My Dad didn't say anything about my early weight loss, but I think my aunt ratted us out, because he confidentially told me he "didn't believe in Atkins." So I sent him some articles from the Internet, most notably "What if it's all been a big fat lie?" and he did a 180!
Just quizzed me about how many vegetables I've been eating, and said that was good.
I spent a week with my inlaws who kept asking me "What kind of restaurant can we take you to?" I kept saying "Any of them."
By the end of the visit we were discussing it quite often.
So I've been fortunate. Initial resistance has turned into support. And I look good and feel good. That's what's important to them.