Sex differences in visceral adipose tissue post-bariatric surgery compared to matched non-surgical controls

Abstract

OBJECTIVE AND METHODS: Given the profound weight loss after gastric banding and bypass we compared fat compartmentalization by whole body magnetic resonance imaging in women and men after these procedures to two groups of non-surgical controls who were either matched for age, weight and height or were of lower body mass index (BMI). RESULT: In women post-surgery (n=17; BMI 31.7 kg/m(2)) there was lower visceral adipose tissue (VAT) (1.4 vs 2.5 kg; P<0.01) compared with matched controls (n=59; BMI 32.1 kg/m(2)). In contrast, VAT (5.3 vs 5.4 kg) was nearly identical in men post-surgery (n=10; BMI 34.1 kg/m(2)) compared with matched controls (n=10; BMI 32.1 kg/m(2)) even though the degree of weight reduction was not significantly different from women (27.4 vs 32.6%). Furthermore, VAT when adjusted for total adipose tissue (TAT) was 43% less in women post-surgery (1.2 vs 2.1 kg; P=0.03) than in controls with lower BMI (25.1 kg/m(2)). After adjustment for TAT, subcutaneous adipose tissue in women post-surgery was significantly greater than matched controls (35.1 vs 34.2 kg; P=0.03). There was a significant negative correlation of VAT and the degree of weight loss in women (r=-0.57; P=0.018) but this relationship was not significant in men (r=-0.39; P=0.27). Skeletal muscle was lower in both sexes compared with matched controls (women, 21.8 vs 23.1 kg; men, 32.5 vs 35.5 kg). CONCLUSION: Prospective studies are necessary to confirm if there is a sexual dimorphism in the effects of bariatric surgery on body composition.

Figure 1

Relationships between TAT and body weight, and between VAT and TAT and percent weight loss in women (left panel) and men (right panel). Open circles and squares represent non-surgical controls matched for age, weight, and height to the post-surgery subjects represented by closed circles and squares. Solid lines represent linear regression from post-surgery subjects; dotted lines represent linear regression from non-surgical matched controls. r indicates Pearson correlation coefficients.

Figure 2

Relationships between VAT with TAT and percent weight loss in women post-BND (left panel) and post-GBP (right panel). Solid lines represent linear regression. r indicates Pearson correlation coefficients.