This is a MYTH!
While I don’t recommend fasting regularly, fasting for holidays is perfectly fine, and it’s good to break the routine from time to time. There’s no reason for it to mess with your diet. It’s all in your head because your body convinces you that you’ve been deprived of food and are “STARVING,” and your mind wants you to make up for it.
You can’t replenish unused calories during a fast, so eating a lot and heavily after a fast, is in fact counterproductive.
Rule #1: Get right back on the wagon as if you HAD been eating the whole time. Just remember to keep it light right after the fast, so you don’t get stomach aches and discomfort.