Objective: To investigate the association between dietary behaviors and overweight and obesity among middle school students, so as to provide the evidence for developing dietary intervention strategies for them. Methods: From October to December 2023, a total of 7 063 middle school students from six counties (districts) in Ma'anshan City, Anhui Province were selected through stratified cluster random sampling method. Demographic information, physical activity, sleep, and dietary behaviors over the past year were collected through questionnaire surveys. Height and weight were measured to calculate body mass index (BMI), with overweight and obesity determined based on gender- and age-specific BMI cut-off points. The association between dietary behaviors and overweight and obesity was analyzed using a multivariable logistic regression model. Results: Totally 7 063 questionnaires were allocated, and 7 045 valid questionnaires were recovered, with an effective recovery rate of 99.75%. There were 3 925 males (55.71%) and 3 120 females (44.29%). A total of 2 326 students were overweight and obesity, with the prevalence of 33.02%. There were significant differences in the prevalence of overweight and obesity among middle school students with different genders, whether they were the only child or not, different intake frequency of sugar-sweetened beverages, and different intake frequency of beans and soy products (all P<0.05). After adjusting for factors such as gender, education stage, whether the only child, whether living on school, physical activity and sleep, multivariable logistic regression analysis showed that the frequency of snack consumption (1-2 times/week, OR=0.803, 95%CI: 0.669-0.963; 3-6 times/week, OR=0.759, 95%CI: 0.623-0.926; daily, OR=0.758, 95%CI: 0.595-0.964), sugar-sweetened beverages consumption (1-2 times/week, OR=1.166, 95%CI: 1.012-1.343; daily, OR=1.891, 95%CI: 1.302-2.746) and beans and soy products consumption (1-2 times/week, OR=0.787, 95%CI: 0.628-0.987) were the influencing factors of overweight and obesity among middle school students. Conclusions The frequencies of snack, beans and soy products and sugar-sweetened beverage consumption are associated with overweight and obesity among middle school students. Targeted interventions should be strengthened to reduce the risk of overweight and obesity.