Stewart is a licensed clinical psychologist who provides mental health treatment and conducts behavioral health research as Director of the Behavior Technology Laboratory. She was the lead scientist who developed one of the first computerized procedures for measuring body image called the Body Morph Assessment. Stewart also established the first treatment clinic at Pennington Biomedical Research Center, the Diabetes Clinic, after working with the Louisiana State UniversityBoard of Regents to expand Pennington's mission beyond prevention research to include disease treatment. Stewart has been recognized for her work including the Louisiana Legislative Women's Caucus Women of Excellence Award for Health & Medicine, the 2020 Baton Rouge Influential Women in Business distinction, and Louisiana State University's Esprit de Femme award. She has also presented a TEDx talk entitled, "The Body Revolution We Need: Function Over Form".