I had lost 18 pounds between my USA visit in October and my USA visit now i May, and I didn't want to gain all those pounds again. But I also didn't want to say NO to all tha "wonderful" American food (no, it's not wonderful food, I just like it a lot, bwahaha!!)
So, I tried to limit myself to only 3 Krispy Kremes a day during work-part of the trip (as opposed of sometimes a dozen of those donuts I ate when I was in Texas a couple of years ago...

) and I also tried to limit myself at WDW.
I didn't eat everything I wanted to try, but tried more than I had planned. It is vacation, so I can splurge a little bit!!
In the end, I only gained 2 pounds, and I blame that on the one Sprite (as opposed to the diet coke) and the alcohol I had!! (and the ice cream, krispy kremes, funnel cake, sundaes, ...

)
I try to avoid appetizers/ desserts and sodas that are not diet. I am not going to count calories on vacation (as if I do that at home! ha!) but I still try to be reasonable...