Objective  To investigate the prevalence and influencing factors of overweight and obesity among primary and middle school students and to provide evidences for developing effective intervention measures.

  Methods  A survey on overweight and obesity and their influencing factors was conducted among 5 306 students selected with multistage cluster sampling in 8 primary and middle schools in an urban district of Chongqing city from December 2018 to January 2019. The national standards were adopted to assess overweight and obesity in the study.

  Results  The prevalence rate of overweight and obesity were 14.93% and 9.18%, respectively. The rate of overweight and obesity in the boy students were significantly higher than those in the girl students (15.87% vs. 13.92% and 10.88% vs. 7.35%) (both P < 0.05); the overweight rate of junior middle school students was significantly higher than that of primary school students (16.53% vs. 13.10%, P < 0.05); but the obesity rate of senior middle school students was significantly lower than that of primary school students (7.71% vs. 10.85%, P < 0.05). Multivariate logistic regression analysis revealed following significant impact factors of overweight and obesity among the students: gender, weekend sleeping time, whether being an only child, parental body type, parents′ screening time, whether having a reduced exercise time due to studies assigned by parents, eating speed, whether having breakfast, and frequency of milk (soy milk) consumption.

  Conclusion  The prevalence rate of overweight and obesity are higher than those of national average and mainly influenced by familial and parental factors and individual dietary habits among primary and middle school students in urban regions of Chongqing city and targeted intervention measures on overweight and obesity should be implemented in the students.