Going away but I don't want to gain weight?

So I'm going to Israel for 2 weeks and I won't have access to a gym (or the time). I'll be walking and hiking and kayaking and stuff, but my friend said she gaind 2 pounds (most likely from the lack of sleep..we only get between 4-6 hours, maybe 7 if we are lucky). I don't want to limit my food intake, since I want to try all the good food, and plus I need the food (and water) since it'll be like 90/100 degrees. What should I do so I don't gain too much weight, since I lost a few pounds (after a LOT of hard work). Thanks!