Paul MacLean, PhD
Director, NORC

Dr. Paul MacLean Ph.D. is a tenured Professor at the University of Colorado School of Medicine with 25years of experience studying obesity and its metabolic complications. He has specific interests in the biological drivers of weight regain after weight loss, exercise as a strategy for weight loss maintenance, and understanding how obesity affects key aspects of women’s health. Dr. MacLean's research in women’s health has included studies of mammary gland development and its function during lactation, perinatal metabolic programming, the menopausal transition, and the risk for breast cancer. He is dedicated to building and supporting the broader research and educational enterprise on the CU Anschutz Medical Campus through the Colorado Nutrition Obesity Research Center, the Colorado Clinical Translational Science Institute, and the University of Colorado Cancer Center. Over the past 17years at the University of Colorado, Dr. MacLean has leveraged their resources to develop the next generation of scientists who will advance the treatment of obesity and its complications.

Molecular Core
Dan Bessesen, MD
Associate Director, NORC

Dr. Daniel Bessesen M.D. is a professor of medicine of endocrinology, metabolism, and diabetes at The University of Colorado. Dr. Bessesen received his MD with honors from The University of Colorado. He completed residency and fellowship training at The University of Colorado and has been on the faculty since 1991. He is the director of the obesity medicine fellowship program and  the associate director of fellowship training in endocrinology. Dr. Bessesen is the associate director of the NIH-funded Nutrition Obesity Research Center and oversees the pilot and feasibility program. He is currently the Director of the Anschutz Health and Wellness Center on the campus of the University of Colorado, School of Medicine, an 80,000 sq. foot building with a fitness facility, a metabolic kitchen, a demonstration kitchen and a clinic. The center provides support for research, education and clinical programs in nutrition, physical activity and mental wellbeing. Dr. Bessesen has been a member of The Obesity Society since he was a post-doctoral fellow and is currently the president elect of TOS. Dr. Bessesen has published more than 90 scientific articles and book chapters and is the coauthor of three books, including Treatment of the Obese Patient published in 2014.

Administrative Core
Marc Cornier, MD
Director, Clinical Intervention and Translation Core

Dr. Marc Cornier M.D. has been on faculty at the University of Colorado with the Division of Endocrinology, Metabolism, and Diabetes since 2001, where he is currently a Professor of Medicine and Associate Division Head. Prior to that, he received his undergraduate education at Vanderbilt University in Biomedical Engineering. He then attended the Medical College of Georgia where he received his medical degree. He went onto do his medical residency at Georgetown University Medical Center and followed this with a fellowship in endocrinology at the University of Colorado Health Sciences Center. Dr. Cornier is currently the Director of the NORC Clinical Intervention and Translation Core. He also serves as the associate director of the CU Anschutz Health and Wellness Center, Medical Director of the My New Weigh meal-replacement weight loss program at the CU Anschutz Health and Wellness Center, and Director of the LDL Apheresis Program at the University of Colorado Hospital. He also runs a lipid and a diabetes clinic at the University of Colorado Hospital. Dr. Cornier is an active clinical and translational investigator with a primary research interest in obesity and nutrition. Specifically in understanding the complex regulation of food intake and body weight and metabolism. He has also been involved in clinical trials with lipid-lowering medications. Dr.Cornier has been a very active volunteer in important health-related associations, including the Obesity Society, Endocrine Society, American Diabetes Association, and American Heart Association.

Clinical Intervention and Translation Core
Wendy Kohrt, PhD
Director, Energy Balance Assessment Core

Dr. Wendy Kohrt Ph.D. is a Professor of Medicine in the Division of Geriatric Medicine at the University of Colorado Anschutz Medical Campus and the Nancy Anschutz Endowed Chair In Women's Health Research. She is the Director of Research for Geriatric Medicine and the Director of the IMAGE research group (Investigations in Metabolism, Aging, Gender, and Exercise). Dr. Kohrt is the Director of the Energy Balance Core Laboratory for the NIH-supported Nutrition and Obesity Research Center and is the Chair of the Scientific Advisory and Review Committee for the Adult Clinical and Translational Research Center. She served on the Federal Advisory Committee that prepared the evidence report for the first Physical Activity Guidelines for Americans, which were launched by the Department of Health and Human Services in October 2008. She is an invited member of the Isis Network on Musculoskeletal Health through the Society for Women’s Health Research. Dr. Kohrt is currently serving as co-chair of the Steering Committee assembled by the National Research Council to conduct the Decadal Survey on Biological and Physical Sciences in Space, which will recommend research to support space exploration in the 2010 to 2020 decade. Dr. Kohrt has been recognized as a Distinguished Alumnus by the University of Wisconsin Stevens Point and received a Citation Award from the American College of Sports Medicine.Dr. Kohrt has been continuously funded by the NIH as a Principal Investigator for more than two decades and has more than 140 original and solicited research publications. She is currently the Principal Investigator for two NIH R01 research awards and a Co-investigator for six other NIH awards. She has mentored or co-mentored 24 Ph.D.-trained and 14 M.D.-trained investigators, the majority of whom have established independent research careers.

Energy Balance Assessment Core
Bryan Bergman, PhD
Director, Molecular and Cellular Analytical Core

Dr. Bergman is a Professor in the Division of Endocrinology, Diabetes, and Metabolism at the University of Colorado Anschutz Medical Campus. Dr. Bergman’s research investigates the relationship between muscle lipids and insulin sensitivity, and he has been continuously funded by the NIH since 2005. His laboratory focuses on two main research themes. One theme seeks to understand the relationship between skeletal muscle subcellular lipid localization and insulin resistance in humans. Specifically, his lab is investigating how the intracellular location, molecular species, and isomers of diacylglycerol and sphingolipids promote insulin resistance in humans. The current study is investigating these changes after insulin sensitizing lifestyle interventions and is funded by R01DK111559.  The second research emphasis aims to elucidate how intermuscular adipose tissue impacts skeletal muscle insulin sensitivity, muscle strength, and size in humans. This study combines muscle biopsy visits with elective surgeries to obtain intermuscular, subcutaneous, and visceral adipose tissue biopsies and is funded by R01DK118149.  Dr. Bergman’s laboratory also pursues mechanistic relationships between inter- and intra-muscular lipids and insulin sensitivity using primary muscle cell culture. This model is unique as the phenotype of donor is maintained in culture.  They are using this model to determine mechanisms underlying the relationship between localized muscle lipids and insulin sensitivity, and how the secretome of intermuscular adipose tissue promotes insulin resistance.  The overall goal of Dr. Bergman’s research is to uncover novel therapeutic targets to increase muscle insulin sensitivity, a need not bet by currently therapies, to help prevent and treat pre-diabetes and type 2 diabetes.

Molecular and Cellular Analytical Core
Edward Melanson, PhD
Director, Enrichment Program

Dr. Edward Melanson Ph.D., is a Professor of Medicine, Division of Endocrinology, Metabolism, and diabetes, with a secondary appointment in the Division of Geriatrics. He is also an Assistant Director of the Energy Balance Core Lab. In this capacity, he oversees the operation of the whole-room calorimeter, located on the Clinical and Translational Research Center (CTRC). Dr. Melanson’s interests are on the effects of diet, exercise, and obesity on substrate metabolism and energy expenditure. The primary areas of research in Dr. Melanson’s lab are:

Developing new methods for assessing energy expenditure and physical activity in free-living humans
These studies are focused on advancing analytical approaches of accelerometer data to measure physical activity. Dr. Melanson’s laboratory also has the capacity to measure free-living energy expenditure using the doubly labeled water method and is advancing new approaches to measuring isotope enrichments in biological samples using laser absorption spectroscopy.
Studying the effects of menopause impacts bioenergetics and metabolism
The menopausal transition is associated with an increase and redistribution of body fat from lower body to upper body depots. Dr. Melanson is involved in research to understand the mechanisms by which this occurs. In studies performed in collaboration with Wendy Kohrt, Ph.D., Professor of Geriatric Medicine, we have shown that suppression of ovarian function reduces energy expenditure and physical activity and that these changes are attenuated with the replacement of estrogen. Dr. Melanson’s lab is currently studying how estrogen status impact brown fat activity. These studies involve novel approaches to measure brown fat activity using two radioactive tracers combined with dynamic PET/CT scanning.
Understanding how lifestyle interventions, particularly adoption of regular exercise and alterations in sleep, impact physical activity, sedentary behavior, and health outcomes
In collaboration with Kenneth Wright, Ph.D., Professor, Department of Integrative Physiology at the University of Colorado, Boulder, Dr. Melanson has performed several studies to determine the impact of sleep restriction on energy expenditure and substrate metabolism. Current studies in our lab are focusing on understanding the impact of different intensities and timing of exercise on glycemic control, non-exercise physical activity, and sleep in older adults. Dr. Melanson is also a co-investigator on the Colorado Clinical Center for the study of Molecular Transducers of Physical Activity Consortium (MoTrPAC) –Colorado Clinical Center. This NIH Common Fund initiative will develop a national resource of molecular responses to physical activity that will advance the understanding of the mechanisms by which physical activity improves health.

Enrichment Core
Richard Johnson, MD
Executive Committee

Dr. Johnson has performed medical research since the early 1980s and have been funded by the NIH since 1987. Most of his research has focused on the pathogenesis of kidney diseases, but during the last 12 years his studies have also included studies of the pathogenesis of primary hypertension, insulin resistance and diabetes, diabetic nephropathy, and obesity. Much of Dr. Johnson's work has involved a combination of cell culture and animal models with a strong translational component, but has also been involved in a number of clinical trials and epidemiology based studies. One of his special interests has been on the role of uric acid and of sugar (especially the component, fructose) in obesity and diabetes. As such, Dr. Johnson has greatly enjoyed his collaborations with other NORC investigators and also with the use of the NORC core facilities.  

Nancy F. Krebs, MD, MS
Executive Committee

Professor of Pediatrics, Head, Section of Nutrition, Associate Vice Chair, Academic Affairs, Dept of Pediatrics

My primary research interests in maternal and infant nutrition extend from detailed metabolic studies of zinc and iron across the life cycle, to large scale RCT of supplements and/or food-based interventions. The focus of these studies has been to define dietary micronutrient requirements and to characterize homeostasis, including metabolic regulation and adaptation to different physiologic states, in normal infants, pregnant & lactating women.  I have extensive experience directing intervention trials to monitor and evaluate growth and development in infants and toddlers. Currently I direct the ongoing analyses of the preconception maternal nutrition intervention trial (“Women First”) in 4 low resource countries. Outcomes from birth through 24 months include those of public health interest (birth anthropometry, infant/child stunting rates) plus extensive maternal and infant phenotyping, e.g. metabolomics, microbiome and epigenetic data.  My research laboratory extensively employs mass spectrometry (ICP-MS) to measure stable isotope tracers and multi-element mineral analyses in biological and food samples, and we conduct multiple ELISA’s for biomarkers of nutritional status.

In recent years our emphasis on studies in Denver has focused on risk factors in the first 1000 days, including effects of maternal obesity on milk production, bioactive compounds in human milk and the impact on offspring risk for excessive weight gain. We have also conducted interventions modifying the composition of complementary foods and evaluated the effects on growth, adiposity, microbiome and metabolomics.  Current studies include a trial of different iron intakes in healthy formula fed newborns; outcomes include effects on the enteric microbiome, systemic and intestinal inflammation, innate immunity and metabolomics.  


James McManaman, PhD
Executive Committee

Dr. McManaman is a tenured Professor of Reproductive Sciences and Director of the Integrated Physiology Graduate Program at the University of Colorado School of Medicine.  Dr. McManaman assists the CU NORC in connecting to our graduate students who have interests in nutrition, obesity, and metabolic diseases.

The bulk of Dr. McManaman's research efforts for the past 20 years have focused on the molecular mechanisms regulating lipid storage, trafficking, metabolism and secretion and the effects of their disruption on metabolic disease risk.  His laboratory has spent considerable effort defining the physiological, biochemical and molecular processes regulating triglyceride production and secretion and how these processes affect obesity and fatty liver disease risk in adult and neonatal mice, and adult mouse reproductive functions.  They have developed diet-induced obesity and mouse transgenic and knockout animal models and the physiological tools to study these processes.  These efforts have resulted in publications demonstrating the physiological importance of members of the perilipin family of lipid droplet scaffolding proteins in regulating mammary gland development, adipose function and thermogenesis, diet-induced obesity, and alcoholic and non-alcoholic fatty liver disease.  Significantly, their obesity research efforts led to the discovery alterations in host lipid storage functions profoundly influence gut microbial physiological responses to dietary fat consumption.