The Impact of Menopausal Status on Body Composition Following Roux-en-Y Gastric Bypass Surgery

Abstract

Introduction: Menopausal women are prone to muscle loss due to reduced anabolic signaling and decreased physical activity associated with declining estrogen levels. These changes impair muscle protein synthesis. Following Roux-en-Y gastric bypass (RYGB), calorie restriction, impaired protein absorption, and vitamin deficiencies may further exacerbate muscle loss. This study aimed to evaluate whether menopausal status has an additive effect on body composition, particularly fat-free mass (FFM) loss, at 12 months following RYGB. Patients and Methods: Women who underwent RYGB between 2006 and 2021, with a minimum 12-month follow-up, including body composition assessment via bioelectrical impedance analysis, were categorized into two groups: premenopausal (<45 years, no history of bilateral oophorectomy) and postmenopausal (>55 years). Weight loss and body composition changes were compared between groups at 12 months post-surgery. Results: The study included 187 premenopausal and 47 postmenopausal women. Baseline weight and body mass index (BMI) did not differ significantly between groups. Both groups achieved significant % total weight loss (%TWL) at 12 months, with no statistically significant differences. Postmenopausal women had significantly lower baseline FFM, and this difference persisted at 12 months following surgery. Additionally, postmenopausal women exhibited a significantly larger waist circumference preoperatively, which remained greater postoperatively despite a similar degree of reduction. At 24 months, follow-up data were available for 48 premenopausal and 15 postmenopausal women (lost to follow-up: 139 and 32, respectively). Conclusion: Compared to premenopausal women, postmenopausal patients exhibited lower FFM, a difference that persisted without additional postoperative deterioration at 12 months.