Abstract
BACKGROUND: The study assessed the associations between dietary indices and anthropometric parameters in participants enrolled in the Third Age University (U3A) in Türkiye. METHODS: A cross-sectional study was conducted on 272 U3A participants. Dietary quality was assessed using the Healthy Eating Index-2015 (HEI-2015), Diet Quality Index-International (DQI-I), and Household Dietary Diversity Score (HDDS), which were calculated from 24-h dietary recall data. Adherence to the Mediterranean diet was evaluated using the Mediterranean Diet Adherence Scale (MEDAS). Anthropometric and body composition measurements were collected. All analyses controlled for relevant socio-demographic factors and nutrition education. RESULTS: Higher scores for both DQI-I and HDDS were linked to lower body mass index and waist circumference (all p < 0.05). Further, greater adherence to the Mediterranean diet was inversely associated with body fat percentage, with participants exhibiting higher adherence having a lower likelihood of increased body fat percentage (OR = 0.831; %95CI: 0.697–0.989; p < 0.05). CONCLUSION: Diet quality among participants in U3As was predominantly moderate to high. Taken together, these findings indicate that high adherence to the Mediterranean diet and higher dietary diversity may be linked to improvements in anthropometric measurements and a reduced risk of obesity in this population. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-026-26268-w.