Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 54 9 2025 10 04 1954 1964 Pınar Hamurcu Department of Nutrition and Dietetics, Faculty of Health Sciences, Istinye University, Istanbul, Türkiye 2024 03 04 2025 05 09 Background: This study aimed to examine the relationship between nutritional status assessed by the diet quality index with physical activity, sleep, and quality of life among young adults. Methods: This descriptive, cross-sectional research utilized a sample of 700 university students enrolled in the 2021–2022 academic year at a private university's Faculty of Health Sciences in Istanbul, Türkiye. Data were collected using face-to-face interviews with Information Form, Pittsburgh Sleep Quality Index (PSQI), International Physical Activity Questionnaire (IPAQ), World Health Organization Quality of Life-Short Form-Turkish Version (WHOQOL-BREF-TR) and 24-Hour Food Consumption Record. The dietary quality of the participants assessed via Diet Quality Index-International (DQI-I). Results: The study revealed inadequate diet quality among young adults, with a mean DQI-I score of 33.08±7.03. According to PSQI assessment, 85.3% of them had impoverished sleep quality, and according to IPAQ assessment, 23.3% of them were physically inactive. In comparing participants' characteristics with DQI-I, a positive correlation observed between age and both DQI-I-Total (P=0.017) and Variety sub-dimension (P=0.027). Furthermore, statistically significant differences identified between Moderation sub-dimension and economic situation (P=0.032), as well as between Variety sub-dimension and sleep duration (P=0.044). No statistically significant association found between diet quality and either sleep quality or physical activity levels (P>0.05). However, a significant relationship observed solely between Variety sub-dimension and social relationship sub-dimension of WHOQOL-BREF-TR (P=0.033). Conclusion: This study observed a significant correlation between dietary diversity and quality of life, whereas no significant correlation observed between diet quality and sleep quality, physical activity level, or quality of life. https://ijph.tums.ac.ir/index.php/ijph/article/view/34811 https://ijph.tums.ac.ir/index.php/ijph/article/download/34811/8651