Lab Members

Our Staff

Section Chief, Obesity and Diabetes Clinical Research Section
Dr. Jonathan Krakoff is the section chief of the Obesity and Diabetes Clinical Research Section, Phoenix Epidemiology and Clinical Research Branch and a board-certified endocrinologist and internist. His research investigates the etiology of type 2 diabetes and obesity, primarily by focusing on issues that affect energy balance, energy expenditure, and energy intake.
Photo of Douglas Chang.
Dr. Douglas Chang is Medical Director of the Clinical Research Unit in the Obesity and Diabetes Clinical Research Section of NIDDK Phoenix.  Dr. Chang is board certified in both Internal Medicine and Obesity Medicine.  Current research interests include understanding determinants of energy intake and expenditure with a special emphasis on examining the interaction between hydration and obesity which is characterized by prolonged energy imbalance. Additional research examines the role of insulin and glucose regulation in metabolism and investigates novel biomarkers of type 2 diabetes.
Photo of Marci Gluck.
Director of Behavioral Sciences
Dr. Marci Gluck is Director of Behavioral Sciences in the Obesity and Diabetes Clinical Research section of the NIDDK. She is a trained clinical health psychologist, having completed her graduate training from the Albert Einstein College of Medicine from Yeshiva University, her predoctoral internship at Yale University School of Medicine, and her NIH postdoctoral fellowship at Columbia University College of Physicians and Surgeons. Dr. Gluck has over 20 years of experience conducting clinical studies in adults with obesity and disordered eating behaviors. Her research focuses on the integration of behavioral, neuropsychological and physiological mechanisms that influence appetitive behavior and body weight regulation.  In her spare time, Dr. Gluck enjoys hiking, spending time with her two dogs Ben & Jerry and complaining about the Arizona heat!
Photo of Susanne Votruba
Research Nutritionist
Dr. Votruba has a Ph.D. in Nutritional Sciences and is a Registered Dietitian. She is the only R.D./Ph.D. at NIDDK PECRB, and is responsible for the oversight of the metabolic kitchen and also functions as a PI on several studies. Her research interests include improving measurement of food intake and establishing determinants of weight loss and gain. Her broader research interests are in the metabolic determinants of obesity, obesity phenotypes, the measurement of food intake, the development of biomarkers of food intake, and the interaction of the microbiome with the physiology of metabolism.
Photo of Tomás Cabeza de Baca.
Staff Scientist
Tomás Cabeza de Baca, Ph.D., is a staff scientist for the Obesity and Diabetes Clinical Research Section in Phoenix, Arizona. He received his doctoral degree from the University of Arizona and completed his postdoctoral training at the University of California, San Francisco. His research interests include the examination of psychosocial, ecological, and physiological determinants of energy intake and expenditure and their underlying effects on cardiometabolic risk and physiological deterioration. In his spare time, Tommy enjoys shortening his telomeres with cheeseburgers and tequila.
Photo of Paolo Piaggi.
Staff Scientist
Paolo Piaggi, Ph.D. is interested in the physiological and genetic determinants of the energy balance equation (energy intake and expenditure) and the role these play in contributing to weight change and in predisposing individuals to obesity.
Photo of Emma Stinson.
Emma J. Stinson, M.P.H.
Emma J. Stinson, M.P.H. is a statistician for the Obesity and Diabetes Clinical Research Section in Phoenix, Arizona. She received her master’s degree in Biostatistics from Drexel University in March of 2020. Her research interests include the development and application of statistical methodology in the study of obesity and eating behaviors with an emphasis on the psychosocial and behavioral determinants of energy intake and energy expenditure.

Our Fellows

Photo of Cassie Mitchell.
Cassie M. Mitchell, Ph.D., R.D.
Post-doctoral Intramural Research Training Award Fellow
Cassie holds her Ph.D. in clinical physiology and metabolism from Virginia Tech and is a registered dietitian (R.D.). Cassie completed her supervised clinical hours to become an R.D. through Phoenix Indian Medical Center in 2019, and then joined the ODCRS in May 2019. She has a decade of experience collaborating and conducting research focused on nutrition, exercise and physical activity research in both clinical and community populations. In her spare time she enjoys experiencing nature with her rescue dogs and horses. 
Yigit Unlu, M.D.
Visiting Fellow
Yigit Unlu, M.D. is a visiting fellow for the Obesity and Diabetes Clinical Research Section in Phoenix, Arizona. He received his doctoral degree from Acibadem University School of Medicine in Istanbul, Turkey and practiced medicine in an E.R. for 10 months before joining NIDDK. His research interests include the effects of Gut Hormones on Substrate Oxidation, Energy expenditure, different aspects of diet induced thermogenesis and clinical application of these findings.
Photo of Coley Andersen.
Coley Andersen, B.S.
Post-Baccalaureate Intramural Research Training Award Fellow

Coley is a post-baccalaureate fellow in the Obesity and Diabetes Clinical Research Section of NIDDK Phoenix. She received her B.S. in Biochemistry from Arizona State University in 2017. During her undergraduate career she focused her extracurricular studies in global health, with a concentration in health disparities and socioeconomic determinants. During her time at NIDDK Phoenix she has continued to expand on her interests working closely with Dr. Gluck and Dr. Cabeza de Baca on research related to psychosocial, cognitive, and behavioral determinants related to eating behaviors and energy intake/expenditure. As a member of the Diné (Navajo) community, she enjoys sharing and educating others about the history and culture. She is especially passionate about working with underserved and vulnerable populations and has collaborated with colleagues via articles and presentations on how to ethically engage in research with Indigenous communities. In her spare time, she loves to hike and spend time with her cat, Oliver. After her fellowship Coley plans to attend medical school and hopes to combine her interests in community, research, medicine, and public health.

Photo of Jetaun Booker.
Jetaun Booker, B.S.
Post-Baccalaureate Intramural Research Training Award Fellow
Jetaun is a premedical post-baccalaureate fellow in Dr. Krakoff’s lab. She completed her B.S. at Xavier University of Louisiana in May 2020. At this moment, her primary focus in the lab is looking at food insecurity and its effects on metabolic processes. She enjoys hiking, meditating, and playing with her two dogs. She will be attending medical school in 2022 to become a doctor and spread awareness on the importance of mindfulness and eating right to maintain a healthy life.
Photo of Nicolas Guerithault.
Nicolas Guerithault, M.S.
Post-Baccalaureate Intramural Research Training Award Fellow
Nicolas is a post-baccalaureate fellow in the Obesity and Diabetes Clinical Research Section. He received a B.S. in Biochemistry in 2016 and a M.S. in Neuroscience in 2021 from Arizona State University and is interested in metabolic, cognitive, and psychological health. His masters research explored mindfulness interventions for adults with autism, as well as relationships between food insecurity and cognitive function. As an IRTA fellow, he is exploring a variety of factors that may contribute to disruptions in food intake and energy metabolism. Outside of research, Nicolas enjoys cycling, being outdoors and roasting coffee. After completing his IRTA fellowship, he will attend medical school.
Photo of Katherine Travis
Katherine Travis, B.S.
Post-Baccalaureate Intramural Research Training Award Fellow
Kate is a post-baccalaureate fellow with Dr. Jonathan Krakoff’s lab. Since Graduating from Fort Lewis College in Durango, CO in 2020, she has enjoyed being immersed within the clinical research of diabetes and obesity conducted at NIDDK. Kate’s primary project focuses on secular trend analyses that took place from 1985 – 2005 when measurements of spontaneous physical activity, 24-h energy expenditure, and metabolic fuel selection were taken within an indirect calorimetry metabolic chamber. She is also interested in studying tDCS brain stimulation, as a potential mediator for weight loss, and its long-term effects on cognitive task scores and caloric intake. Upon completion of her fellowship, she will pursue medical school.

Our Research Staff

Shellilene Bileen
Research Recruiter
Photo of Raymond Cortez.
Raymond R. Cortez III
Research Recruiter
Barbie J. Morales, R.N.
Clinical Research Nurse
Shannon Parrington
ODCRS Laboratory Supervisor
Photo of Terri Rodzevik.
Terri Rodzevik, D.N.P., F.N.P.-B.C., E.N.P.-C.
Supervisory Nurse Practitioner
Dacia Sorrell, R.N., B.S.N.
Clinical Research Nurse
Photo of Christian Young.
Christian Young
IT Specialist

Group Photos

Obesity week photo of ODCRS group.ODCRS group at the 2018 Obesity Week Conference in Nashville Tennessee.
Poster Presentation at The Obesity Week Conference.Statistician Emma Stinson presenting her research on Food Insecurity at The 2017 Obesity Week Conference in Washington, DC.