Introduction <p>Sleeve gastrectomy (SG) is widely recognized for its association with gastroesophageal reflux disease (GERD) and reduced sustained weight loss in the long term. The Single Anastomosis Sleeve Ileal (SASI) bypass was introduced as an alternative to enhance the metabolic benefits of SG, improve GERD outcomes, address nutritional challenges of ileal bypasses, and maintain duodenal access.</p> Methods <p>This study is a systematic review and meta-analysis of the comparative safety and efficacy of SASI bypass vs SG. A literature search in PubMed, Scopus, Embase, and Cochrane identified 234 articles after duplicate removal. Primary outcomes were GERD remission and complication rates over the follow-up period of each study including all complications reported by the authors, while secondary outcomes included weight loss and obesity-related condition remission.</p> Results <p>Thirteen studies, including 2 RCTs and eleven observational studies, analyzed 960 SG and 396 SASI bypass patients. SASI bypass showed significantly higher GERD remission (OR 7.64; 95% CI [2.81; 20.78]; P &lt; 0.001; I² = 0%) but with an overall higher complication rate after sensitivity analysis (OR 4.39; 95% CI [1.44–13.40]; P = 0.009; I² = 59%). It also had superior excess weight loss (MD = 9.61; 95% CI [5.8; 13.43]; P &lt; 0.01) and better dyslipidemia remission (OR 2.19; 95% CI [1.07; 4.48]; P = 0.031). Hypertension and OSA remission rates were similar between techniques. Type 2 diabetes mellitus (T2D) remission rates were high after SASI bypass (OR 4.20; 95% CI [2.17; 8.11]; P &lt; 0.001).</p> Conclusion <p>SASI bypass offers superior GERD remission over SG but with potentially higher associated morbidity. Both techniques effectively promote weight loss and obesity-related condition remission, with SASI having a slight metabolic advantage due to intestinal bypass. Further research including prospective studies are needed to validate these findings and optimize postoperative care.</p>