Very low energy diets before nonbariatric surgery: A systematic review and meta-analysis

Published:October 20, 2022DOI:



      Very low energy diets serve as an intensive approach to weight loss in a short period of time. Although the preoperative use of very low energy diets to optimize patients with obesity before bariatric surgery is well established, the evidence for very low energy diets before other types of surgery remains unclear. The aim of this review was to determine the impact of preoperative very low energy diets on perioperative outcomes in nonbariatric surgery.


      Medline, EMBASE, CENTRAL, and PubMed were systematically searched from inception through to July 2021. Articles were included if they evaluated very low energy diets use before any type of nonbariatric surgery. The primary outcome was postoperative morbidity. Secondary outcomes included compliance, safety, and preoperative weight loss. A pairwise meta-analyses using inverse variance random effects was performed.


      From 792 citations, 13 studies with 395 patients (mean age: 56.5 years, 55.8% female) receiving very low energy diets preoperatively in preparation for nonbariatric surgery were included. Mean duration of preoperative very low energy diets was 6.6 weeks (range, 0.42–17 weeks). Target daily caloric intake ranged from 450 kcal to 1,400 kcal. Compliance with very low energy diets ranged from 94% to 100%. The mean preoperative weight loss ranged from 3.2 kg to 19.2 kg. There were no significant differences in postoperative morbidity (odds ratio, 1.10; 95% confidence interval, 0.64–1.91; P = .72), operative time (standard mean difference –0.35; 95% confidence interval, 1.13–0.43, P = .38), or postoperative length of stay (standard mean difference 0.40, 95% confidence interval –0.11–0.91, P = .12) with very low energy diets.


      Although the currently available evidence is heterogenous, preoperative very low energy diets are safe, well tolerated, and effectively induce preoperative weight loss in patients undergoing nonbariatric surgery for both benign and malignant disease. Further prospective studies are warranted.
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