Dan Bessesen, MD

Dr. Daniel Bessesen M.D. is a professor of medicine of endocrinology, metabolism, and diabetes at The University of Colorado, the director of fellowship training in endocrinology and the director of the Clinical Intervention and Translation Core of the NIH-funded Nutrition Obesity Research Center. 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. Dr. Bessesen, who conducts studies in dietary fat metabolism, appetite and the clinical problem of obesity, 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.

Adam Tsai, MD, MSCE, FACP
Associate Director

Physician, Kaiser Permanente Internal Medicine & Weight Management; Associate Professor, University of Colorado School of Medicine

Dr. Tsai is the medical lead for the weight management department at Kaiser Permanente. He is also the course director for the board review course in obesity medicine that is offered each year at Obesity Week. He serves as a consultant for Kaiser’s Care Management Institute, advising on national weight management guidelines and policies. He has over 70 publications in peer-reviewed medical journals, including the “In The Clinic” series in Annals of Internal Medicine on obesity.


David Saxon, MD, MSc

Assistant Professor of Medicine; Division of Endocrinology, Diabetes, and Metabolism; University of Colorado Hospital; Rocky Mountain VA Regional Medical Center

Dr. Saxon works clinically at the both the University and VA Hospitals and provides outpatient weight management care at both locations. He co-founded a pharmacotherapy-based weight loss clinic at the VA, which has proven to be very popular amongst Veterans. He is trained in health services research and his current research focuses on the use of weight loss medications throughout the VA system. 

Elizabeth Thomas, MD

Assistant Professor, Division of Endocrinology, Metabolism and Diabetes

My overall research goals are to investigate the effects of weight loss interventions on components of energy balance, and to ultimately translate this information into effective interventions for patients with obesity and related metabolic complications. Currently, I am interested in the circadian timing of energy intake and its role in the regulation of body weight. I am also interested in the individual variability in response to weight loss interventions (lifestyle and pharmacological) and finding predictors of response to weight loss interventions in order to provide more personalized recommendations to patients pursuing weight loss.

Jacinda Nicklas, MD, MPH, MA

Jacinda Nicklas, MD, MPH, MA is an Associate Professor at the University of Colorado School of Medicine. She received her MD from Harvard Medical School and completed her residency in internal medicine and primary care at Brigham and Women's Hospital in Boston, Massachusetts. She received her MPH from the Harvard School of Public Health and completed her clinical research fellowship in Integrative Medicine and General Medicine at Harvard Medical School. Dr. Nicklas completed the NIH-funded Building Interdisciplinary Research Careers in Women’s Health (BIRCWH) scholarship, and currently has a K23 career development award funded by the NIH National Heart Lung and Blood Institute. Her current research focuses on lifestyle interventions for postpartum women at elevated cardiometabolic risk using websites and apps. She is boarded in Internal Medicine and a diplomate in Obesity medicine and practices both primary care and obesity medicine.

Thomas Inge, MD, PhD

Professor of Surgery and Pediatrics; Associate Surgeon-in-Chief; Akers Endowed Chair and Director of Pediatric Surgery; Director, Adolescent Bariatric Surgery; Children's Hospital Colorado and University of Colorado, Denver

Dr. Thomas Inge, the leading surgeon in the U.S. for the surgical treatment of adolescent obesity. Dr. Inge leads the multicenter Teen-Longitudinal Assessment of Bariatric Surgery consortium, the largest and longest-term prospective study of surgical treatment of adolescent obesity.


Megan Kelsey, MD, MS

Associate Professor of Pediatric Endocrinology | Director of Lifestyle Medicine Endocrinology and Medical Director of Metabolic and Bariatric Surgery

Children’s Hospital Colorado | University of Colorado School of MedicineDr. Megan Kelsey is currently an Associate Professor in Pediatric Endocrinology at Children’s Hospital Colorado, where she serves as the Director of Lifestyle Medicine Endocrinology and Medical Director of the Adolescent Bariatric Surgery Center. Her research broadly focuses on improving prevention and treatment of type 2 diabetes in youth. Specifically, she is interested in the impact of metabolic and hormonal changes during puberty on risk for diabetes in obese youth and in sex differences in youth onset type 2 diabetes risk.

Shelby Sullivan, MD
Endoscopic Therapy

Dr. Sullivan is an Associate Professor of Medicine at the University Of Colorado School Of Medicine and is the director of the Gastroenterology Metabolic and Bariatric Program.  She graduated with a degree in Nutrition from the University of Wisconsin Madison where she studied the effect of caloric restriction on intracellular insulin signaling in a primate model.  She matriculated to Washington University School of Medicine for medical school and stayed through residency and fellowship to continue doing research in obesity and metabolism.  She joined the faculty at Washington University in 2004 and moved to the University of Colorado School of Medicine in 2016.

She has held both KL2 and K23 funding investigating the metabolic effects of exercise on nonalcoholic fatty liver disease and an isocaloric diet high in high-fructose corn syrup in patients with obesity and nonalcoholic fatty liver disease using in vivo metabolic techniques including hyperinsulinemic euglycemic clamps and hepatic lipoprotein tracer studies.  In addition, she has been involved a site primary investigator or sub-investigator on eight multi-center industry sponsored trials, one pilot study, and several post-market approval studies of endoscopic bariatric therapies for weight loss. 

Dr. Sullivan developed the first endoscopic bariatric therapy program at Washington University School of Medicine and was recruited to The University of Colorado school of Medicine to establish the Gastroenterology Metabolic and Bariatric Program.  She serves as the current chair of the board for the Association for Bariatric Endoscopy, is a counselor for the Obesity Metabolism and Nutrition Section of the AGA institute, and is the recent past chair of the Bariatric Surgery Section of The Obesity Society.

Nancy F. Krebs, MD, MS

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

Dr Krebs currently collaborates on several studies examining the fetal and early post-natal origins of childhood obesity, including investigations into the effects of maternal metabolic health on human milk production and nutrient and hormonal composition.  Trials during the complementary feeding period in older infants have demonstrated differential effects of dietary protein source on infant growth, body composition, and microbiome.

Victoria Catenacci, MD

Dr. Catenacci is an Associate Professor of Medicine at the University of Colorado Denver School of Medicine. Her specialties include: Internal Medicine, Board Certification (2001), Internal Medicine – Endocrinology, Diabetes, and Metabolism, Board Certification (2007). She completed her Undergraduate degree with a BS from the University of Notre Dame (IN) (1994) and completed medical school from Yale University School of Medicine (1998). She further completed her internship at Yale-New Haven Medical Center Program (1999) and Residency Program: Yale-New Haven Medical Center Program, Internal Medicine (2001) Yale-New Haven Medical Center Program, Chief Resident, Internal Medicine (2002). Dr. Catenacci’s clinical interests include: Diabetes, General Endocrinology, Physical Activity and Weight Loss/Maintenance​.