I have found that if you stay away from sugar, you will not gain your weight back. Sugar is the enemy. The best thing is not to keep any soda, candy, cookies, ice cream, etc. in the house, and we've been doing well! (We're going to cheat tomorrow at the Memorial Day Picnic.)
Let me know if you were able to get back on the diet after cheating. Unfortunately for me, once I get sugar in me, it's over.