Preoperative carbohydrate loading in elective colorectal surgery: postoperative complications and outcomes, a systematic review and meta-analysis

Purpose This study aimed to evaluate the clinical impact of preoperative carbohydrate loading in elective colorectal surgery. Methods The review followed the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. A systematic search was conducted in MEDLINE (via PubMed), Scopus and Cochrane CENTRAL (via Wiley) to 1 August 2025. All randomised controlled trials (RCTs) investigating preoperative carbohydrate loading in elective colorectal surgery were assessed. The primary outcome was overall postoperative complications; secondary outcomes included specific types of complications, gastrointestinal recovery time, independent mobilisation, and length of stay (LOS). Results A total of 3,483 citations were screened, yielding 13 RCTs with 996 patients (469 received preoperative carbohydrate loading, 198 consumed water and 329 followed overnight fasting). Carbohydrate loading did not significantly affect overall complications or mortality. Secondary outcomes suggested reduced respiratory infections (OR 0.35; p = 0.04), shorter time to first flatus (MD − 0.60; p < 0.01), earlier defecation (MD − 0.58; p = 0.01), shorter LOS (MD − 0.98; p < 0.01) and earlier mobilisation (MD − 0.49; p < 0.01). Conclusion Preoperative carbohydrate loading was not associated with a statistically significant reduction in overall postoperative complications. Sensitivity analyses suggested limited robustness of the primary outcome. Secondary outcomes suggested faster gastrointestinal recovery, fewer respiratory infections, earlier mobilisation and shorter length of stay; however, these findings should be interpreted cautiously given heterogeneity across trials and variability in perioperative pathways. Further high-quality multicentre randomised controlled trials are needed to confirm these effects in contemporary ERAS pathways.