Duration of Untreated Eating Disorders and Its Impact on Outcomes: An Updated Systematic Review

The duration of untreated eating disorder (DUED), defined as the time between the onset of clinically significant symptoms and the initiation of appropriate treatment, may influence prognosis and treatment outcomes in eating disorders (EDs).To update the evidence on DUED and its association with clinical outcomes in individuals with EDs. A systematic review was conducted according to PRISMA guidelines, with protocol registration in PROSPERO. PubMed/MEDLINE, Embase, and PsycINFO were searched for studies published between January 1, 2020, and July 20, 2025. Eligible studies included original research assessing DUED in individuals diagnosed with EDs. Two independent reviewers performed study selection and data extraction. Findings were synthesized descriptively and compared narratively across studies. Of 753 records identified, 11 studies met inclusion criteria (7 interventional and 4 non-interventional). Combined with 14 studies from the previous review, 25 studies involving 21,270 patients were analyzed. Most participants were female and diagnosed with anorexia nervosa (AN) or bulimia nervosa (BN). Significant heterogeneity was found in the definition and measurement of DUED. Longer DUED was associated with greater illness severity, lower motivation, poorer treatment response, and worse long-term outcomes, particularly in AN. Early intervention models such as First Episode Rapid Early Intervention for Eating Disorders (FREED) were associated with shorter DUED, reduced waiting times, and improved eating disorder psychopathology. Longer DUED is linked to poorer outcomes, especially in AN. Early intervention strategies such as FREED may improve prognosis, although delayed access to treatment remains a major barrier.