Background: Dietary Guidelines are an important tool for population health promotion efforts. However, current surveillance data suggest that only a small minority of the population meet the 2014 Brazilian Dietary Guidelines (BDG) recommendations. Translating recommendations into practice may not be immediately clear and behaviorchange messages guiding the behaviors that need to be changed and identifying substitute practices to meet a specific recommendation, are required. This study details the methods undertaken to develop and refine messages supporting the adoption of healthy dietary choices and behaviors in adults, as outlined in the BDG. Methods: A sequential, five-step, mixed-methods approach, determined a priori, was followed for designing and refining messages. These included: (1) content extraction; (2) audience analysis; (3) input from an expert review panel; (4) message development and message refinement; and a (5) test of content validity. Results: The content extraction process led to the identification of 63 excerpts from the BDG, organized into themes. The audience analysis highlighted barriers to healthy eating that included lack of time (to eat, to cook), difficulty in accessing healthy food, the convenience and the ubiquitous marketing of ultra-processed foods. Twenty of the 63 DG excerpts reviewed by the expert panel were identified as being a priority for message development and total of 111 messages were developed. Messages were short, structured to be one-sided, conveyed the most important information at the beginning (anticlimactic), used simple language and were explicit in the information they relayed. They were positive and gain-framed and used an empathetic, solution-or substitution-based tone and were presented in the active voice. The messages focused on goals and skill development, behavior regulation, incentivized positive practices as time and/or cost saving. Content validity testing helped further messages and reduced the number of messages from 111 to 40.