Obesity-related knowledge, practices, and BMI-for-age status among adolescent senior secondary school students in Bwari Area Council, Abuja, Nigeria: a cross-sectional study.

Abstract Background Adolescent nutritional assessment requires age- and sex-specific interpretation because undernutrition and excess adiposity may coexist during growth. Objective This study examined obesity-related knowledge, obesity-related practices, and BMI-for-age status among adolescent senior secondary school students in Bwari Area Council, Abuja, Nigeria. Methods A school-based cross-sectional study was conducted among students aged 13–19 years. Of 410 records in the raw dataset, seven students older than 19 years and two records with biologically implausible BMI-for-age z-scores were excluded, leaving 401 participants. Knowledge and practice were scored using 10-item scales and categorized with Bloom's cut-offs. BMI was recalculated from measured weight and height and classified using WHO BMI-for-age references. Associations were assessed using chi-square tests and multinomial logistic regression. Results Mean age was 15.50 years (SD 1.19). Knowledge was poor in 25.2%, moderate in 51.9%, and good in 22.9% of participants. Practice was poor in 74.1%, moderate in 23.9%, and good in 2.0%. BMI-for-age classification showed thinness in 11.7%, normal status in 79.6%, overweight in 7.2%, and obesity in 1.5%. Knowledge category was not associated with practice category (p = 0.269). The overall multinomial model for BMI-for-age status was not statistically significant (p = 0.257). Conclusion Thinness and excess BMI-for-age coexisted in this school-based adolescent sample. School health promotion in this setting should link nutrition education with feasible dietary, physical activity, and school-environment strategies.