I got back from South America recently, and I actually lost about 2kgs while I was over there for 2 weeks. (Let's not talk about the fact that I put it back on though after bingeing on junk food while marking end of term reports...
I didn't really set out to lose weight while I was over there, and I ate out almost every night because the food was so amazing and cheap! I think that can be attributed to a couple of reasons:
a) I was so excited about seeing a lot of new places that I thought about food less, and therefore didn't snack during the day.
b) We did a lot of walking around while exploring cities, ruins etc and also a lot of climbing up stairs.
c) A lot of what we did was based on organised tours, so we tended to really only eat three main meals a day.
I think the walking/climbing was the key - I could eat what I wanted to, and I just burned off the calories in the day. While we were there, I was interested in trying a lot of local/traditional foods, and they tended to be really healthy. Bonus!
My advice to you is just to go and have an awesome time, and enjoy everything in moderation
. Make healthy choices if they're available, but don't beat yourself up if you slip up a bit while away. Try and stay active, go for lots of walks and explore new places. You're going to Fiji, so you're probably going to do a lot of swimming/water activities, and these are a great way to burn calories.
Good luck and have a blast! I'm off to Japan just after Christmas, but fortunately most of the food there is pretty healthy. We'll see how I go this time