Fat mass, fat-free mass, and resting metabolic rate in weight-stable sleeve gastrectomy patients compared with weight-stable nonoperated patients.

Background: There is evidence that body composition and resting metabolic rate (RMR) in weight-stable patients after Roux-en-Y gastric bypass and duodenal switch is similar to that of nonoperated individuals within the same body mass index (BMI) interval. Currently, data concerning fat mass (FM), fat-free mass (FFM), and RMR on weight-stable patients after sleeve gastrectomy (SG) are lacking.

Objectives: To assess FM, FFM, and RMR, in a selected and homogenous population of weight-stable SG patients (WSSG) and compare them with those obtained from healthy normal weight-stable nonoperated (WSNO) volunteers controls of similar sex, age, and BMI.

Setting: University hospital, Italy.

Methods: We assessed total weight, FM, and FFM by bioelectrical impedance assay, and RMR by indirect calorimetry, in 70 WSSG patients (47 females, 23 males) at a mean follow-up of 3.2 ± 2.1 years after SG and compared them with 70 healthy WSNO volunteers, as controls (47 females, 23 males).

Results: There was no significant difference between WSSG and WSNO groups concerning total weight (males, 72 ± 2.66 versus 72.8 ± 1.99 kg, P = .0254; females 65.1 ± 2.53 versus 63.7 ± 2.87 kg, P = .0139), FM (males, 17.7 ± 1.53 versus 16.7 ± 1.57 kg, P = .0341; females 19.6 ± 0.50 versus 18.5 ± 2.85 kg, P = .0104), FFM (males, 54.3 ± 3.07 versus 56.1 ± 3.30 kg; P = .049; females 45.5 ± 2.29 versus 45.1 ± 1.13 kg, P = .287), and RMR (males, 1541 ± 121.3 versus 1463 ± 74.4 kcal/d; P = .0118; females 1214 ± 54.9 versus 1250 ± 90.1 kcal/d, P = .0215).

Conclusion: At a mean follow-up of 3.2 ± 2.1 years after SG, WSSG patients of both sexes have a FM, FFM, and RMR comparable to that of healthy WSNO individuals within the same age and BMI interval. These findings further support bariatric surgery-induced weight loss as a physiologic process and indicate that young patients, in the setting of an adequate preoperative and postoperative specific diet and moderate physical activity, do not suffer from excessive FFM depletion after SG in the mid-term.