Anorexia nervosa as an anxiety management tool
If I'm understanding your question, you're wondering if anorexia nervosa is a symptom of other underlying problems in a person's life.

This is a current theory being supported by "Mental disorders as complex networks: An introduction and overview of a network approach to psychopathology" written by Nuijten et. al. The paper describes how instead of seeing a disorder as a single "latent variable" connecting all the symptoms, all the symptoms should just be considered as a network reinforcing themselves. This is demonstrated in the figure below taken from the paper:



For a discussion of the paper, see "Mental Disorders As Networks" by SlateStarCodex.