- Muscle dysmorphia (bigorexia) What is muscle dysmorphia Sometimes called bigorexia, muscle dysmorphia is the opposite of anorexia nervosa. People with this disorder obsess about being small and undeveloped. They worry that they are too little and too frail. Even if they have good muscle mass, they believe their muscles are inadequate. In efforts to fix their perceived smallness, people with ...www.anred.com/musdys.html