Your mum sounds like mine, Nessie, although I have to give my mum massive credit for finally getting to grips with the fact that her little round mother and her little round aunties all got diabetes and an early trip to the cemetery, and her little round cousins are all getting diabetes and heart disease, and doing something about her little round self instead of pretending that the cakes in the house are for the grandchildren, who visit about 4 times a year and aren't very interested in cakes.
I didn't ask my patient what she ate apart from the celery, or I'd have got the stock answer of "One half of one chapatti and two little teaspoonfuls of dhal, nothing else, no chevda, no gulab jamans", and then I'd have had to decide whether to smile sweetly or read the Riot Act. And since she's really a rather nice lady, I took the conflict-avoidant route for once.