1 Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney School of Public Health, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia. Electronic address: emmanuel.stamatakis@sydney.edu.au.
2 Department of Social Medicine, CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, the Netherlands.
3 Department of Public Health and Nursing, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.