Stephen Previs received his PhD in Nutritional Biochemistry from Case Western Reserved University under the direction of Dr Henri Brunengraber, where he applied stable isotope tracer methods to study glycerol metabolism and gluconeogenesis. He then took a post-doctoral position at Yale University under the direction of Dr Gerald Shulman, during that period he combined the use of glucose-insulin clamps and stable isotope tracer methods for quantifying metabolic flux in novel mouse models of insulin resistance. He returned to Case Western for a fellowship under Dr Bernard Landau and was hired as a member of the faculty. His research interests were centered on understanding how the quantity and quality of dietary macronutrients influenced energy balance and the partitioning of carbon between fat and protein; those studies capitalized on his experience in the area of isotope tracers and mass spectrometry. Steve joined MRL in May 2009 after leaving his position as Associate Professor of Nutrition and Medicine. He has continued to use his background in metabolic disease in order to devise/implement methods for tracking the kinetics of endogenous molecules in vivo, the goal being to elucidate mechanism of drug action and/or identify biomarkers.