The marketing of ultra-processed and discretionary foods on social media significantly influences dietary choices and consumer engagement, particularly among younger demographics (1). As investment by food brands in digital media increases, identifying the strategies used across various platforms becomes crucial for public health interventions and policy development. However, comparative analyses of these marketing strategies across multiple platforms remain scarce. This study aimed to examine marketing strategies used by leading food and beverage companies across four major social media platforms and assess their influence on consumer engagement. A comparative analysis of 1,000 posts (25 posts per company per platform) from ten internationally recognized food and beverage brands was conducted on Facebook, Instagram, TikTok, and X (formerly Twitter). Posts were manually categorized into one or more of eight predefined marketing strategies (2). Engagement metrics including likes, comments, and shares were collected, with non-parametric statistical tests used to identify differences in engagement across platforms, strategies, and brands (3). Corporate Social Responsibility (CSR) posts were the least frequent (0.7%) but generated the highest median engagement, particularly in comments (p < 0.001). In contrast, Affective Branding (33.5%) and Product Endorsement (29.9%) were the most used strategies but yielded only moderate engagement. Engagement differed significantly across platforms, with Instagram achieving the highest median likes (3307, p<0.001) and shares (416, p<0.005), while X recorded the lowest engagement overall. Brands such as McDonald's and Sour Patch Kids had significantly higher engagement levels compared to other brands (p < 0.001). These findings suggest public health campaigns and policymakers could effectively use emotionally engaging and socially responsible marketing strategies like those successfully employed by food brands, potentially improving consumer engagement and healthier dietary choices. Furthermore, the distinct differences in strategy effectiveness across platforms highlight the importance of tailored, platform-specific health promotion approaches. This study provides novel insights by systematically comparing digital food marketing strategies and consumer engagement across multiple major social media platforms and brands, contributing essential information for targeted public health initiatives and the development of digital marketing regulations.