Naked, I'm sorry. But... your information is very flawed and very inaccurate. The human body can fall hypothermic (body temp below 95.5) in 50 degree weather. It's easily avoidable in anything above freezing, but to say the body automatically adjusts is... well, wrong.
*BUZZZ* Thanks for playing, but I'm afraid the answer is: mammals, such as we, are warmblooded, and therefore are able to automatically regulate their internal body temperature through their own metabolic system, and can thus sustain a fairly constant body temp, despite their external environment. This is why I can comfortably run around all night in 45 degree weather wearing nothing but boxers and boots, ie last year when I got stripped on a walk-about.
My friend, you may be a damn fine EMT, but biology is my thing.