Actually, you need to be fit in order to stay active while in a dehydrated state.<quoted text>
Water loss is not an attribute of good health, other than degradation of kidneys and chapped lips. And no mention of muscle mass buildup, so your post has no viable information to enlighten us. Go back to school, and progress beyond the 5th grade graduate diploma that most rednecks proudly hang on their wall.
I suggest you go outside one day when it is extremely hot and not drink any fluids, drive a car at 180+ mph for 4 hours and see how you feel.