A key focus of his research addresses the causes of lifestyle diseases as well as their primary prevention and the scientific evaluation of intervention measures. Further research interests lie in the area of the aetiology of cancer with focus on environmental factors and occupational exposures and the use of secondary data for epidemiological research. He initiated the largest Europe-wide intervention study on overweight, obesity and other disorders in children conditioned by nutrition, lifestyle and social factors (www.idefics.eu; 2006-2012) and coordinated the subsequent prospective cohort study on lifestyle, diet and exercise in children, adolescents and their parents - the I.Family study (www.ifamilystudy.eu; 2012-2017).