Comparative Effects of Sleeve Gastrectomy vs. Roux-en-Y Gastric Bypass on Phase Angle and Bioelectrical Impedance Analysis Measures: A Systematic Review and Meta-Analysis.

The objective of this meta-analysis was to determine the impact of bariatric surgery on phase angle (PhA) and other bioimpedance measures among adults with obesity, comparing the effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). A systematic review and meta-analysis were conducted following PRISMA guidelines, including studies up to May 2024 from MEDLINE, Scopus, Cochrane Library, and Web of Science. Eligible studies assessed PhA changes pre- and post-bariatric surgery in adults with BMI ≥ 30 kg/m. Data on PhA, fat mass (FM), fat-free mass (FFM), body cell mass (BCM), weight, and BMI were extracted and analyzed. Thirteen studies with a total of 1124 patients were included. Significant PhA reductions were observed at 6 months post-surgery (effect size: -1.00; 95% CI: -1.11 to -0.89; < 0.001), with a more substantial reduction in RYGB patients compared to SG. FM and FFM decreased significantly at 12 months (FM: -27.58; 95% CI: -32.58 to -22.57; < 0.001; FFM: -10.51; 95% CI: -12.81 to -8.94; < 0.001). Weight and BMI showed marked reductions at 6 months (Weight: -31.42 kg; 95% CI: -37.28 to -25.26; < 0.001; BMI: -11.39; 95% CI: -12.60 to -10.18; < 0.001), with sustained decreases at 12 and 24 months. Bariatric surgery significantly reduces PhA, FM, FFM, weight, and BMI, with initial greater impacts observed in RYGB compared to SG. PhA shows potential as a marker for monitoring post-surgical recovery and nutritional status. Further long-term studies and standardized measurement protocols are recommended to optimize patient management.