People like that are fucking infuriating. There have been some great suggestions so far. My two pennorth:
Have you put on weight? I really couldn't say, I never weigh myself. People who obsess about weight are sooo boring, aren't they?
Are you really having a potato with that?' Of course I am. It's a potato, not crack. Nothing to be alarmed about. Don't tell me you're worried about eating a potato? Are you suffering a bit with anxiety at the moment?
'Isn't (DGD) walking yet?' No, it would be very early, and in any case, DS/DD and spouse are really not the sort of tedious, neurotic parents who push their child on these things. She'll walk at the right time for her.
You don't see much of your son do you? Not so much lately, he's been super busy at work. We are so proud, did I tell you that.... (go off on 20 minute boast about son's promotion, important project, how well boss thinks of him, yadda yadda).
'Why haven't you been promoted yet? Well, my boss keeps asking me why I don't apply for them, but I'm so happy doing what I do and don't want the extra stress. I'm just so blessed to love my work! How about you?
She needs to be served with her own sauce.