Research carb loading. It sounds like, and given the evidence of you being a picture-less, and too lazy to complete a profile, that you have a number of underlying issues.
6.6 pounds is NOTHING. You can drop 4 pounds going to the bathroom.
Carb loading / glycogen loading can make your weight bounce by as much as 15 pounds in a day.
You have way, way, way, way, too much time on your hands and have some screwed up priorities if you're worried about a 6 pound load once you start eating. That's normal.
After a contest, I can gain 40 pounds in about three weeks, and 15 pounds overnight.