The current global food system does not work for people, our planet, and prosperity. It is under threat from a range of factors, including COVID-19, climate change, and conflict. Therefore, food systems transformation is urgently needed. In order to succeed, the impacts of food systems interventions must be maintained in the long-term. Short funding cycles limit the scope for long-term evaluation. Often, short-term impacts are assumed to reflect sustained change, but the dynamic nature of food systems means that, in reality, short- and longterm impacts may be different. There is an urgent need to know what works in the long-term to achieve food systems transformation, who it works for, and what it costs.