Abstract
OBJECTIVE: This review systematically examines the role of loneliness in clinical and subclinical Eating Disorders (ED), assessing its impact on symptom severity and exploring underlying mechanisms across different populations. METHOD: Following PRISMA guidelines and registered with PROSPERO (CRD42024565108), a comprehensive search was conducted in PubMed, Scopus, PsycINFO, and Web of Science. Inclusion criteria required quantitative measures of loneliness and ED symptoms in clinically diagnosed or subclinical populations. Pandemic-related loneliness studies were excluded. Bias was assessed with the Downs and Black checklist. RESULTS: A total of 15 studies with 2907 participants met the inclusion criteria. Findings revealed loneliness as a transdiagnostic factor in ED pathology. In clinical ED populations, loneliness was associated with increased symptom severity, particularly for Bulimia Nervosa (BN) and Binge Eating Disorder (BED), where emotional dysregulation was mediated by loneliness. Findings from subclinical samples suggest that loneliness may be an early psychosocial correlate of ED symptoms, particularly among young adults. CONCLUSION: Loneliness significantly contributes to ED development and persistence across clinical and subclinical populations, with potential implications for treatment. Social support and emotional regulation interventions may mitigate loneliness and improve ED outcomes. Future research should address gender differences and incorporate diverse populations to deepen understanding of this relationship. TRIAL REGISTRATION: PROSPERO Register: CRD42024565108.