This Q and A from Miss Manners I found on the Tribune site is great! I love Miss Manners... plus you all know how I love to discuss any sort of food related social protocol.
Dear Miss Manners: Dieting in public is a serious etiquette problem in a society that has made saints of women who wear a size 2. It is rude and offensive for a person to attend a joyous food-related outing and spoil the trip by ordering "a small salad."
Public dieting casts a pall of misery over any such occasion. The argument that the outing is about the fellowship is only partially true—the fellowship is enjoying a good meal together. The occasion is about the food.
Holiday dinners and meals out with friends are a time, if not to eat heartily, to at least eat well—even if one chooses grilled instead of fried chicken or replaces the dressing with vegetables at Thanksgiving.
If one must diet in public, it should be done with absolute discretion and must involve a variety of tasty foods chosen from what has been provided. If the dieter wants a diet soda, she should ask for it quietly, as though requesting something with which to take medication and have it poured into a glass to ensure that the nature of the drink is not obvious.
If a person is on a super-restricted diet that requires she eat abnormally, she needs to stay home, instead of making everyone miserable.
Perhaps she can join the group later for a concert or movie if she is not too weak to stay out past 8 p.m.
Gentle Reader: Miss Manners suggests that you try harder not to notice what other people are eating. A lot harder.
Monitoring what other people eat is a good way to ruin a holiday or gathering of friends, whether it is dieters voicing disapproval of hearty eaters or the more rare reaction that you have.
After you stated your desire to ostracize everyone with medical food restrictions, Miss Manners banned you from any discussion about what constitutes fellowship.