Changes in Body Composition, Dietary Intake, and Substrate Oxidation in Patients Underwent Laparoscopic Roux-en-Y Gastric Bypass and Laparoscopic Sleeve Gastrectomy: a Comparative Prospective Study.

PURPOSE: Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are the most popular procedures to treat morbid obesity among bariatric surgeries. However, only few studies have compared the changes in body composition, dietary intake, and substrate oxidation after LRYGB and LSG. Therefore, the present study was conducted to compare the changes in body composition, dietary intake, and substrate oxidation 6 months postoperatively in obese patients who underwent LRYGB and LSG.

MATERIALS AND METHODS: In this prospective study, a total of 43 adult obese patients participated (LRYGB = 22 and LSG = 21). Their body composition was measured by bioelectric impedance analysis. Dietary intake was assessed using 3-day food record. Substrate oxidation was measured by indirect calorimetry. All participants were followed up for 6 months.

RESULTS: The percentage of weight loss was 22.8 ± 4.5 and 23.3 ± 5.7% in LRYGB and LSG, respectively. Fat mass (FM), fat-free mass (FFM), and percentage of fat mass (PFM) significantly reduced in LRYGB and LSG, while the percentage of fat-free mass (PFFM) significantly increased in both surgeries. Dietary energy intake significantly reduced by 63.5 ± 30.6% in LRYGB and 66.7 ± 20.1% in LSG. Dietary intake of protein, carbohydrate, fat, and fiber significantly decreased in each group. The percentage of energy from protein, carbohydrate, and fat did not change in each group. Protein oxidation and carbohydrate oxidation significantly reduced in both procedures postoperatively. Changes in body composition, dietary intake, and substrate oxidation from baseline were equal in LRYGB and LSG.

CONCLUSION: Therefore, LRYGB and LSG have similar effect on total and regional FM and FFM, dietary macronutrients intake, and substrate oxidation.