Scrutiny
It's seriously rude to make comments about what anybody is eating, regardless if they are family or not. But family does seem to feel like they can take liberties that others would never imagine
I like Gwen's suggestion of changing the subject, which should give them the message that what you eat, how you eat and how much you eat are NEVER a topic of conversation. I bet when you were heavy they didn't verbalize their concerns every time you took a bite, right? Just because you've lost weight doesn't make it OK now.