I picked these up for running in winter to wear under my shorts so blind drivers could see me. I'm 6'1 230lbs with a 38" waist and the XL are more form fitting than compression. I might need to go down to the large size to get actual compression out of them. I'm not certain if they will keep me warm in -30C, but they should work at -20C. I'll update my review once I've had a chance to wear them in some real cold, as it's only November and winter has just started.