Background Elective surgery in obese adults carries a higher risk of post‐operative infection and prolonged hospital stays, and surgeons may postpone surgery for patients with obesity until they lose weight. The present study aimed to determine the efficacy of a dietitian‐led very low calorie diet (VLCD)‐based model of care with respect to achieving weight loss for obese patients prior to surgery. Methods This mixed‐methods study included a medical chart audit of patients referred to a VLCD‐based model over 23 months, as well as a survey of recently treated patients and surgeons who utilised the model. Preoperative weight loss targets were set by surgeons, and the dietitian prescribed individualised VLCD‐based treatment. Efficacy was determined as weight loss considered sufficient for surgery, clinical safety of VLCD‐based treatment, feasibility, and stakeholder value. Pre/post‐intervention differences in clinical measures were explored by paired t‐test or Wilcoxon tests as appropriate. Results Data on seventy‐eight eligible patients [mean (SD) 45 (13) years, 90% female, body mass index 44.3 (6.2) kg m–2] demonstrated significant mean (SD) weight loss of 7.4% (5.3%) body weight (P < 0.05). Most patients (70%, n = 50/71) achieved sufficient weight loss to proceed to surgery. Fifty‐six per cent of patients reported mild side effects (n = 43/77) and none led to treatment cessation. Surgeons reported VLCD‐based treatment made operations easier (83%, n = 10/12) and shorter (75%, n = 9/12) and all recommended the model of care. All surveyed patients (n = 24) reported satisfaction with their VLCD‐based model experience. Conclusions A dietitian‐led VLCD‐based model achieved sufficient weight loss to facilitate elective surgery for most patients. The approach was feasible, highly valued by patients and surgeons, and resulted in perceived surgical benefits.

This systematic review summarises the literature regarding the impact of preoperative dietary interventions on non-bariatric surgery outcomes for patients with excess weight/obesity, a known risk factor for poor surgical outcomes. Four electronic databases were searched for non-bariatric surgery studies that evaluated the surgical outcomes of a preoperative diet that focused on weight/fat loss or improvement of liver steatosis. Meta-analysis was unfeasible due to the extreme heterogeneity of variables. Fourteen studies, including five randomised controlled trials, were selected. Laparoscopic cholecystectomy, hernia repair, and liver resection were most studied. Diet-induced weight loss ranged from 1.4 kg to 25 kg. Preoperative very low calorie diet (≤800 kcal) or low calorie diet (≤900 kcal) for one to three weeks resulted in: reduction in blood loss for two liver resection and one gastrectomy study (−27 to −411 mL, p < 0.05), and for laparoscopic cholecystectomy, reduction of six minutes in operating time (p < 0.05) and reduced difficulty of aspects of procedure (p < 0.05). There was no difference in length of stay (n = 7 studies). Preoperative ≤ 900 kcal diets for one to three weeks could improve surgical outcomes for laparoscopic cholecystectomy, liver resection, and gastrectomy. Multiple randomised controlled trials with common surgical outcomes are required to establish impact on other surgeries.

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