To investigate the awareness rate and influencing factor of weight management knowledge, and the prevalence of abnormal body mass index (BMI) among junior high school students in Yinchuan, analyze the correlation between weight management knowledge awareness and abnormal BMI, and provide a theoretical basis for the implementation of weight-related health education among children and adolescents.

Between March 12 and April 26, 2025, a multi-stage stratified cluster random sampling method was employed to recruit 2 485 students from Grade 7 to Grade 9 across 9 junior high schools in Yinchuan as study participants. A self-developed structured questionnaire was administered to assess participants’awareness of comprehensive weight management knowledge (including nutrition, physical activity, etc.) and its associated influencing factors. Abnormal BMI was screened using a bioelectrical impedance analysis (BIA) body composition analyzer. In accordance with the national standards Screening for Malnutrition in School-age Children and Adolescents (WS/T456-2014)and Screening for Overweight and Obesity in School-age Children and Adolescents (WS/T586-2018) issued by the National Health and Family Planning Commission of China, students with emaciation, overweight, or obesity were classified by gender and age.

The overall awareness rate of weight management knowledge among junior high school students in Yinchuan was 57.34%. The highest awareness rate was observed in the dimension of “prevention cognition” (51.75%), while the lowest was in “scientific weight control” (35.57%). No statistically significant difference was detected across different grades (P>0.05),whereas the awareness rate among female students was significantly higher than that among male students (P<0.05).Multivariable logistic regression analysis revealed that female gender (OR=0.53), Grade 9 enrollment (OR=1.21), urban residency (OR=0.78), being an only child (OR=1.31), parental education level of college or above (OR=1.18), cohabitation with parents (OR=2.21), normal guardian weight (OR=0.84), school-based health education implementation (OR=1.33), and teacher-delivered weight management knowledge (OR=2.61) were significant influencing factors of weight management knowledge awareness among junior high school students (all P<0.05). The prevalence of abnormal BMI among the study population was 29.86%, with emaciation, overweight, and obesity accounting for 8.09%, 14.29%, and 7.48% of the total sample, respectively.The awareness rate of weight management knowledge was significantly negatively correlated with emaciation (r=-0.712),overweight (r=-0.723), and obesity (r=-0.756), with all P<0.05.

The overall awareness rate of weight management knowledge among junior high school students in Yinchuan is relatively low, while the prevalence of abnormal BMI is notably high. A significant negative correlation exists between weight management knowledge awareness and abnormal BMI, which warrants serious attention.