Laparoscopic sleeve gastrectomy (LSG) is the most preferred bariatric surgical procedure worldwide. LSG, a restrictive surgical method, has also proven to be a good metabolic surgery option. In this study, we examined weight loss and changes in metabolic parameters in our patients in the first year after LSG. In this retrospective cohort study, preoperative and postoperative first-year body mass index (BMI) changes, biochemical and hormonal analysis results, and excess weight loss (EWL) rates of 1,137 patients who underwent LSG were evaluated. The median age of patients undergoing LSG was 39 years, and 943 (82.9%) of the patients were female while 194 (17.1%) were male. Preoperative BMI was 45.91 kg/m2 and postoperative first-year BMI was 28.98 kg/m2 (p<0.01). Fasting blood glucose, alanine aminotransferase, aspartate aminotransferase, total cholesterol, triglycerides, insulin, free thyroxine, thyroid-stimulating hormone, and HbA1c percentage levels were significantly low in the postoperative first year (p<0.001). EWL was 81.0% (68.4-97.9%) and sufficient weight loss (SWL; ≥50% of EWL) was 92.2% in the postoperative first year. Median age, the prevalence of type 2 diabetes mellitus, preoperative fasting plasma glucose levels, and preoperative triglyceride levels were higher in the SWL group than they were in the group with insufficient weight loss (EWL of <50%). Factors such as male sex, body weight, and triglyceride levels were positively correlated with adequate weight loss, while BMI and total cholesterol levels were negatively correlated with adequate weight loss. Patients with BMI of >46.87 kg/m2 had a higher rate of adequate weight loss. LSG is a bariatric surgical procedure providing satisfactory weight loss and metabolic outcomes in the short term. Weight loss success in the first year after LSG was higher among patients with a baseline BMI of 46 kg/m2.