Bai is known for her unique expertise in the development and evaluation of complex health interventions in both developing and developed countries, with a track record of international advocacy and methodological innovations of methods rooted in system science. She is the funder and leader of the SYSTAM International Consortium, comprising Ministries of Health and WHO offices to develop and monitor systemic interventions tackling global syndemic. She led methodological innovations to systems methods for tackling malnutrition in all its forms in 12 Asian countries. These innovations are endorsed by the WHO headquarters and 6 Ministries of Health for international applications. She led the first systematic review and analysis of national nutrition surveillance programmes in 19 SEA countries to inform research and capacity building. she conceived and led the development and publication of the world’s first reporting guidance for public health intervention projects underpinned by a systems approach. As the chief Guest Editor, she designed and edited the first journal collection dedicated to systems approach to tackling global nutrition challenges (72 authors from 13 countries across 4 continents, >10 million article views and downloads internationally). She organised and chaired international symposia in different countries to share the first empirical experience of applying a systems approach to nutrition interventions from China, Southeast Asia, South Pacific, and the Middle East. She led the evaluation of the world’s first, multi-setting regulatory intervention restricting sedentary behaviour among children and adolescents, providing the first, real-world evidence for regulatory interventions on sedentary behaviour. Bai was the only invited expert from the UK to join The Lancet’s Expert Consultation Meeting in Wuhan to review The Lancet Commission Report on ‘The Global Syndemic of Obesity, Undernutrition, and Climate Change’.