In Eva Musbys book there is an entire chapter offering principles to enable parents to help their child to eat, based on a bungee-jumping analogy. Because it’s likely that with anorexia and some other eating disorders, people experience a lot of fear when they are asked to eat and similar principles apply to preventing over-exercising, purging and so on.
This is a favourite of quite a few parents so she created this 5 minute video covering two of the principles which are about the use of logic and about being someone who inspires trust.