She holds a joint appointment in the Department of Epidemiology at The Johns Hopkins Bloomberg School of Public Health. She obtained her MD from UMDNJ–Robert Wood Johnson Medical School and did her residency in Internal Medicine at Dartmouth-Hitchcock Medical Center after which she completed a fellowship in General Internal Medicine at Johns Hopkins and subsequently joined the faculty there in 2000. Clark's research focuses on the epidemiology and treatment of obesity and obesity-related consequences, including diabetes and nonalcoholic fatty liver disease. She is involved in several large, NIH-funded, multicenter, randomized clinical trials of lifestyle interventions to treat obesity and prevent its consequences.