There is mixed evidence for the relationship between increased levels of the drive for muscularity (DFM) and disordered eating behavior in males, therefore this study analysed the relationship between DFM and disordered eating behavior, giving particular relevance to the patterns of cognitive appraisal. A convenience sample was recruited from fitness centres and sport clubs with 308 participants, all males. Losing muscular mass represented a negative experience for participants, promoting a higher perception of threat appraisal. In addition, losing muscular mass was related to more muscularity-oriented behaviors and disordered eating behavior. Cognitive appraisal mediates the relation between DFM and disordered eating behavior. The results highlight the role of cognitive appraisal in DFM and disordered eating behavior in males in sport contexts.