Associations of the dietary inflammatory index, flavonoid intake, and dietary total antioxidant capacity with obesity and adiposity indicators among adults receiving outpatient nutritional care

Abstract Purpose To investigate the associations of the Dietary Inflammatory Index (DII), flavonoid intake (FI), and Dietary Total Antioxidant Capacity (DTAC) with obesity as defined by the 2025 diagnostic criteria, and with indicators of total and central adiposity in adults receiving outpatient nutritional care. Methods This cross-sectional study included 183 adults attending a nutrition outpatient clinic in southwestern Paraná, Brazil (2023–2024). Sociodemographic, clinical, anthropometric, and dietary data were obtained from nutritional records. DII, FI, and DTAC were energy-adjusted per 1,000 kcal/day. Total and central adiposity were assessed by body fat percentage (BF%), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR). Associations were examined using crude and adjusted linear and binary logistic regression models. Results The sample was predominantly female, with a median age of 32 years. Obesity prevalence increased from 41.0% when defined by body mass index (BMI) to 64.5% according to the 2025 diagnostic criteria. Participants in the lowest DII tertile had lower BF% than those in the second tertile, although this difference was no longer significant after adjustment. In adjusted models, higher BF% (β = -0.418; 95% CI: -0.811 to -0.025; p = 0.037) and WC (β = -0.002; 95% CI: -0.004 to -0.001; p = 0.008) were associated with lower FI. No independent associations involving DII or DTAC were observed after adjustment. Conclusion DII, FI and DTAC were not associated with obesity. However, higher BF% and WC were associated with lower FI, highlighting the potential relevance of these bioactive compounds in adults receiving outpatient nutritional care.