Phillipp Hartmann, MD, MAS, DABOM, is a physician–scientist and Assistant Professor of Pediatrics (Gastroenterology) at the University of California San Diego and an attending pediatric gastroenterologist at Rady Children's Hospital–San Diego. His clinical practice centers on metabolic dysfunction–associated steatotic liver disease and steatohepatitis (MASLD/MASH), formerly known as NAFLD/NASH, and the care of children and adolescents with obesity. Dr. Hartmann's research investigates how the intestinal microbiome and related host–microbe pathways shape liver diseases, with his work spanning bacterial, fungal, and viral communities, bile acid signaling, and mucosal immunity. His overarching goal is to develop better, more individualized treatments to cure MASLD/MASH and related liver disorders. Trained in Germany and the United States, Dr. Hartmann earned his MD from the University of Regensburg, completed his pediatric residency and pediatric gastroenterology fellowship at UC San Diego, and obtained a Master of Advanced Studies in Clinical Research at UC San Diego. He is board-certified in General Pediatrics, Pediatric Gastroenterology, and Obesity Medicine. His work has been recognized with multiple awards and grants from the National Institutes of Health and leading foundations, including the NIH Pediatric Scientist Development Program, a KL2 (ACTRI) award, a current K12 career development award, and the AASLD Foundation Pinnacle Research Award in Liver Diseases. He is a full member of the San Diego Digestive Diseases Research Center and has served as an ad hoc member of several grant review sections. Within professional societies, he co-chairs the NASPGHAN MASLD and Obesity Special Interest Group and serves on the NASPGHAN Hepatology Committee. He has authored more than 50 peer-reviewed publications, including studies on global adolescent MASLD prevalence and the epidemiology and metabolic burden of extremely severe pediatric obesity, alongside mechanistic and translational work on bile acid signaling and the gut mycobiome in liver disease. His recent and ongoing projects emphasize pediatric MASLD natural history, precision biomarker development, and therapeutic pathways relevant to anti-obesity and liver-directed treatments. Outside the clinic and lab, Dr. Hartmann is an avid soccer player and an aspiring surfer.