Suboptimal dietary patterns are a leading risk factor for noncommunicable disease(1) and only 2.1% of Australian young adults aged 18-24 years meet recommended fruit and vegetable intakes(2). Raising awareness through evidence-based nutrition messaging is an important step towards improving dietary behaviours. Social media provides an important channel for delivering nutrition information to young adults(3), but limited evidence has been synthesised regarding the message characteristics that contribute to appeal and influence within this population. This systematic literature review explores characteristics that make nutrition messages on social media appealing to and influential for young adults, to create strategies for designing evidence-based nutrition messages for young adults on social media. Database searches were carried out in April 2026 across APA PsychInfo, Psychology & Behavioral Sciences Collection, CINAHL, PubMed, Web of Science, and Scopus (PROSPERO registration CRD420251266421). Eligible studies examined the characteristics of nutrition messages on social media that impacted appeal and influence among a young adult (18-25 years) population. Quantitative, qualitative and mixed methods studies were included. Screening, data extraction and quality appraisal were all conducted in duplicate. From 6089 articles, 17 full-text articles were included, representing four mixed-method studies, five qualitative studies, eight quantitative studies, and a total of 1840 young adults. Studies focused on Instagram, Facebook, Twitter or social media more broadly. Appealing and influential nutrition messages were described as those that had a credible source (e.g. health professional), were evidence-based (e.g. included references), contained information about health benefits (immediate rather than long-term), provided relevant and relatable content with practical tips, used informal/friendly language, were entertaining, and used image- and video-based formats. Nutritionists and Dietitians can implement these principles when developing nutrition content for social media, to improve the appeal and influence towards young adults. These findings may also inform the communication of national public health nutrition guidance, such as the revised Australian Dietary Guidelines, to young adults.