Hi Frey, never posted on your therad but was just reading through... yeah, visiting the parents can be TOUGH!
One of the things that I did was set the tone up early. Even on the first day, my mom wanted to feed me bread-pudding and parmesean (fried) chicken. I told her thanks, but only had a bite of each and then loaded up on veggies.. I also hammed it up, and told her how utterly sad I was, I could not eat the food right now she makes that I love SOO much. She really understood, and the next day cooked a totally healthy (and unbelievably) awesome meal!
Gym is a sweet idea as well. I definitly did that 8 of 10 days I was home. It also helps counteract the calories that are unavoidable (mom's cookies, or whatever it may be).
Lastly, I set my expectations to maintain my weight, not just to lose. I changed my long-term goal to accomodate the 10 days I was home, and said... I will lose 50 poounds over 4 months instead of 3.5 since i knew I was going to wash this week+ with my parents.
Best of luck!