Background Adolescents are increasingly exposed to online health information promoting supplements as quick solutions for weight management and muscle development, raising public health concerns. Objective This study investigated whether online media engagement—weight-and fitness-related information-seeking behaviors and the internalization of online appearance ideals—predicts adolescents' online purchasing of weight-loss and muscle-building products, with attention to differences between girls and boys. Methods A cross-sectional online survey was conducted among 1,526 Czech adolescents (50% girls) aged 13–18 years ( M = 15.4, SD = 1.7). Measures included self-reported online weight- and fitness-related information-seeking behaviors, internalization of online appearance ideals (thin-ideal among girls; muscular ideal among boys), and online purchasing of weight-loss and muscle-building products. Hierarchical regression analyses were conducted separately for girls and boys, controlling for sociodemographic and body image variables. Results Overall, 4.1% (63/1,521) purchased weight-loss and 19.1% (303/1,524) purchased muscle-building products online. For both girls and boys, greater engagement in seeking weight- and fitness-related information was associated with purchasing both product types. Internalization of online appearance ideals was significantly associated with muscle-building but not weight-loss product purchases. Conclusion Findings highlight a novel pathway through which online media may shape youth consumer choices, pointing to the need for media literacy and body image-informed strategies to promote safer decision-making.
Hayriye Güleç (2026) studied this question.