Background <p>Bariatric surgeries, such as laparoscopic sleeve gastrectomy (LSG), not only result in significant weight loss but also improve the inflammatory state in obese patients. This study aimed to investigate the effects of LSG on weight loss and inflammation status in bariatric patients 1-year post-procedure.</p> Methods <p>This prospective cohort study was conducted from September 2022 to May 2024. Fifty obese adults were enrolled for LSG. All patients underwent assessments of body measurements, as well as levels of interleukin-6 (IL-6) and interleukin-10 (IL-10) at baseline, and then at 3 and 12&#xa0;months post-surgery.</p> Results <p>Twelve months post-surgery, body measurements showed a significant reduction, with a median excess weight loss (%EWL) of 56.8%, indicating the clinical success of the bariatric procedure. %EWL showed a strong correlation with waist circumference (<i>R</i> = − 0.738, <i>p</i> &lt; 0.00001). A logistic regression model indicated that a reduction of just 1&#xa0;cm in initial waist circumference increases the likelihood of a positive outcome in laparoscopic sleeve gastrectomy by 12%. Moreover, a significant increase was observed for IL-10 (<i>p</i> &lt; 0.0001), simultaneously with a significant decrease in IL-6 (<i>p</i> &lt; 0.0001).</p> Conclusions <p>This study provides valuable evidence supporting the benefits of laparoscopic sleeve gastrectomy for both weight loss and reducing inflammation. Waist circumference emerged as a strong predictor of metabolic success 1-year post-surgery, while increased IL-10 levels signaled positive immunological changes.</p>