Background <p>Obesity is associated with deleterious metabolic and hemodynamic changes resulting in cardiac remodeling. Bariatric surgery is highly effective for both weight reduction and reverse cardiac remodeling. However, whether these changes depend on the magnitude of weight loss is unknown.</p> <p>This study aims to compare cardiac structure and diastolic function before and after bariatric surgery and examine its association with body mass index (BMI) variation.</p> Methods <p>Consecutive bariatric patients operated between June 2023 and June 2024 were screened for inclusion. Patients with a) previous bariatric surgery, b) moderate to severe valvular disease, c) those without follow-up 1&#xa0;year after the intervention, or c) those who declined to participate were excluded. Cardiac structure and diastolic function were assessed preoperatively and 12&#xa0;months after the surgery.</p> Results <p>A sample of 70 patients was analyzed. After 12&#xa0;months, the left atrial (LA) volume index went from 25.0 ± 6.1&#xa0;ml/m² to 29 ± 7 (p &lt; 0.001) whereas diastolic and systolic left ventricular (LV) diameters decreased from 4.98 ± 0.43&#xa0;cm to 4.53 ± 0.41&#xa0;cm (p &lt; 0.001) and from 3.17 ± 0.33&#xa0;cm to 2.88 ± 0.28&#xa0;cm (p &lt; 0.001), respectively. LV mass index declined from 75 ± 15 to 65 ± 14&#xa0;g/m² (p &lt; 0.001). In univariate linear regression analysis, LA volume index, diastolic and systolic LV diameters, and LV mass index were not associated with BMI reduction. These results were similar after adjustment for age and sex. The prevalence of grade I and grade II diastolic dysfunction decreased to 1 (1.4%) and 14 (20%), respectively (p = 0.2) with no association with BMI change.</p> Conclusion <p>Significant reverse cardiac remodeling occurs after bariatric surgery with no association with BMI reduction. Further research is warranted to clarify the beneficial cardiovascular effects of bariatric surgery beyond weight loss.</p>