Effects of Roux-en-Y gastric bypass surgery on visceral and subcutaneous fat density by computed tomography.

We aimed to test the hypothesis that noninvasive fat density by computed tomography (CT) increases after Roux-en-Y gastric bypass (RYGB) and correlates with improved cardiometabolic risk. We examined 21 obese adults before and 12 months after RYGB and 16 obese nonsurgical controls followed for 12 months. Visceral (VAT) and subcutaneous adipose tissue (SAT) density increased after RYGB (P < 0.0001) while remaining stable in controls (P ≥ 0.1). In RYGB subjects, 12-month increase in VAT density correlated with decreased C-reactive protein (CRP) independent of change in VAT area or BMI (both P < 0.05). Twelve-month increase in SAT density correlated with increased HDL cholesterol independent of change in SAT area (P = 0.048), BMI (P = 0.03), or statin use (P = 0.002), and 1 unit increase in SAT density had increased odds of higher total abdominal fat loss (P = 0.002).