Dietary Inflammatory Index and Its Relationship With Anthropometric Indices and Mental Health Outcomes in Adolescent Girls: A Cross‐Sectional Study

Aim Anxiety and depression are prevalent psychological disorders in adolescents, particularly among girls. This study aimed to investigate the association of the dietary inflammatory index (DII) and anthropometric/body composition indices with depression and anxiety in Iranian adolescent girls. Methods In this cross‐sectional study, 260 girls aged 15–18 years were recruited from high schools in Kashan, Iran. Dietary intake was assessed using a validated semiquantitative food frequency questionnaire (FFQ), and DII scores were calculated. Anthropometric indices and body composition, including body mass index (BMI), fat‐free mass (FFM), body fat mass (BFM), skeletal muscle mass (SMM), and waist‐to‐hip ratio (WHR), were measured using an InBody 770 analyzer. Depression and anxiety levels were evaluated using the DASS‐21 questionnaire. Logistic regression was applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs) across DII tertiles and body composition categories. Results No statistically significant associations were observed between DII tertiles and depression or anxiety in any of the adjusted models. Although higher DII scores were associated with increased odds of high BMI (OR: 1.62; 95% CI: 0.94–2.80), this association did not reach statistical significance. However, higher DII scores were significantly associated with increased odds of high BFM (OR: 2.28; 95% CI: 1.22–4.25) and low FFM (OR: 0.48; 95% CI: 0.26–0.89) in fully adjusted models. Moreover, higher BMI (OR: 3.55; 95% CI: 2.15–5.33), BFM (OR: 4.25; 95% CI: 2.34–6.20), and WHR (OR: 3.20; 95% CI: 1.62–4.89) were significantly associated with higher odds of depression. Likewise, increased WHR and BFM were positively linked to anxiety, whereas higher FFM was inversely associated with both depression (OR: 0.45; 95% CI: 0.24–0.83) and anxiety (OR: 0.58; 95% CI: 0.33–1.03). Conclusions While no direct association was found between DII and mental health outcomes, adolescents with higher DII scores tended to have unfavorable anthropometric profiles, which in turn were significantly associated with elevated risks of depression and anxiety. These findings highlight the potential mediating role of body composition in the relationship between DII and psychological health.