The aim of the present study was to predict unhealthy eating behaviors based on object relations and attachment styles, with the mediating role of defense mechanisms. This study is a descriptive-correlational research. The statistical population consisted of students from the University of Science and Research in Tehran during the 2023-2024 academic year. Data were collected using the Dutch Eating Behavior Questionnaire (DEBQ), Object Relations Inventory, Adult Attachment Styles, and Defense Mechanisms Inventory (DSQ-40) and were analyzed using structural equation modeling. The results showed that object relations had a significant positive impact on unhealthy eating behaviors. Developed defense mechanisms directly influenced unhealthy eating behaviors. Secure attachment had a significant effect on eating behaviors through developed defense mechanisms, while insecure attachment styles did not show a significant impact. The model fit indices indicated that the theoretical model of the study had good fit, demonstrating that object relations, attachment styles, and defense mechanisms influence unhealthy eating behaviors, and strengthening positive factors could help prevent and reduce the prevalence of these behaviors.
