Background: The potential effect of bariatric surgery on weight reduction and improvement of associated comorbidities is known, but the ratio obtained between the components of body weight, including lean body mass, body fat mass, and bone mass, is still not determined. This study aims to verify the changes in body composition during the first year after bariatric surgery.
Methods: We conducted a prospective observational cohort study. Fifty patients who underwent bariatric surgery and maintained follow-ups were selected. Patients were assessed preoperatively and postoperatively for periods of 1, 3, 6, and 12 months using tetrapolar bioelectrical impedance analysis and laboratory testing of lipids and serum albumin levels. Data were statistically analyzed.
Results: Statistically significant differences (p < 0.001) were obtained between the preoperative and 12-month evaluation respectively, for body mass index (BMI) (45.8 ± 7.5 to 30.0 ± 4.8 kg/m2), FM (64.7 ± 15.5 to 30.6 ± 9.8 kg), PFM (51.6 ± 4.17 to 37.3 ± 7.6%), and total cholesterol levels (197.1 ± 49.8 to 169.8 ± 31.0 mg/dL). The decrease in PFM shows a better proportion between the body components. PFM showed significantly higher decrease in males than in females (p = 0.012). Lean body mass (p = 0.000) reduction was highest for patients operated by the Unified Health System (SUS, Government of Brazil) probably because of its few financial resources to maintain postoperative care.
Conclusion: The change in body composition of patients who underwent Roux-en-Y gastric bypass was statistically significant for all variables examined during the first year postoperatively. This shows the effectiveness of the surgical procedure and clinical protocol set, which tends to favor a better health prognosis and weight maintenance in the long term.
Keywords: Bariatric surgery; Bioelectrical impedance analysis; Body composition; Gastrointestinal bypass; Morbid obesity.