Cheat days actually rev up your metabolism if you eat right for a week. If you're eating healthy and pure, then you throw in a sort of sweet, your body says "WTH is this?!" and burns it super quick, and keeps that up for a while to make sure none of it is left in the system. I've talked to several personal trainers, and they all recommend to have 1 cheat day a week. Don't cheat all day, just give yourself a treat. Does a body good
IMO, I wouldn't do it in the beginning. I'd start the cheat days after about a month of eating right. If you really want to figure it out, personal trainers will have alot more information.