Anorexia tends to emerge in susceptible individuals during puberty, driven by sex steroid hormone changes.

“The body changes, the brain changes, perceptions, change, one's own self perception, changes. And most of those changes are driven by changes in circuitry within the hypothalamus. So, neurons that are controlling the production of the so-called sex steroid hormones, things like testosterone, estrogen, and related hormones, prolactin, et cetera. Those are all changing at very rapid rates. Anorexia tends to show up around this time in a subset of individuals who on the face of it seem to find food, aversive.”