BeeDott, have you ever thought about complaining to the manager? They would probably like to know that their wait staff are driving away customers by disparaging personal habits that are none of their business.

I must be lucky because the people in the restaurants I go to have all been really accomodating about my substitution requests. In places where they know me, they often ask me for weight loss advice. I think I've even talked the owner of one place into adding a low carb entree! But if I were in a restaurant and the waitress were truly rude about my order, I'd complain.