The fields of study he is best known for:
Internal medicine
Cancer
Disease
Internal medicine, Relative risk, Risk factor, Body mass index and Epidemiology are his primary areas of study. His Internal medicine research incorporates elements of Endocrinology, Vitamin E and Population study. The Relative risk study combines topics in areas such as Diabetes mellitus, Type 2 diabetes, Cancer and Cohort study.

His study in Risk factor is interdisciplinary in nature, drawing from both Pediatrics, Depression and Low back pain. The various areas that Paul Knekt examines in his Body mass index study include Socioeconomic status, Obesity, Blood pressure and Medical record. His biological study spans a wide range of topics, including Health survey, Gerontology, Overweight, Public health and Physical therapy.