How do I respond to weight compliments and weight questions smoothly?

You could tell them how you did it and not be so coy; they need help too and you should give it. As to judging, it is not judging to tell them how you did it, I don't know why you're even asking this, you're in a position to help others who are where you used to be and I find it troubling you're so reluctant to help them. Sounds like you're afraid of competition and enjoy being in the cat bird seat.