Professor Karelis is interested, among other things, in the metabolic complications (hypertension, dyslipidemia, insulin resistance) associated with obesity and type 2 diabetes. More specifically, he characterizes two subtypes of obesity: young individuals living with metabolic problems associated with obesity but with a normal weight (MONW for Metabolically Healthy But Normal Weight) and obese but metabolically healthy individuals (MHO for Metabolically Healthy But Obese). Professor Karelis is also studying the effects of different types of physical training on metabolic complications in different populations.