Hi - it's another 'how long's a piece of string?' type question.
If you stick to it and eat fairly healthy portions and have a couple of slips with your triggers towards the end it's designed to leave you at the same weight at the end as you started it. However, if you stick to it rigidly and follow the LL portion sizes you will probably lose weight. If you don't follow it you'll put on weight, and quite quickly! (I've put on 18lbs)