Research

Energy balance

Preoperative weight loss via low-calorie or very low-calorie diets reduces postoperative complications and surgical complexity in bariatric surgery patients.

If you are scheduled for bariatric surgery, follow your surgeon's preoperative diet instructions strictly. This typically involves eating 800-1200 calories a day for 2-4 weeks before the operation. This is not just about weight loss; it shrinks your liver, making the surgery safer and reducing the risk of complications.

GoodSupportsHIGH confidence
A preoperative low-calorie diet (LCD, 1000–1200 kcal/d) or very low-calorie diet (VLCD approx. 800 kcal/d) for 2-4 weeks is usually recommended in bariatric centres. This has been shown to reduce liver volume by 16–20 % and the surgeon’s perceived complexity of the procedure... preoperative weight loss was associated with reduction in postoperative complications (18.8 ± 10.6 vs. 21.4 ± 13.1 %, p = 0.02)
Anders Thorell et al. · World Journal of Surgery · 2016

Why this rating

Based on systematic reviews, multicentre RCTs, and large registry studies (Scandinavian Obesity Registry), though some evidence is from non-randomized studies.

Source

Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations

Anders Thorell et al. · World Journal of Surgery · 2016

DOI 10.1007/s00268-016-3492-3

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DOI resolved against Crossref · corpus check 2026-06-10

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