Obesity is a major risk factor for perioperative morbidity, especially for patients undergoing complex incisional hernia repair. The feasibility and effectiveness of medical weight loss programs prior to complex abdominal wall reconstruction have not been well characterized. Here, we report our experience collaborating with a medical weight loss specialist utilizing a protein sparing modified fast in order to optimize weight loss prior to complex abdominal wall reconstruction. Morbidly obese patients (body mass index (BMI) > 35 kg/m(2)) evaluated by our medical weight loss specialist prior to complex ventral hernia repair were identified within our prospective database. Our primary outcome measure was the amount of weight lost prior to surgical intervention. Our secondary outcome measure was to determine the maintenance of weight loss during long-term follow-up after the surgical intervention. A total of 25 patients with a BMI > 35 kg/m(2) were evaluated by our medical weight loss specialist prior to undergoing a planned incisional hernia repair. The mean weight of the patients preoperatively was 128 kg ± 25 (range 96-205 kg) (mean ± standard deviation), and the mean BMI was 49 kg/m(2) ± 10 (range 36-85). After completion of the preoperative modified protein sparing fast, the mean preoperative weight loss of the group was 24 kg ± 21 (range 2-80 kg). The overall change in BMI for the group prior to surgery was 9 kg/m(2) ± 8 (0.6 to 33). The percentage of excess BMI loss and total BMI loss preoperatively was 37 % ± 23 (2 to 83) and 18 % ± 12 (1 to 43), respectively. Of the 24 patients that initially lost weight in the program preoperatively, 22 (88 %) successfully maintained their weight loss for the entire study period for an average of 18 months. Collaboration with a medical weight loss specialist and a surgeon with a structured approach using a modified protein sparing fast can successfully result in meaningful weight loss prior to complex abdominal wall reconstruction. The majority of patients in this study were able to maintain their weight loss during long-term follow-up. Utilization of a protein sparing modified fast in collaboration with a medical weight loss specialist is a valuable resource for guiding weight loss in patients with morbid obesity prior to elective complex surgical procedures.