Jedi: With some people, you could write a book on the awkwardness of social situations. Food and culture are almost inextricably intertwined, and when some people will start to raise their eyebrows at a mere leaning in a primal or low-carb direction, you can imagine the reaction to very low or zero carbers. But like I said in another post, and like Lemmy from Motorhead once said: Some people are just dying to be offended about something!
I find the less of a fuss I make about whatever I eat or don't eat, the less of a reaction I get from others in general. But I've always loved to cook and still do, and I understand the negative feeling, however small or understandable, when someone declines something you tried to make the very best you could...and so if necessary, the optimal thing to do IMO is to tactfully yet explicitly make it clear that your choices are in no way a rejection of their hospitality, friendship, love, or whatever they're trying to offer besides the mere physical food itself.
Give me a friendly Christian any day over an asshole atheist.