Well for starters, if this is about you I hope you know that you are worthy of food my love. It's not much coming from a stranger but you are.
If it is weight-based, it would probably be described as atypical anorexia unless the person is severely underweight.
If it is based on control it could be described as Avoidant/Restrictive Food Intake Disorder.
I hope this helps and again, if this is about you my love, please get help. I have been dealing with mine alone and it ruins so much stuff.