Bariatric and Metabolic Surgery: Comparative Analysis of Weight Loss and Dietary Intake Across Surgical Techniques

Background: Obesity is a major global public health concern associated with comorbidities such as type 2 diabetes mellitus (T2DM) and metabolic syndrome. Bariatric and metabolic surgeries are effective interventions for weight loss and metabolic improvement; however, outcomes may vary depending on the surgical technique. Objective: To evaluate weight loss, dietary intake, and glycemic control in patients undergoing different bariatric and metabolic surgical procedures over one year of nutritional follow-up. Methods: This retrospective, quantitative, and exploratory study analyzed medical records of 100 adult patients who underwent bariatric or metabolic surgery in a private clinic in Curitiba, Brazil. Procedures included Roux-en-Y gastric bypass, sleeve gastrectomy, transit bipartition, single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S), and ileal interposition. Data were collected preoperatively and at 1, 6, and 12 months postoperatively. Variables included body mass index (BMI), percentage of weight loss, dietary intake, physical activity, water intake, and glycated hemoglobin (HbA1c). Results: The sample comprised 62% women, with a mean age of 47 years. Mean BMI decreased from 38.4 +- 5.3 kg/m2 to 25.74 +- 3.5 kg/m2 after one year. RYGBachieved the greatest weight loss (35.4%). Caloric intake decreased at 6 months and increased moderately at 12 months, while protein intake per kilogram increased. Improvements in dietary patterns were observed; however, persistent deficiencies in iron, calcium, and vitamin D remained. HbA1c improved from 7.3% to 5.7%. Conclusion: Bariatric and metabolic surgeries promote significant weight loss, improved glycemic control, and positive lifestyle changes. Persistent micronutrient deficiencies highlight the need for continuous nutritional monitoring and multidisciplinary care.