Two days in, wife and i felt TERRIBLE and realized it stemmed from breakfast. At home I eat a nutrigrain bar for breakfast - on board I was eating eggs Benedict, potatoes, bacon, bagel, fruit, and a donut ... oh, and those mexican breakfast burrito things... oh, and corned beef hash... why? b/c it was there. My dog has more constraint than I did
So we stopped eating big breakfast - bagel and fruit for the remaining days.
I'm not sure it's possible to overeat in the MDRs unless you order more than one entree.
Lunch can be tricky too but not hard if you stay away from Cabanas.
Here's another good tip - just take the stairs. It burns calories and you wont be furstrated by the elevators !