck, between the collarbone and shoulder, and along the spine.

This fat acts as our cellular furnace and new research shows that brown fat “can burn huge numbers of calories when activated by the cold, as when sitting in a chilly room that is between 61 and 66 degrees”.

One of the newly released studies on the topic involved 24 men: 10 lean and the rest overweight or obsese. As the New York Times summarized it: “The scans showed no brown fat when the men had been in a room that was a comfortable temperature. But after they were in a chilly room for two hours, scans showed brown fat in all but one, an obese man.”

Are we too comfortable to be thin?

While there are no clear studies of weight loss for people who live in colder climes, or without heaters, that seems to be the next step. Researchers have already found that mice predisposed to obesity when put in a cold room for a week activated their brown fat and lost weight (even while eating a high fat diet).

There are still unknown about this calorie-burning fat, but researchers are already hinting at future implications.

Dr. Francesco Celi, of the National Institute of Diabetes and Digestive and Kidney Diseases argues we should tap into our “natural” fat burning potential: “Turn down the heat and burn calories (and reduce the carbon footprint in the process).”

And one brown fat researcher, molecular genetics professor Leslie Kozak, joked: “We’re thinking of opening a frosty spa”.

So now I have a euphemism for our chilly wintertime Barcelona apartment. The recipe for our “frosty spa”: instead of heaters, we use sweaters, hats, long underwear and wool socks.

Have we lost weight? Well, we do seem to eat more in winter and none of us have gained weight.

How to create your own frosty spa* (to lose weight and save money)

If that’s not enough scientific evidence for you, how about a continent-wide study: Europeans set their thermostats lower than in America and their rates of obesity are much lower. I’ve heard a recommended temperature here of 18°C (64.4°F)- within the brown fat range- while in America it’s often suggested to keep it set at 68°F (20°C), much too high to stimulate your fat-burning fat.

There’s not much time left this year, but to create your own frosty spa for 2010, simply turn down your thermostat to 65°F (18°C) or below, the lower you go the more you could burn.

*Note: there is nothing scientific about this advice, but I guarantee it’s the cheapest spa you’ll ever attend.