Anagnostopoulou, Bailie & Troop, 2026

Objective
Eating disorders are severe mental health conditions with high morbidity and mortality. Despite existing evidence-based treatments (e.g., cognitive behavioural therapy), relapse rates remain high. Consequently, third-wave therapies such as Acceptance and Commitment Therapy (ACT) have gained interest as promising alternatives. However, comparative evidence of ACT's effectiveness against established treatments remains limited.
Method
This systematic review and meta-analysis of randomized controlled trials (RCTs) evaluated the effectiveness of ACT in reducing eating pathology among individuals diagnosed with eating disorders and those at elevated risk. Control conditions included active treatments, treatment as usual (TAU), and waiting list. The analysis also examined moderators including age, treatment duration, and population type (clinical vs. at-risk) on eating pathology.
Results
Adhering to PRISMA guidelines, searches in PsycINFO, CINAHL, and PubMed Central identified nine eligible studies (total number of participants = 455). ACT interventions demonstrated a significant moderate effect size in reducing eating pathology (Cohen's d = −0.60, SE = .19, Z = −3.06, p = .002 [95% CI = −.98 to −.21]) across both diagnosed and at-risk groups, compared to control conditions. The effect of ACT was stronger in studies with more sessions, but no other moderators significantly influenced outcomes.
Conclusion
This review reinforces ACT as a promising approach for treating EDs but also highlights the need for further high-quality RCTs. Clinically, it supports incorporating ACT into standard care, with a focus on enhancing psychological flexibility and adapting interventions for diverse populations. Future research should also explore ACT's potential in prevention and relapse reduction.