BACKGROUND: Many patients are already malnourished when admitted to hospital. Barriers and facilitators to nutrition care in hospital have been identified and successful interventions developed; however, few studies have explored how to sustain and spread improvements. The More-2-Eat phase 1 study involved five hospitals across Canada implementing nutrition care improvements, while phase 2 implemented a scalable model using trained champions, audit and feedback, a community of practice with external mentorship and an implementation toolkit in 10 hospitals (four continuing from phase 1). Process measures showed that screening and assessment from phase 1 were sustained for at least 4 years. The objective of this study was to help explain how these nutrition care improvements were sustained and spread by understanding the role of the trained champions, and to confirm and expand on themes identified in phase 1. METHODS: Semistructured telephone interviews were conducted with champions from each phase 2 hospital and recordings transcribed verbatim. To explore the champion role, transcripts were deductively coded to the 3C model of Concept, Competence and Capacity. Phase 2 transcripts were also deductively coded to themes identified in phase 1 interviews and focus groups. RESULTS: Ten interviews (n=14 champions) were conducted. To sustain and spread nutrition care improvements, champions needed to understand the Concepts of change management, implementation, adaptation, sustainability and spread in order to embed changes into routine practice. Champions also needed the Competence, including the skills to identify, support and empower new champions, thus sharing the responsibility. Capacity, including time, resources and leadership support, was the most important facilitator for staying engaged, and the most challenging. All themes identified in qualitative interviews in phase 1 were applicable 4 years later and were mentioned by new phase 2 hospitals. There was increased emphasis on audit and feedback, and the need for standardisation to support embedding into current practice. CONCLUSION: Trained local champions were required for implementation. By understanding key concepts, with appropriate and evolving competence and capacity, champions supported sustainability and spread of nutrition care improvements. Understanding the role of champions in supporting implementation, spread and sustainability of nutrition care improvements can help other hospitals when planning for and implementing these improvements. TRIAL REGISTRATION NUMBER: NCT02800304, NCT03391752.