Standardized Pre- and Early Postoperative Dietary Protocols After Bariatric and Metabolic Surgery: A 20-Year...

Structured dietary management before and after bariatric and metabolic surgery is essential for reducing early postoperative complications, yet evidence describing tolerance and clinical outcomes across different surgical techniques remains limited. This study evaluated a standardized preoperative preparation diet and a uniform postoperative consistency-progression protocol implemented over two decades in a high-volume reference center.

This retrospective cohort included 622 adult patients who underwent Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), ileal interposition, SADI-S, or gastric bipartition between 2004 and 2024. All patients completed a 10-day anti-inflammatory preoperative diet followed by a two-stage liquid regimen. Postoperatively, patients followed a structured progression from liquid to pureed and finally to solid foods over 30 days. Early outcomes included gastrointestinal symptoms and the occurrence of fistulas or drain use.

The cohort comprised 66.9% women, with RYGB being the most frequent procedure (55.5%), followed by SG (24.4%), ileal interposition (14.0%), SADI-S (3.9%), and bipartition (2.3%). Overall prevalence in the first postoperative month was 9.0% for constipation, 2.7% for diarrhea, 8.8% for vomiting, 2.4% for nausea, 0.6% for reflux, and 0.2% for dumping. Fistulas and drain requirements each occurred in 0.5% of patients. Across techniques, 79.9% of patients remained symptom-free; ileal interposition showed the highest symptom rate (29.9%).

A uniform progression protocol following a structured preoperative diet was associated with low rates of gastrointestinal symptoms and postoperative complications across multiple bariatric procedures. These findings suggest that a physiology-based dietary pathway may be safely implemented during early postoperative recovery. Larger prospective studies are warranted, particularly for emerging ileal techniques.