Q. An anorexic person died from complications related to the on-going overall decline in her bodily health. Is that termed a suicide?

A. Anorexia Nervosa is a serious, potentially life threatening mental illness and eating disorder. It is characterized by an abnormally low body weight, intense fear of gaining weight and a distorted perception of body weight disease: it enjoys the highest fatality rate of any psychiatric disorder. (National Eating Disorders Collaboration, et. al.).
As mentioned in the last question, Halacha (Shulchan Aruch Y.D. 345: 2) considers the one who committed suicide to be a meaved atzmo lodaas, only if he committed suicide when in a psychologically stable state of mind.
When there are any doubts, the assumption of the Poskim is that a suicide was not psychologically stable, and it is treated as one who died by natural causes.
Horav Shlomo Miller’s Shlit’a opinion is that a medical professional familiar with the case as well as a competent Rabbi should be consulted.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a