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

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. 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. 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. 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.