The aim of this thesis is to examine the role of excessive social media use in the development of eating disorder symptoms. The thesis is part of the project "Testing the 5C model of positive youth development: traditional and digital measurement (P.R.O.T.E.C.T.)," led by the Faculty of Education and Rehabilitation Sciences, which, in cooperation with partner institutions from across the Republic of Croatia, conducts a large-scale study on the positive development of youth, tracking an entire generation of high school students. To examine the influence of excessive social media use on the occurrence of eating disorder symptoms, this thesis utilized the Problematic Social Media Use Scale (adapted from Jovičić Burić et al., 2021) and the SCOFF questionnaire (Morgan et al., 1999). For the purposes of this thesis, a sample of 300 high school students from Varaždin County was selected, consisting of 151 males, 141 females, and 8 respondents who chose not to disclose their gender. The results showed that the majority of respondents, 46.0%, rarely excessively use social media, while 16.5% of respondents are at risk of eating disorders. Examining gender differences in the number of eating disorder symptoms revealed a statistically significant correlation between gender and the risk of developing eating disorder symptoms. Most male respondents exhibited no symptoms of eating disorders, whereas female respondents more frequently exhibited two or three symptoms. Furthermore, it was found that higher scores on excessive social media use significantly correlated with a greater number of eating disorder symptoms. Based on the results of this thesis, the importance of understanding the impact of social media on the overall physical and mental health of adolescents is emphasized, and it opens the door for further research in this area, which is highly necessary due to the increasing prevalence of these phenomena.