Preoperative Weight Loss via Very Low Caloric Diet (VLCD) and Its Effect on Outcomes After Bariatric Surgery

Introduction: The effect of preoperative weight loss via very low caloric diet (VLCD) on long-term weight loss post-bariatric surgery (BS) is conflicting. We analysed its impact on weight loss and other outcomes post-BS.

Methods: Patients (n = 306) who underwent sleeve gastrectomy or gastric bypass from 2008 to 2018 were studied. VLCD was prescribed for 14 days preoperatively. Patients were followed up for 5 years. Postoperative weight loss was compared in patients with preoperative weight gain or weight loss < 5% (WL < 5%), and weight loss ≥ 5% (WL ≥ 5%). Preoperative WL compared weight before and after VLCD; postoperative WL compared post-VLCD weight and follow-up weight. Total weight loss (TWL) encompassed pre- and postoperative WL.

Results: WL was < 5% in 87.3% and ≥ 5% in 12.7%. There was no significant difference in complication rate, duration of surgery or length of stay, regardless of surgical type. Patients with WL < 5% lost more weight postoperatively compared with WL ≥ 5% for up to 60 months (%postoperative WL at 1 month: WL < 5% = 13.7%, WL ≥ 5% = 10%, p = <0.001; 60 months: WL < 5% = 30.6%, WL ≥ 5% = 23.9%, p = 0.041). However, when TWL and percentage of excess body mass index loss (%EBMIL) were measured, there was no difference beyond 6 months. A predictive multivariable model for 1-year %EBMIL was formed. Significant variables included pre-VLCD BMI and preoperative WL, and the relationship between the two.

Conclusion: Preoperative WL via VLCD was associated with reduced postoperative WL after BS, with no significant effect on complications, long-term TWL or %EBMIL. This challenges the notion that preoperative WL via VLCD should be mandated for better postoperative outcomes.