I haven't studied it, really. Maybe nobody has; schizoid personality isn't a huge focus of research. I put "schizoid" and "anorexia" into a Medline search and got only fifteen results, many of which weren't very relevant and one of which said that there wasn't much connection between anorexia and personality disorders. "Schizoid" and "appetite" had only one result, which wasn't relevant at all... Sooo... yeah, you may be asking a question nobody's answered yet.