The potential effect of whey protein supplementation in post-bariatric surgery patients: a systematic review and meta-analysis of randomized controlled trials.

Abstract

Bariatric surgery is an effective intervention for severe obesity, and postoperative nutritional management significantly influences surgical outcomes. Currently, the impact of whey protein supplementation on patients following bariatric surgery remains uncertain. This study aims to explore the role of whey protein supplementation in this patient population through a meta-analytical approach. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement. Randomized controlled trials (RCTs) investigating whey protein supplementation in patients after bariatric surgery and published before August 2025 were systematically identified through online databases, including PubMed, the Cochrane Library, and Embase, as well as grey literature sources, including OpenGrey and ProQuest Theses and Dissertations. Data related to anthropometry, body composition, and lipid profiles, including endpoint values and change values, were extracted for quantitative analysis. The quality of evidence was evaluated using the Grading of Recommendations Assessment Development and Evaluation system. Five RCTs encompassing 267 patients were included in the analysis. The results of the meta-analysis concerning anthropometry and body composition suggested that whey protein supplementation may alleviate the reduction in body weight ( p = 0.017) and body mass index ( p = 0.027), which may be attributable to decreases in fat mass ( p = 0.024) and the preservation of fat-free mass ( p = 0.003). Conversely, the pooled estimation results suggest that whey protein supplementation may have a limited impact on lipid profiles. The evidence quality for all parameters was rated as moderate to very low. Current evidence suggests that supplementation with whey protein post-bariatric surgery may offer potential benefits. However, the current evidence remains limited and further studies are needed to confirm our findings. https://www.crd.york.ac.uk/PROSPERO/view/CRD420251126055, identifier (CRD420251126055).