Jean-Michel Oppert, MD, PhD, is Professor of Nutrition at Sorbonne University, Paris, France. He is head of the Department of Nutrition at Pitié-Salpêtrière university hospital (AP-HP) in Paris which is focused on advanced care of patients with severe obesity. His current research interests include the measurement and role of physical activity and sedentary behaviour in health and disease, especially metabolic diseases, and the investigation of urban environmental determinants of physical activity and diet. He has been or is involved in a number of EU and national projects on these topics and is author or co-author of more than 250 papers in the peer-reviewed literature on nutrition, physical activity and obesity. Professor Oppert is past president (2009-12) of the European Association for the Study of Obesity (EASO).