My research program established links between molecular clocks and metabolism that have been at the forefront of studies of circadian medicine. We made the seminal discovery that disruption of the core molecular clock causes constant hunger, disrupted sleep, defective insulin secretion, diabetes and obesity, establishing a role for clock genes in interorgan physiology and health. I also showed that obesogenic diet causes reciprocal disruption of the circadian clock through epigenetic modification of the core clock transcription factor PERIOD2 and reprogramming of rhythmic circadian cycles in brain and metabolic cells. Our recent studies reveal that the time when an animal eats controls adipose thermogenesis thereby explaining how the body clock controls energy balance. With highly cited publications in Cell Metabolism, Nature, and Science, and by forging collaborations bridging epidemiology and pathophysiology, my work has united communities of circadian biology, neuroscience, biochemistry, and metabolic physiology. As an academic leader in medicine, I have been active in the Endocrine Society, serving on the scientific planning committee, and the American Diabetes Association. At the national level, I served as the Chair of the NIH Integrated Physiology of Obesity and Diabetes study section, and I am an editorial board member of the Journal of Clinical Investigation, Genes and Development, Cell Metabolism, and Trends in Endocrinology and Metabolism. I am a member of AOA, the Association of American Physicians and the 2023 recipient of the Greep Award of the Endocrine Society for Outstanding Basic Science Research and the 2023 Award for Outstanding Scientific Achievement from the Sleep Research Society. I was elected to the National Academy of Medicine in 2025.