Research

Energy balance

A 14-day very low-calorie diet (800 kcal/day) prior to laparoscopic gastric bypass reduces postoperative complication rates and perceived surgical difficulty, though it does not significantly alter operating time or short-term total weight loss.

Follow the prescribed 800-calorie liquid diet exactly for the two weeks before your surgery. This isn't just about weight loss; it shrinks your liver, making the surgery safer and easier for the surgeon, which significantly lowers your risk of infections and other complications after the operation. Do not skip the nutritional supplements provided with the diet.

GoodQualifiesHIGH confidence
Although weight reduction with a 14-day VLCD regimen before laparoscopic gastric bypass performed in high-volume centers seems to reduce the perceived difficulty of the procedure, only minor effects on operating time, intraoperative complications, and short-term weight loss could be expected. However, the finding of reduced postoperative complication rates suggests that such a regimen should be recommended before bariatric surgery.
Yves Van Nieuwenhove · Archives of Surgery · 2011

Why this rating

Randomized multicenter study with 298 patients, single-blind design, though underpowered for subgroup analysis of high BMI.

Source

Preoperative Very Low-Calorie Diet and Operative Outcome After Laparoscopic Gastric Bypass

Yves Van Nieuwenhove · Archives of Surgery · 2011

DOI 10.1001/archsurg.2011.273

rct · n=298Cited 238×
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DOI resolved against Crossref · corpus check 2026-06-10

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