Well much longer than it would if you stick to TFR. You've only done a week - you may well feel better about eveything when you have your first weigh in - that's what got us all from week to week! If you REALLY can't hack it then think again but I'm sure of you stick it out for 2 more weeks you'll get to the stage where you wonder why you were worried. ... Most of us ended up not even wanting to go back to 'real' food in the end!! Real food is soooo much harder to manage!
Good luck whatever you decide x