Like Ken, I avoid debates or even serious responses to the now rare question of whether I've lost weight. My weight loss was 4 years ago, and people have now started getting used to me as is. As for the discussions with sincere people, I give them the "elevator speech" which is a very brief overview of what I find helpful, and point them to the two primary sites I find most useful if they're interested in further investigation. This site is one and DietDoctor.com is the other.