Hi Ruth, I wouldn't call the hostess beforehand either. There will probably be lots of food you can eat, so you just put the good things on your plate that you know you can eat. I think using common sense will get you through the dinner without guilt. It'll be easier than you think especially if it's a buffet. If it's a sit-down dinner, take a piece of meat (chicken or fish) and lots of vegetables, holding off on the potatoes. And a glass of white wine to be sipped throughout the meal. If there's a choice of dessert, go for the least damage like 1/2 slice of something and leave some on the plate, or simply decline if you can. I attended a birthday luncheon buffet and did just that, even part of the piece of cake that was given to me (didn't eat the icing) and my numbers later on in the afternoon were only slightly higher than normal for me. I had a salad for dinner and everything was fine. Don't stress out about this! Tell us how it was! We want to know!