that you have a sensitivity to flour and sugar and can't eat some of the food. At the family get-together---you could pretend to feel sick to your stomach. You could even bring an Atkins bar and eat it in the bathroom to get over the hungries.

Regarding social situations:

I always offer to bring stuff. Sometimes I don't even offer, I just bring it. You could bring a great salad and a cheese and vegetable plate. You could bring some fruit(if you're eating fruit). If you bring stuff you can eat, you can fill your plate up with that stuff and take a piece of pizza too. You can either eat the pizza(one piece) or somehow get it into the garbage without other folks knowing.