His research is focused on the identification of individuals at increased risk of overweight, metabolic syndrome, type 2 diabetes, and atherosclerotic cardiovascular diseases and the prevention of these diseases and conditions by increasing physical activity and improving diet since childhood. He is a Principal Investigator in the Physical Activity and Nutrition in Children (PANIC) study and a Co-Principal Investigator in the Stop Diabetes (StopDia) study and the Dose Responses to Exercise Training (DR’s EXTRA) study. He has also acted as a senior researcher in many other large-scale lifestyle intervention studies, long-term epidemiological follow-up studies, and wide international genetic-epidemiological studies. He has published over 360 scientific articles in international journals, and these articles have almost 60 000 citations and a h-index of 106 (Google Scholar). He has supervised 24 doctoral theses and is a supervisor of another 13 doctoral students.