Muscle dysmorphia is a disorder that is recognizable by the preoccupation of one's own physical build and muscle development, and includes attitudes and behaviors that underlie the extreme desire to increase muscle mass and maintain low levels of body fat. Although it is known that the pressure on men to achieve an almost unattainable ideal physical appearance, mediated by the increasing use of social networks, is increasing, it is believed that the prevalence of musle dysmorphia is still extremely underestimated. The primary objective of this study was to examine the impact of exercise history and exercise experience on muscle dysmorphia symptoms and the mediating impact of the need for physical comparison with others on the relationship between time spent watching or listening to content related to fitness online and the presence of muscle dysmorphia symptoms. The study involved 397 men aged 18 to 35 years. Special questions were constructed to measure online time and exercise history, while the Muscle Dysmorphic Disorder Inventory (MDDI) was used to check for symptoms of muscle dysmorpia, and the revised version of Physical Appearance Comparison Scale was used to measure need for physical comparison with others (PACS - R ). The results showed that those who are currently engaged in exercise for the purpose of increasing muscle mass and strength or weight loss have significantly more pronounced symptoms of muscle dysmorphia than those who no longer engage in such activities or have never engaged in them. Mediation analysis showed a partial mediating effect of need for physical comparison with others on the relationship between the time spent watching and listening to fitness content online and the severity of muscle dysmorphia symptoms. The implication of these results is that active exercisers show significant expression of muscle dysmorphia symptoms and that there is a link between social media use and body image problems, to the point of dysmorphia development, and this link is influenced by some stable traits, such as the need to compare one's physical appearance with the physical appearance of others.