Key result
Roux-en-Y gastric bypass linked to ~47% visceral fat reduction alongside early but stabilizing muscle loss.
Why the study?
Outcomes of Roux-en-Y gastric bypass on skeletal muscle, visceral adipose tissue, and subcutaneous adipose tissue remain inconsistent due to measurement limitations.
Does Roux-en-Y gastric bypass reduce visceral and subcutaneous adipose tissue volumes while preserving skeletal muscle in female patients with severe obesity?
Does Roux-en-Y gastric bypass reduce visceral and subcutaneous adipose tissue volumes while preserving skeletal muscle in female patients with severe obesity?
Effect estimate: 14% decline in SM volume at 3 months, plateau at 6 months; 31% reduction in SAT and 47% reduction in VAT volumes at 6 months post-RYGB
Absolute Event Rate: -14% vs 0%
p-value: p=<0.001 for SAT and VAT decreases; p=0.007 for SM linearity deviation
Roux-en-Y gastric bypass leads to large relative reductions in visceral and subcutaneous adipose tissue volumes at 6 months, while skeletal muscle volume shows a more modest relative decline at 3 months and then stabilizes.
Roux-en-Y gastric bypass (RYGB) is associated with substantial weight loss and improved obesity-related comorbidities. However, outcomes on body composition, particularly skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) remain inconsistent due to limitations in measurement techniques. Evaluate longitudinal changes in SM, VAT, and SAT volumes (cm3) following RYGB using Data Analysis Facilitation Suite (DAFS), an automated computed tomography (CT) analysis software. In this prospective pilot study, nine female patients underwent low-dose abdominal and pelvic CT imaging at baseline, 3-, and 6-months post-RYGB. Volumetric analysis from the ninth thoracic veterbra (T9) to the sacrum was performed using DAFS. Changes in SM, VAT, and SAT were assessed using paired t-tests. Participants (mean ± SD; age 35 ± 9 years, BMI 48 ± 10 kg/m²) experienced substantial weight loss (14 ± 5% at 3 months, 25 ± 7% at 6 months; p < 0.001). SAT and VAT volumes decreased significantly by 21% and 27% at 3 months, and by 31% and 47% at 6 months, respectively (all p < 0.001). In contrast, SM volume showed a significant decline of 14% at month 3 (p < 0.001) and then plateaued thereafter. The changes over time differ substantially among SM, VAT and SAT after Roux-en-Y gastric bypass, reflecting the distinct physiological responses and metabolic improvement of different tissue types. Larger and longer clinical studies are needed to validate these findings. • RYGB leads to large relative reductions in visceral and subcutaneous adipose tissue (VAT and SAT) volumes at 6 months while skeletal muscle (SM) volume shows a more modest relative decline at 3 months and then stabilizes at 6 months. • There are meaningful correlations between SM and SAT, whereas the correlations between VAT and SAT, and between SM and VAT, appear weak or negligible. • Findings suggest RYGB is associated with skeletal muscle preservation relative to fat loss, but larger, longer-term studies are needed to confirm these results and their clinical implications.
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Snoekx et al. (2026) studied Adult female patients with severe obesity (mean BMI 48 ± 10 kg/m²) undergoing Roux-en-Y gastric bypass including primary and conversion cases (n=9). Roux-en-Y gastric bypass (RYGB) vs. Baseline preoperative measurements was evaluated on Percentage change in skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) volumes measured by automated CT volumetric analysis (14% decline in SM volume at 3 months, plateau at 6 months; 31% reduction in SAT and 47% reduction in VAT volumes at 6 months post-RYGB, p=<0.001 for SAT and VAT decreases; p=0.007 for SM linearity deviation). Roux-en-Y gastric bypass led to 31% decrease in subcutaneous adipose tissue and 47% decrease in visceral adipose tissue volumes at 6 months, with a 14% early decline and subsequent stabilization of skeletal muscle volume in severely obese adult females.
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