i honestly think that for some people, the idea of cooking is terrifying
if you have never seen your parents or family cook and have no idea how to make a balanced meal and have never done it, the thought of starting is scary
it sounds complicated, expensive and time consuming
perhaps you could give her some really simple recipes and /or cooking lessons?
maybe invite her round for dinner but ask her to help you cook?
the first time i cooked a roast dinner as a newly wed, it took me hours and i had to phone my mum for help! after a b it of practice i find it one of the easiest things to make!
she needs some help and encouragement, rather than condemnation
she sounds possible depressed and over anxious and if she is on her own, maybe the cooking is a step too far, and she simply could not cope
not right, but i believe this is more of a desperation and depression/anxiety issue than neglect/abuse esp. WRT to their weight issues as babies