Background <p>The sustainment of effective, scaled-up public health interventions is key to ensuring that resources are not wasted and opportunities to improve population health maintained. An initial typology of practical approaches to sustain interventions were developed, however it is unknown how frequently these approaches are applied in the real world. This study aimed to explore how scaled-up obesity preventions interventions have addressed sustainment and whether their sustainment approaches could be classified into the sustainment typologies.</p> Methods <p>Building on previously published study that identified 90 obesity prevention interventions scaled up to at least city-wide level, we extracted relevant information from each of the interventions pertinent to their development, funding, delivery, magnitude of scale and length of sustainment. Interventions were further coded into one of two sustainment typologies, that is self-sustainment and supported sustainment. Descriptive statistics were used to describe the characteristics of the intervention and their sustainment approach.</p> Results <p>From the dataset of 90 interventions, a quarter of the interventions were identified as using the ‘self-sustainment’ approach, with the remaining three quarters of interventions coded as ‘supported sustainment’. Self-sustaining interventions were mostly delivered and funded by private or community organisations while supported sustainment interventions were government organisations. Over a third of the supported sustainment interventions had been found to be scaled up without prior research.</p> Conclusions <p>This hypothesis generating study revealed the presence of self-sustained and externally supported approaches to sustainment with some differences. Self-sustaining interventions were found to employ a commercialisation strategy to facilitate their sustainment and were delivered at larger magnitudes of scale. In contrast, supported interventions were mostly developed and delivered by government organisations and delivered at smaller magnitudes of scale. Our results suggests that government developed and delivered interventions tend to remain dependent on ongoing government support, rather than evolving into self-sustaining models. It is also concerning that governments may be supporting the sustainment of interventions where their evidence base is questionable. Importantly, future research needs to explore the characteristics of programs that are sustained and identify the most effective strategies for supported sustainment.</p>