Use positive reinforcement when there is actually obvious visible progress.  The main point here is to not compliment a fat just for showing up to the gym for ten minutes.    I still disagree with you, though.  Positive reinforcement might make them think that maybe their goals are too strict and that since they've been doing so well (since people are noticing!) they deserve a reward cheat day (which turns into a week, etc).    edit:  and for the record, I don't understand the concept of "cheat days" at all.  You've been on "cheat days" every single day of your entire life leading up to the point where you decided to lose weight.  You don't deserve a "cheat day" at all.  EVER.  Being thin/fit is a lifestyle.  My BMI is 20, and I'm about to eat a piece of chocolate cake, and I still won't go over 2000 calories for today.