Food production and consumption is causing environmental harm such as climate change and a decline in ecosystem services. Hence, a transformation of the food system is necessary for humanity’s future well-being. The public meal can be used as a tool for establishing healthy and sustainable eating habits at an early age and contribute to changed dietary choices in the future, yet few municipalities are prioritizing this opportunity. This study uses Södertälje municipality as a case to look at the change process of implementing a sustainable diet concept in preschools, schools, and gymnasiums, with the hope of acquiring knowledge and understanding useful for similar cases of transformation. Using a framework for deliberate social-ecological transformations and data primarily from qualitative interviews, I map the phases of transformation to better understand how agency and opportunity context have been used in navigating the process and identify possible opportunities going forward. Findings show the importance of political support, an integrated organization, and rooting new practices amongst the officials. The motivation and persistence of a key leader was crucial in navigating forward, and the process has been driven by several opportunities such as a political window of opportunity for change and the collaboration with a bridging organization in developing a food concept. It also shows how municipalities can have an important role in changing eating habits and how food-related norms and values can potentially shift and contribute to long-term food system change.