Obviously "have you lost weight?" is out of bounds.
So, it's more than very impolite, it's socially wrong, to lie or be reticent in the least about disclosing your age.
The only person I have ever met that thus far that has been reluctant to answer the question of "what do you do?" is my father, and I'm not sure why.
I'm going to be a crazy mountain lady with nine cats all named 'cat' and seven lizards named after ex-husbands and my children will hate me but my grandchildren will love me and I will ride around on horseback with a shotgun scaring unwary campers with my hair up in a hat like Katharine Hepburn in 'The African Queen' and when my kids send social welfare workers to put me away I will chase them off my property with my shotgun.