Urban–Rural Disparities in the Association Between Dietary Patterns and Physical Fitness Among Chinese Children, Adolescents, and Young Adults

<b>Background:</b> This study aimed to examine the associations between dietary patterns and physical fitness among Chinese children, adolescents, and young adults, and to investigate the differences in dietary patterns and physical fitness between urban and rural Chinese children and adolescents. <b>Methods:</b> The data were obtained from the Chinese National Survey on Students' Constitution and Health (CNSSCH). The final analysis included 200,276 participants from fourth grade to the fourth year of undergraduate study from urban and rural China. Statistical analyses were conducted using the R software (version 4.4.3). Group differences were examined using <i>t</i>-tests, and multivariable linear regression models were applied to evaluate associations between dietary patterns and physical fitness indicators, adjusting for sex, educational stage, socioeconomic status, and physical activity. Interaction terms were included to assess urban-rural differences. <b>Results:</b> Regular consumption of breakfast, eggs, and dairy products was positively associated with muscular strength, endurance, flexibility, and speed (<i>p</i> < 0.05), while higher intake of sugar-sweetened beverages was negatively associated with flexibility and muscular performance (<i>p</i> < 0.001). These associations were stronger among rural students, who benefited more from healthy dietary patterns but were also more vulnerable to the adverse effects of sugary beverages on BMI, lung capacity, and strength. <b>Conclusions:</b> This study explored the associations between dietary patterns and physical fitness among children, adolescents, and young adults in Chinese urban and rural areas. Our findings suggest that regular consumption of breakfast, eggs, and dairy products is positively associated with muscular strength, speed, endurance, and coordination, whereas frequent intake of sugary beverages is associated with poorer physical fitness. These associations appeared to differ between urban and rural populations: rural students may benefit more from nutrient-rich dietary patterns but also seem more vulnerable to the adverse associations of sugary beverages.