Bai is specialised in the development and evaluation of complex health interventions in LMICs. She has co-authored with policy makers from 46 countries and led multi-nation, inter-discipline research projects to generate impactful scientific outputs used by international bodies eg WHO, United Nations, World Obesity Federation, Asian Development Bank, the State Council of China and Switzerland Federal Food Safety Office. She has a track record of leading international advocacy and methodological innovations of methods rooted in systems science. She leads the SYSTAM International Consortium, comprising Ministries of Health in the SEA region and WHO offices to develop and monitor systemic, national level interventions tackling all forms of malnutrition. She led methodological innovations to systems methods for tackling multiple global challenges simultaneously. She led the development and publication of the first reporting guidance for public health intervention projects underpinned by a systems approach. She designed and co-edited the first journal collection dedicated to systems approach to tackling global nutrition challenges (72 authors from 13 countries). She has chaired international symposia in different countries to share the 1st empirical experience of applying a systems approach to nutrition interventions in HICs and LMICs. She led the evaluation of the world's first, multi-setting regulatory intervention on sedentary behaviour among children, providing the first, real-world evidence for regulatory interventions on sedentary behaviour. 

Bai's contributions to global health and behavioural medicine have been recognised by prestigious awards from the ISBNPA, The Lancet, UKSBM and UKCO. Bai won the 2024 Practice Leadership Award from the Sedentary Behavioural Research Network (SBRN).

Bai leads the City Futures Theme at the Cabot Institute for the Environment.