P-51 Bidirectional risks of obesity and mental health disorders: a systematic review and meta-analysis

Methods: A systematic review and meta-analysis were conducted using PubMed, PsycINFO, and Scopus for studies published between 2020 and 2025. The search yielded 12,255 records from PubMed, 13,613 records from PsycINFO, and 11,500 records from Scopus, totaling 37,368 records identified before deduplication. Eligible studies included longitudinal cohort, case-control, and cross-sectional designs with clear temporal or bidirectional analysis. Populations comprised adults and adolescents (≥12 years), both sexes, from general or clinical settings. Studies were excluded if they focused solely on children under 12 years, pregnant women, or populations with primary organic brain disease; lacked standardized definitions of obesity or validated psychiatric measures; or examined obesity/mental health outcomes secondary to another primary condition. Final studies included in the meta-analysis reported odds ratios for depression, anxiety, neuroticism, psychosis, and personality disorders in relation to adiposity markers (BMI and waist circumference).

Results: High-volume data confirmed significant bidirectional risks: obesity was associated with increased neuroticism and lower life satisfaction, while psychological distress predicted subsequent weight gain. In young adults (20–39 years), approximately 45.3% of those with depression also presented with obesity, significantly higher than the 30% prevalence in non-depressed peers. Obesity was identified as a “pleiotropic risk state,” frequently preceding a wide spectrum of psychiatric diagnoses, including psychosis and personality disorders, particularly in females. Psychosocial analysis indicated that weight stigma and internalised shame significantly mediated the transition from overweight status to psychological distress, while social support acted as a protective buffer.

Conclusion: A robust bidirectional “vicious cycle” exists where metabolic dysfunction and mental ill-health reinforce one another through systemic inflammation and weight stigma. Clinical interventions must shift toward integrated, holistic models that address metabolic health and psychological well-being simultaneously to break the cycle of comorbidity.