Warning labels on ultra-processed foods increased correct identification rates from 54% to 70% among Latino adults in a randomized trial of 4,107 participants. Both simple "WARNING: Ultra-processed food" labels and detailed health warnings mentioning weight gain and diabetes risks significantly improved recognition compared to standard barcode labels. The warnings also reduced perceived healthfulness and purchase intentions while increasing perceived message effectiveness. This represents meaningful progress in consumer education about ultra-processed foods, which comprise roughly 60% of American calories and correlate with increased chronic disease risk. The finding is particularly relevant given that Latino populations face disproportionate rates of diabetes and obesity. However, the study only measured immediate responses to product images, not actual purchasing behavior or long-term dietary changes. Additionally, the health warning's effectiveness varied by education level and English proficiency, suggesting implementation challenges. As a preprint awaiting peer review, these results require validation before informing policy. The research adds incremental but valuable evidence for front-of-package labeling initiatives, though real-world effectiveness depends on regulatory adoption and sustained consumer response over time.