In 1999, Portenier completed medical school at the Medical University of South Carolina in Charleston, South Carolina. His general surgical training took place in Detroit, Michigan at Providence Hospital. During training he received the Charles G. Johnston Excellence in Research Award by the Detroit Surgical Society for excellence in research. In addition, he received the General Surgery Resident of the Year Award in 2003 and 2004, the Society of Lapro-endoscopic Surgeons Resident Achievement Award in 2004, as well as a medical student teaching award.
He spent the next year gaining extra experience in upper GI surgery including: liver, pancreas, and stomach surgery. This training was split with rotations at the Mayo Clinic in Rochester, Minnesota; Memorial Sloan-Kettering, New York City; and in Leeds, England.
In 2006, Portenier completed an Advanced Fellowship in Laparoscopic and Bariatric Surgery at Duke University and joined the Weight Loss Surgery Center's surgical staff. Portenier's clinical interests include minimally invasive and open approaches to advanced upper GI surgery, with a focus on weight loss surgery. The dramatic impact weight loss has on patients life has focused Portenier on surgical means of achieving lasting weight loss. He will perform Roux-en-Y gastric bypass, Lap Band, and revisional bariatric surgery.