He worked as nutrition epidemiologist for TNO-nutrition, the main Dutch research institute for nutrition-related research (1989-1991). He was granted a fellowship from the Dutch Cancer Society and worked for this Society until 1994 after which he started his PhD research at the Department of Health Education and Promotion of Maastricht University. He obtained his PhD in Health Sciences in 1997 and subsequently worked as associate professor in health psychology and later as dean of the faculty of social sciences at the Netherlands Open University. From 2000-2002 Hans Brug was professor of Nutrition Education and director of education at the Faculty of Health Sciences, Maastricht University. From 2002 to early 2007 Brug was professor of Determinants of Population Health at the Department of Public Health, Erasmus University Medical Center, Rotterdam. From 2007 to April 2012 he was the director of the EMGO Institute for Health and Care Research at the VU University Medical Center.
Brug is past president of the International Society of Behavioral Nutrition and Physical Activity and is a member of the editorial boards of the International Journal of Behavioral Nutrition and Physical Activity, the Journal of Nutrition Education and Behavior, the American Journal of Health Promotion, and the Journal of Human Nutrition and Dietetics. Brug is a member of the Netherlands Academy for Nutrition Science and is a registered Epidemiologist and Nutrition Scientist.