Bigorexia

There exists a clinical condition that is the opposite of anorexia called Bigorexia. The person affected by it becomes obsessed with the idea that their body is too small, too skinny, insufficiently muscular, or insufficiently lean, although in most cases, the individual's build is normal or even exceptionally large and muscular already. It affects mostly males, particularly those involved in sports where body size or weight are competitive factors.