TikTok is a global social media platform popular with young people, encouraging viewers to engage with user-generated video content (through likes, shares and comments) and mimic displayed behaviours (by creating similar videos or content). It is therefore a powerful and engaging tool that has potential for the widespread dissemination of information (or misinformation) and to influence behaviours. Social media is saturated with the promotion of ‘diet culture’ and has a strong influence on the eating behaviours of young people (1,2). This is concerning as childhood and adolescence are critical periods of growth requiring optimal nutrition (3). This study aimed to investigate how dieting is portrayed on TikTok and consider the potential implications for public health. A cross-sectional descriptive content analysis was undertaken of 50 videos from each of the five most popular diet-related hashtags (#diet, #whatieatinaday, #wieiad, #dietitian, #diettips). A codebook was developed to analyse the body-related content referenced (weight measurement, calories, body image, body checking, body comparisons over time) and collect the engagement for each video (likes, comments and shares). Overall, the 250 videos contributed to a total of 197.2 million likes (M = 789,051.0, SD = 923,335.0), 126,7251 comments (M = 5,069.0, SD = 9,315.3), and 3.8 million shares (M = 15,423.2, SD = 41,271.3). Most videos featured adults (n = 205, 82%), and only a small number of videos featured identifiable children or adolescents (n = 16, 6.4%). The information and advice regarding diets and eating behaviours came from two types of sources: 'experts’ and regular creators sharing their personal experience. Almost half of the videos were educational or instructional (n = 116, 46.4%), of which 74 (63.8%) were posted by users who claimed expert status. The most common titles by those claiming to be experts were “dietitian” (n = 43, 58.1%), “health and wellness coach” (n = 7, 9.5%), “doctor” (MD; n = 6, 8.1%), “fitness trainer” (n = 6, 8.1%), and “nutritionist” (n = 3, 4.1%). Of the videos that specifically mentioned a certain diet, the most common diets were low calorie (n = 32, 12.8%), vegan (n = 14, 5.6%), self-reported healthy eating (n = 12, 4.8%), and fasting (n = 10, 4.0%). The use of humour was the only feature significantly associated with engagement. Health professionals are presented with a unique opportunity to widely and positively influence the public by utilising the popularity of TikTok amongst young people to disseminate evidence-based information and promote healthy eating behaviours. Our findings suggest that experts using authentic, humorous, and engaging personas would be more likely to be popular on this platform.