It's not really neccessary to wear the diet on your sleeve, so to speak. I NEVER go around telling people what I can or can't have because I'm on the Atkins. and I've had all sorts of wierd eating habits. I just say, well, I'm not a big fan of bread, or rice, or pasta for many reasons...one, that's what everyone eats in college when they are poor so it's easy to get sick of!! 2. It just doesn't fill me up or taste nearly as good as meat does.. also, I'd rather eat all my meat than eat a freakin' potato. Also you can say that you jstu avoid processed food, because essentially that's what Atkins does.
I've always focused more on what I CAN eat rather than what I CAN'T eat. It's really not necessary to make a big deal about how you eat.