When super lean, i always sleep with sweat pants, sweater etc in the winter, or else it's just to cold..When super cold i use a space heater, and sometimes socks..Many things that Johhny already suggested. When you have no fat in the winter you have to do what you have to do. I thought that there was something wrong with me until i spoke with Johhnynoname about the subject.
No patience make sure your body temperature is normal..Low body temperatures can be a bad sign...
But yes, you only really figure out what the fat is for after you lost it all and are always cold. I was never really that fat, My abs have alway stayed visible while bulking..