Abstract PROJECT SUMMARY Mika Matsuzaki, PhD, MPH, MS, is an Assistant Professor of Human Nutrition in the Department of International Health at the Johns Hopkins Bloomberg School of Public Health (BSPH). She seeks a K01 Award to gain skillset, knowledge, and mentored research experiences through exposure to diverse aspects of food systems and systems science research. This award is a critical step for her to complete the career transition into an independent scholar contributing new insights on systemic interventions to prevent and reduce youth obesity across all populations. The proposed training and study build upon her strong training in nutritional epidemiology, school nutrition policies, and food environments using advanced statistical techniques. The training will build her expertise in the use of mixed-methods, systems science approaches including simulation models examining school-centric food systems and youth obesity. Obesity is increasingly recognized as a systems problem, requiring multi-level, multi-component solutions. Previous research, including my own, has shown that at the population level, youth obesity disproportionately affects various sociodemographic groups. Given the persisting disparities in youth obesity, novel solutions need to be developed. To this end, the proposed study will seek ideas for such solutions through examination of factors within food systems that may have contributed to unexpectedly low obesity prevalence seen in a handful of schools (Aim 1), which we call positive deviators. We will then estimate the potential impact of introducing new changes in food systems to improve diet for students in other school settings in simulation models (Aim 2). Dr. Matsuzaki has access to an excellent research environment and renowned scholars at Johns Hopkins University (JHU) as well as at her collaboration institutions, San Francisco State University (SFSU) and the City University of New York (CUNY). She has built a strong mentoring team covering all training and research components with Dr. Joel Gittelsohn, PhD, MPH (BSPH, primary mentor); co-mentors Dr. Emma Sanchez-Vaznaugh, ScD, MPH (SFSU), Dr. Jess Fanzo, PhD (JHU), Dr. Bruce Y. Lee, MD, MBA (CUNY), and Dr. Takeru Igusa, PhD (JHU). Dr. Matsuzaki will gain hands-on experiences through her proposed research in systems science and youth obesity while obtaining necessary content expertise and experiences through regular meetings and study activities with her mentors, courses, workshops, seminars, scientific meetings. The K01 mentored research training and experience will enable Dr. Matsuzaki to achieve independent scholarship with expertise in systems science approaches to youth obesity disparities and an ability to design and conduct large-scale simulation studies and develop and test new systemic interventions in subsequent R01 studies.