Modeling of mediator and moderator effects in Structural Equation Models

Structural Equation Modeling (SEM) is a powerful analytical method frequently used in social sciences, yet it is relatively less preferred in the health scinces due to its large sample size requirements and the more challenging assessment of model fit compared to regression analyses. However, the flexibility and depth offered by SEM allow for a holistic examination of the biological, cognitive, and social contextual variables that affect individual health. In doing so, it can provide valuable insights into the areas that should be prioritized to ensure a healthy life. In particular, SEM's contributions are valuable in addressing issues such as obesity and related unhealthy eating behaviors. Therefore, this study aims to present an application example of two fundamental SEM models (mediation and moderation) and compare them with similar models conducted through linear regression. To this end, the study examines the mediating role of psychological stress in the relationship between emotional regulation difficulties and binge eating, which is associated with obesity, and the moderating role of Body Mass Index (BMI) in the relationship between emotional regulation difficulties and binge eating. The model tests were conducted with a sample of 444 individuals, aged between 17 and 62, consisting of 303 women (68%) and 141 men (32%). The findings suggest that psychological stress plays a mediating role, while the moderating role of BMI was not found.