With billions of users worldwide, social media has become a powerful force in shaping lifestyle behaviors, including physical activity (PA), particularly among young adults. This narrative review examined the growing role of social media–driven interventions in pro- moting PA among young adults at risk of obesity. We analyzed the application of behavior change theories, including Social Cognitive Theory, the Theory of Planned Behavior, the COM-B, and specific behavior change techniques, alongside the role of intersectionality in shaping intervention effectiveness. Platform-specific strategies across Instagram, Tik- Tok, YouTube, and Facebook were summarized, highlighting engagement mechanisms, personalized content delivery, and behavior change approaches that influence behavioral, physiological, and motivational outcomes. Despite these opportunities, challenges such as ethical concerns, misinformation, accessibility barriers, and quality control issues remained significant. Finally, future directions were outlined, including integration with wearables, AI-driven multi-platform strategies, co-designed interventions, and policy frameworks to optimize digital health promotion. In conclusion, social media offers considerable poten- tial as a cost-effective, accessible tool for promoting PA and preventing obesity in young adults, though effectiveness is limited by misinformation, unregulated content, and poor quality control

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