Aims:
Bariatric surgery is associated with improvement in cardiometabolic health. Our study aims to compare body composition changes, resting energy expenditure (REE) and insulin sensitivity in morbidly-obese patients compared to healthy controls at baseline and 6 months after sleeve gastrectomy (SG).
Methods:
Non-diabetic subjects (N=9, age 21-50 years) undergoing SG were studied at baseline and 6 months after surgery. Non-obese subjects (N=9, age 22 - 47 years) were used as controls and were studied once. Study participants undergo a body composition analysis using bioimpedance analysis, indirect calorimetry to measure REE and glucose homeostasis quantification using oral glucose tolerance testing and hyperinsulinemic-euglycemic clamp.
Results:
After bariatric surgery, there were significant decreases in weight (118.5 ± 23.3 vs 91.9 ± 16.6 kg), BMI (40.2 ± 4.5 vs 31.3 ± 2.9 kg/m2) and fat mass (56.8 ± 14.6 vs 37.0 ± 12.9 kg). However, these remained higher compared to the non-obese controls. Obese subjects had significantly higher REE at baseline compared to controls (2234.7 ± 544.1 vs 1461.4 ± 314.1 kcal/day; 36.3 ± 4.0 vs 28.7 ± 2.6 kcal/kg FFM/day). Although total REE decreases after surgery (2234.7 ± 544.1 vs 1772.5 ± 376.9 kcal/day), it did not change significantly when quantified based on fat-free mass, FFM (36.3 ± 4.0 vs 34.3 ± 5.2 kcal/kg FFM/day). Postoperatively, there was a significant decrease in fasting blood glucose levels (106.3 ± 11.9 vs. 91.7 ± 6.4 mg/dL) with improvement in insulin sensitivity (2.0 ± 0.8 vs. 4.9 ± 1.2 mg/kg/min), insulin metabolic clearance rate (12.1 ± 3.0 vs. 15.9 ± 3.3 ml/kg/min) and glucose disposition index (1.7 ± 1.6 vs 4.9 ± 2.6).
Conclusion:
Weight loss following bariatric surgery was mainly secondary to fat mass loss (74%) and associated with improvements in various glucose homeostasis parameters and preserved REE quantified based on FFM.