Kjetil is a senior researcher at the Norwegian Institute of Public Health and an associate professor at Western Norway University of Applied Sciences. He is a medical physicist with a PhD in tumour physiology and medical imaging, and is now working to promote evidence-based practice by supporting guideline processes, by giving lectures and by authoring systematic reviews. He has co-authored several systematic reviews about chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), e.g. a systematic review about case criteria and a traditional Cochrane review about the efficacy of exercise therapy for patients. He is also co-authoring an upcoming Cochrane review about exercise therapy based on individual patient data, a work that has given detailed insight into the existing evidence.