Muscle Dysmorphia or Bigorexia is a mental disorder whose focus of concern is the underestimation of body size and shape as a result of the distortion in body image experienced by those affected. This is a new mental disorder and, therefore, is not yet classified in the manuals for mental disorders. While some authors propose its classification under an Eating Disorder (ED), others argue that it is a Body Dysmorphic Disorder (BDD), or have even been able to justify its classification as an Obsessive-Compulsive Disorder (OCD). Due to the disparity of opinions, this study aims to contribute to classifying Muscle Dysmorphia, as a mental disorder, by the decision tree classification technique of data mining. The items that take on increasing importance within this classification method are the ones related to body size and shape that participants have, perceive and desire. The results inform us that the most important variables are related to a BDD. This is the reason why we contribute to classifying Muscle Dysmorphia through the diagnostic criteria of BDD
