How much weight do you think I will lose?

Are you trying to lose weight? There are too many variables to be able to answer your question accurately. If you will be expending more calories than you normally do, and you listen to your bodies signals, you may not lose too much, as generally you will compensate by consuming more calories. However, if you want to lose weight and are using this opportunity to do so, the safest way is to obviously eat sensibly and drink lots of water. 2 lbs a week is a 'proper' amount of weight to lose, and obviously, the slower you shed, the easier it is to keep off. Have fun on your trip!