Study protocol of the eating and nutritional habits in athletes and controls longitudinal examination – ENHANCE Study

BACKGROUND: Training and body composition requirements in elite sports may elevate eating disorder (ED) risk. Current estimates suggest a range of 1-28% prevalence of ED in elite athletes, reflecting methodological heterogeneity, underreporting, and limited research focus. EDs adversely affect physical health (e.g., osteoporosis, fatigue, injury), psychological well-being, and athletic performance, often persisting beyond athletic careers. Sport-specific demands may obscure ED symptoms, making underdiagnoses likely. This longitudinal study's objective is to furnish proof for the theoretical model of disordered eating in elite athletes by examining the role of sport-specific indicators, to improve early identification and psychological diagnostics. METHODS: Three-hundred elite athletes from weight-sensitive (ballet, bodybuilding) and less weight-sensitive (soccer, racket sports, basketball) sports will complete assessments at four time points. A subgroup of 90 athletes will participate in clinical interviews. Logistic and hierarchical regressions will identify ED risk indicators and estimate the prevalence of EDs in athletes. Receiver Operating Characteristic (ROC) analyses will assess diagnostic accuracy of single and combined indicators with reporting of sensitivity, specificity, and the Area Under the Curve (AUC). Group differences and measurement invariance of ED instruments will be tested between the athlete group and 300 non-athlete controls. DISCUSSION: Identifying reliable ED indicators in elite sports may support early intervention. This theory-based approach aims to enhance diagnostic accuracy and athletes' care. TRIAL REGISTRATION: Prospective registration of the study in the German Clinical Trials Register (DRKS00035100) on 03 February 2025.