if it is ARFID.. my 'guidelines' as a mum who has a now 19yo with it.
don't make meal times stressful, cook what they will eat, do not comment on it.
make other foods available on the table, if they ask to try, let them, do not comment on it.
ask if they want to try stuff, if they say no, check they're sure, leave it at that.
involve them in shopping, ask that they stay around while you cook, talk about food with them.
Encourage them to smell/touch things without tasting, with no pressure.
never, ever, EVER punish or tell them off for not eating things.
never, ever, EVER make a huge thing of them eating anything new, however much you want to.
The first rule of food in ARFID club, is we do not comment on Food in ARFID club.
Basically, as long as they're eating, the nutritional value is secondary, its just important they eat. Feed them what they eat. If they're eating, their body will get what it can from it, if they're not eating, you have problems.. so feed them what they will eat.
My son hasn't willingly eaten a vegetable or a fruit in his whole life.. we get some in via fruited bread which he will eat, and we get some in via spaghetti sauce. He has to take a daily multivitamin.