Just laugh off and be polite and in general ignore and if they get really annoying just dont talk to them about the weight loss and how well you are doing. There is a thread somewhere around here which looked at these issues. Your doing this for you not for them, if they cant be bothered to change there lifestyles then they shouldnt be getting jelou
Just ignore those comments and focus on yourself. Also, just imagine how fun it would be to make them even more jealous once the result of your weight loss efforts start showing.