Preoperative liver shrinking diet for bariatric surgery may impact wound healing: a randomized controlled trial

Background: In bariatric surgery, preoperative very low-calorie diets (VLCD) may better meet the technical demands of surgery by shrinking the liver. However, diets may affect tissue healing and influence bowel anastomosis in an as-yet-undefined manner. Objective: This randomized controlled trial aimed to examine the effect on collagen deposition in wounds in patients on a 4-week VLCD before laparoscopic gastric bypass. Setting: University hospital. Methods: The trial was undertaken in patients undergoing laparoscopic Roux-en-Y gastric bypass, with a control group (n = 10) on normal diet and an intervention group (n = 10) on VLCD (800 kcal) for 4 weeks. The primary outcome measured was expression of collagen I and III in skin wounds, with biopsies taken before and after the diet and 7 days postoperatively as a surrogate of anastomotic healing. Secondary outcome measures included liver volume and fibrosis score, body composition, operating time, blood loss, hospital stay, and complications. Results: Patients in both groups were similar in age, sex, body mass index (53.4 versus 52.8 kg/m ² ), co-morbidities, liver volume, and body composition. Expression of mature collagen type I was significantly decreased in diet patients compared with controls after 4 weeks of diet and 7 days after surgery. This was significant decrease in liver volume (23% versus 2%, P =.03) but no difference in operating times (129 versus 139 min, P =.16), blood loss, length of stay, or incidence of complications. Conclusions: Preoperative diets shrink liver volume and decrease expression of mature collagen in wounds after surgery. Whether the latter has a detrimental effect on clinical outcomes requires further evaluation.