Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, St. Mary's Campus, Norfolk Place, Paddington, London, W2 1PG, UK. d.aune@imperial.ac.uk. Department of Nutrition, Bjørknes University College, Oslo, Norway. d.aune@imperial.ac.uk. Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital Ullevål, Oslo, Norway. d.aune@imperial.ac.uk. Institute for Biometry and Epidemiology, German Diabetes Center, Leibniz Institute for Diabetes Research at the Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany. Department of Epidemiology and Preventive Medicine, Regensburg University Medical Center, Regensburg, Germany. Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital Ullevål, Oslo, Norway. Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, St. Mary's Campus, Norfolk Place, Paddington, London, W2 1PG, UK. Department of Public Health and Nursing, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.