About Dr Kaleb Lourensz
Dr Kaleb Lourensz MBBS, PGDipSurgAnat, MSurg, FRACS, MIPDEd
Upper GI, Weight Loss and General Surgeon
Dr Kaleb Lourensz is a specialist general surgeon with subspecialty training in upper GI and weight loss (bariatric) surgery at The Alfred in Melbourne and at Oxford University Hospitals, UK. He consults and operates at The Avenue Hospital in Windsor and Calvary Holmesglen Private Hospital in Moorabbin. View consulting locations and parking.
Approach to Your Care
Surgery isn't the right answer for everyone. Dr Lourensz takes the time to listen, and to explain all of your options, including the ones that don't involve an operation. You should leave your appointment knowing what surgery would involve, the risks, what recovery looks like and what else you could do instead, and feeling that the decision is yours.
He posts short, evidence-based explainers on weight, reflux and surgery on Instagram at @uppergisurgeon.
A Little More About Me
I grew up in Melbourne before moving to country Victoria at the start of high school. My father worked as a rural GP anaesthetist in Benalla for 28 years, and I was drawn to medicine as a teenager. Since then, I've found it hard to imagine doing anything else.
My practical skills first developed while working on our family farm, and surgery felt like a natural fit. I enjoy the breadth of general surgery and the precision and attention to detail that upper gastrointestinal surgery demands. Working with cancer patients in the busy, internationally recognised upper GI unit at Oxford University Hospitals was a particular privilege. Researching ways to improve patients' quality of life after surgery, especially after oesophagectomy, has been one of the most rewarding parts of my career.
My patients have also taught me a great deal about obesity and the challenges of living with it. Listening to their experiences has deepened my understanding that obesity is a serious, complex condition that deserves comprehensive treatment, compassion and ongoing support. Through my training and clinical experience, I have developed the skills to offer both surgical and non-surgical care, tailoring treatment to each person's health, circumstances and goals.
I have a strong interest in preventive medicine and enjoy keeping active through HIIT, cycling and running, with a round of golf whenever I can fit one in. Our two children provide plenty of exercise of their own, and we love living in Melbourne's bayside community.
Training
Dr Lourensz studied medicine at Monash University and became a Fellow of the Royal Australasian College of Surgeons in 2020.
After general surgical training, he completed fellowship training with the Oesophago-gastric and Bariatric Unit at The Alfred, a highly regarded teaching hospital affiliated with Monash University.
He was then competitively selected for a prestigious international fellowship at Oxford University Hospitals, the teaching hospitals of the University of Oxford. During this 12-month fellowship, he gained extensive experience operating on oesophageal and stomach cancer, reflux and hiatus hernia, obesity, and complex benign upper GI conditions. On completion, he was awarded the Diploma of Membership of the International Postgraduate Deanery, Royal College of Surgeons of Edinburgh (MIPDEd).
He also holds a Master of Surgery from the University of Sydney and a Postgraduate Diploma in Surgical Anatomy from the University of Melbourne.
Areas of Focus
- Reflux and hiatus hernia surgery, including large and recurrent hernias
- Weight loss treatment, with or without surgery, including lap band management, removal and revision
- Oesophageal and stomach cancer, and its prevention
- Gastroscopy (upper endoscopy), including Barrett's oesophagus surveillance and assessment before and after weight loss surgery
Research
Dr Lourensz has recently submitted his PhD thesis through Monash University. His research looks at how the stomach behaves after oesophagectomy and weight loss surgery: how it empties, how it contracts, and how bypass limb length affects outcomes after one anastomosis gastric bypass. He used dynamic MRI scans, manometry and nuclear medicine scans to study patients in detail over time.
That work has shaped how he assesses and cares for patients before and after surgery.
He received an Australian Government Research Training Program Scholarship and an Aftershock Foundation grant for oesophageal cancer research.
Research Prizes
- Best Research Presentation, AANZGOSA/SUGSS Annual Scientific Meeting, 2024
- D.S. Rosengarten Prize for Best Research Presentation, 2024
- D.S. Rosengarten Prize for Best Research Presentation, 2021
Selected Publications
- Lourensz K, Wickremasinghe A, Bigwood S, Johari Y, Beech P, Hebbard G, Burton P, Brown WA. Peristalsis of the gastric conduit post-esophagectomy: is it relevant? Detailed conduit analysis using dynamic magnetic resonance imaging. Diseases of the Esophagus 2026;39(2):doag045. doi:10.1093/dote/doag045
- Leang YJ, Lourensz KR, Vanguardia MK, Hensman CS, Loh D, Chen R, Packiyanathan AJ, Kong JCH, Brown WA, Burton PR. Robotic intracorporeal anastomosis enhances technical precision while reducing surgeon cognitive load: a prospective multicentre study. Surgical Endoscopy 2026;40(9):7746-7756. doi:10.1007/s00464-026-13095-8
- Leang YJ, Bell SW, Lourensz KR, Vanguardia MK, Kong JCH, Burton PR, Brown WA. Assessing cognitive workload and performance in the operating room: challenges in applying NASA-TLX among experienced surgeons. ANZ Journal of Surgery 2026;96(7-8):2193-2202. doi:10.1111/ans.70589
- Brown WA, Leang Y, Lourensz KR. Is it just component separation that improves reoperation rates? JAMA Surgery 2025;160(1):18. doi:10.1001/jamasurg.2024.5068
- Lourensz K, Himantoko I, Shaw K, Laurie C, Becroft L, Forrest E, Nottle P, Fineberg D, Burton P, Brown W. Long-term outcomes of revisional malabsorptive bariatric surgery: do the benefits outweigh the risk? Obesity Surgery 2022;32(6):1822-1830. doi:10.1007/s11695-022-06019-7
- Lourensz K, Loh D, Burton P. Post-oesophagectomy chyle leak presenting as a pleuro-enteral lymphatic shunt via the gastric conduit. ANZ Journal of Surgery 2021;91(10):E652-E653. doi:10.1111/ans.16696
- Chittleborough TJ, Lourensz K, Elliott M, Thomas P, Franzi S. Outreach surgical consulting services in North East Victoria. Australian Journal of Rural Health 2013;21(6):325-328. doi:10.1111/ajr.12065
Selected Presentations
- Gravity-mediated emptying as a key mediator of gastric conduit emptying following oesophageal reconstruction. AANZGOSA/SUGSS Annual Scientific Meeting, 2024 (Best Research Presentation)
- Investigating key mediators in gastric conduit emptying. D.S. Rosengarten Prize, Best Research Presentation, 2024
- Gastric conduit peristalsis, anatomy and emptying: challenging our current assumptions. RACS 92nd Annual Scientific Congress, Christchurch, 2024
- Peristalsis of the gastric conduit post-oesophagectomy: does it exist, does it matter? Posters of Distinction oral presentation, ISDE World Congress, Edinburgh, 2024
- Peristalsis and anatomy of the gastric conduit following oesophageal reconstruction. Melbourne Upper Gastrointestinal Surgeons Meeting, 2024
- Quality of life and adverse gastrointestinal symptoms in post-oesophagectomy patients. AANZGOSA/ANZMOSS Annual Scientific Meeting, 2023
- The role of peristalsis in gastric conduit emptying. Main stage oral presentation, AANZGOSA Annual Scientific Meeting, 2022, and D.S. Rosengarten Presentation, 2022
- Long-term outcomes of revisional malabsorptive bariatric surgery. ANZMOSS Annual Scientific Meeting, Best of Free Papers, 2020; RACS Annual Scientific Congress, 2020; D.S. Rosengarten Presentation, 2021 (prize winner)
Qualifications and Memberships
MBBS (Monash), PGDipSurgAnat (Melbourne), MSurg (Sydney), FRACS, MIPDEd (RCSEd)
Recognised by the Conjoint Committee for the Recognition of Training in Gastrointestinal Endoscopy (CCRTGE) to perform gastroscopy. The committee is run jointly by GESA (the Gastroenterological Society of Australia), the Royal Australasian College of Surgeons and the Royal Australasian College of Physicians.
- Member, Australian and New Zealand Gastric and Oesophageal Surgery Association (AANZGOSA)
- Member, Australian and New Zealand Metabolic and Obesity Surgery Society (ANZMOSS)
- Member, International Society for Diseases of the Esophagus (ISDE)