With body dysmorphic disorder,the focus tends to be on a particular body feature,whereas with muscle dysmorphia,the focus is generally on an obsession with lack of muscularity.

Body Dysmorphic Disorder (BDD) often involves preoccupation with one or more perceived defects or flaws in physical appearance, which may not be observable or appear slight to others. Muscle Dysmorphia, a subtype of BDD, specifically involves a preoccupation with the belief that one's body is too small or insufficiently muscular, despite possibly having a normal or even muscular physique.