Contribution of habitual and meal-specific dietary inflammatory index and its associations with obesity and metabolic risk indicators in women

Inflammatory diets are associated with obesity and cardiometabolic dysfunction, nevertheless, it remains unclear whether overall dietary inflammation or the timing of pro-inflammatory meals yields a greater metabolic impact. This study utilizes the energy-adjusted dietary inflammatory index (EDII) to examine associations of both habitual/meal-specific with metabolic risk among women. In this cross-sectional study, 562 Iranian women (aged 20–60) from Tehran were assessed. Habitual and four meal-specific EDII scores (breakfast, lunch, afternoon snacks, dinner) were calculated from three non-consecutive 24-hour dietary recalls using 29 pro- and anti-inflammatory parameters. Anthropometric variables, fasting blood assays, body mass index (BMI), Visceral Adiposity Index (VAI), Cardiometabolic Index (CMI), and Atherogenic Profile Index (API) were measured. Multivariable linear and logistic regression models, adjusted for potential confounders, were used to estimate associations. Habitual-EDII showed the strongest association with afternoon snack-EDII (R² = 0.36), followed by Dinner (0.29), Lunch (0.25), and Breakfast (0.20). Habitual-EDII in T (tertile) 3 vs. T1 was associated with increased odds of overweight/obesity BMI [OR 2.38, 95% CI (1.51–3.81)], CMI [1.95 (1.23–3.04)], VAI [1.92 (1.21–3.03)], and API [2.53 (1.57–4.08)]. Afternoon snack-EDII was associated with higher odds of overweight/obesity [OR 1.93 (1.21–3.11)]. Finally, dinner-EDII was associated with an elevated risk of VAI [OR 1.85 (1.17–2.92)] and CMI [OR 1.77 (1.12–2.80)]. Pro-inflammatory diets, especially during afternoon and dinner, are strongly associated with cardiometabolic risk, highlighting a meal-specific inflammation relationship. Accordingly, prospective cohort studies and interventions studies are required to confirm the veracity of these findings.