Food marketing near schools: content, permissibility, and associations with adolescents’ nutritional outcomes

Abstract Background The widespread marketing of unhealthy foods, as a component of an obesogenic food environment, may influence children’s food and taste preferences, and purchase requests, potentially contributing to overweight and obesity. This cross-sectional study examined the content and regulatory compliance of outdoor food advertisements surrounding upper secondary schools in Shiraz (the most populous metropolis in southern Iran) and explored their associations with students’ anthropometric outcomes. Methods All food advertisements within a 500-meter distance of 24 upper secondary schools were analyzed using photo-elicitation in MAXQDA 2020. Advertisements were classified by product food groups and marketing strategies and evaluated by Iran’s national list of health-threatening products, the WHO Eastern Mediterranean Region Nutrient Profile (WHO-EMR-P) Model, and the NOVA system. Anthropometric measurements were also collected from 656 students of the selected schools. Results A total of 423 food advertisements were identified, of which 67.85% promoted ultra-processed foods (UPFs). Nearly half of the advertisements (47.75%) used child-targeted marketing strategies, while 79.20% contained general marketing strategies. 76.1% were classified as non-permissible under the WHO-EMR-P model, compared with 48.9% under national criteria. Despite this notable difference, the most common unhealthy advertised products were extruded snacks and chips, ice cream, carbonated soft drinks, and other sugar-sweetened beverages. A higher density of school-level food advertisements were significantly associated with higher BMI z-scores (B = 0.008, P = 0.043) and greater odds of being in a higher BMI-for-age category (OR = 1.016, P < 0.001). These associations were stronger for advertisements promoting UPFs, particularly those using child-targeted marketing strategies (BMI z-score: B = 0.009 and 0.013; BMI-for-Age: OR = 1.019 and 1.025, respectively). Conclusion Outdoor food advertising around schools predominantly promotes ultra-processed and non-permissible products and is significantly associated with overweight and obesity among adolescents. These findings highlight the need to strengthen policies to protect children, restrict unhealthy food marketing, and create healthier school food environments.