I used to have 1 cheat meal a week, and always cheat (to excess) on holidays. I no longer have weekly cheat meals because they were delaying my weight loss, but as I just started lifting, I may resume them if it doesn't impact my weight loss.
Also I have read a bunch of recent research that one meal that kicks you out of ketosis can force you to re-adapt to a ketogenic state, requiring 2-4 weeks. More research needs to be done, but initial surveys by Phinney and Volek point at that.
Former 440 lbs in transformation.