When I diet I do a cyclical ketogenic diet - no carbs Monday through Friday, carb up on the weekends. I get my Dexa scans on a Friday morning when I'm at my most dry and depleted for the week. I do it that way because I figured it's the most accurate way to gauge muscle gains.
In my case getting the scan depleted vs. loaded would make quite a difference - for example, I'm dieting right now and carbed up over the weekend and gained 10lbs. from Friday morning to this morning.