Altwaijri studied Community Health at King Saud University in Riyadh, receiving her B.Sc. in 1992. After marrying, she and her husband moved to the United States to attend graduate school. Altwaijri studied with Johanna Dwyer, director of the Frances Stern Nutrition Center at Tufts University's Friedman School of Nutrition Science and Policy. She received her M.Sc. from Tufts University in 1996 and her Ph.D in 2002. Her parents strongly encouraged her to have a professional career that would enable her to be financially independent.