I'm wondering if anyone else out there does this. The idea is to keep your body in cold surroundings as much as possible so it has to burn more calories in order to maintain the constant body temperature. If you have taken a chemistry class and understand thermodynamics, you know that the only way to create heat is to transfer energy (by burning calories). Anyways, I have gotten in the habbit of making my self as least warm as possible throughout my day. For example, I always wear a T-shirt and shorts no matter how cold it is. My body ajusts it's metabolism and burns more calories to compensate. There is always proof of this adaptation: for example, in cold weather I stand perfectly comfortable next to someone who is shivering in their sweatshirt and long pants. -The Columbia Electronic Encyclopedia, Sixth Edition I'm sure many of you will be refuting me right now by thinking I'm an idiot because "being cold like that will get you sick for sure!". I am surprised at how much I hear that myth. Being cold does NOT make you sick! Viruses and bacteria do. -http://www.mindspring.com/~drwarren/uri.htm (and MANY other websites..) Do this all within reason of course. I live in California so it never gets colder than high 40's. Of course it would be unhealthy to take yourself near the point of hypothermia, but you get the idea.