Helen L. Walls, PhD, MPH(Hons) is a Research Fellow at the London School of Hygiene and Tropical Medicine and the Leverhulme Centre for Integrative Research on Agriculture and Health. She was formerly an NHMRC Sidney Sax Public Health Fellow with The Australian National University, and has worked with the World Health Organization and New Zealand Ministry of Health. Her research interests include food systems, nutrition and health, with a particular focus on trade and agricultural policy, and also trade in health services, medical tourism and migration. She is an associate editor of the journal BMC Obesity.