Predictors of psychopathology response in atypical anorexia nervosa following inpatient treatment: A propensity score matching study of weight suppression and weight loss speed

Introduction: This study examines weight suppression (WS) and weight loss speed (WLS) in atypical anorexia nervosa (AN) and its implications for treatment outcomes, compared to people with AN and bulimia nervosa (BN). Method: A mixed cross-sectional and prospective design was employed, assessing WS and WLS in people with atypical AN, AN, and BN. Participants were matched for age, gender, age of onset, and disorder duration. Clinical measurements and eating disorders questionnaire (EDE-Q) scores were employed to evaluate the response to treatment. Results: Individuals with atypical individuals exhibited WS patterns similar to AN, distinct from BN. Rapid WLS predicted clinical responses in atypical AN and BN, underscoring its treatment relevance. Atypical AN showed higher eating psychopathology scores than AN or BN, emphasizing the need for a reframed diagnosis. Discussion: Understanding atypical AN's connection to restrictive behaviors and weight loss informs screening, assessment, and treatment practices. Recognition of atypical AN's severity and adoption of tailored approaches are essential for recovery. This study highlights the significance of WS and WLS in atypical AN treatment outcomes, offering insights into clinical practice and care. The proposal to reframe atypical AN as a restrictive eating disorder emphasizes its clinical relevance. Public significance statement: The phenomenon of weight suppression, involving the discrepancy between past highest weight and current weight, has garnered attention due to cultural pressures emphasizing fitness and appearance. This study focuses on its implications in atypical anorexia nervosa, aiming to uncover the relationship between WS, its speed, and treatment outcomes. The investigation contributes insights into tailored interventions for atypical anorexia nervosa and enriches the understanding of this complex disorder's dynamics.