I personally do not allow anyone to do road work in a sauna suit. The risk of over heating, and becoming dehydrated is to great. I will add that I do not live in a extreme cold climate, so if you are in Alaska or Canada in the winter, probably be no problem. But when you are around temperatures of 50 and above, I have seen people work out in them and after awhile, they are over in the locker room coming out of them. Water loss is a tricky thing. I would suggest you talk with a professional trainer in your gym Water loss is not a simple matter. Your body needs it, and when you excessively sweat it out, you have a tendency for thirst to force you to replinish your fluids, and you gain little if nothing.