I lost 5 pounds before the cruise, and gained 3 back on the cruise. I normally exercise quite a bit (Tae Kwon Do, which is the tkd in my screen name), and only got in one mile walk and one 30 minute treadmill as official exercise during the week long cruise. But, we did walk quite a bit in Grand Cayman.
The way I dealt with all the eating was 1) only eat it if I really wanted it (i.e. just because the pizza, hot dogs, etc are at the pool, not to mention the COOKIES, don't go get it if you're not hungry!) 2) didn't drink hardly any liquor (one drink on the free Capt's gala, one drink out of our stock for the week), 3) ate half of what was brought out at the meal, and 4) concentrated on the veggie dishes at the buffets.
The last suggestion was probably the best one! I wanted to try some of everything, and it was really good! But since I NEVER eat an appetizer, main course, and dessert at home, if I had cleaned my plate, I probably would have gained 10 pounds! Instead, I just ate half of everything. The only exception was the carmelized cheesecake!!!!! It was the BEST!