Epicardial adipose tissue (EAT) is closely associated with atrial fibrillation (AF), suggesting it may be one of the causes of AF progression. However, it is unclear whether atrial fibrillation affects EAT. This study aimed to demonstrate that sinus rhythm restoration reduces EAT volume (EATV) through left atrial reverse remodeling (LARR). We analyzed data from 247 patients who underwent cryoballoon ablation (CBA) for AF. EATV was assessed using contrast-enhanced computed tomography with three-dimensional analysis workstation, evaluating EATV surrounding the entire heart (Total-EATV) and left atrial EATV (LA-EATV) at baseline and 6 months post-CBA. At 6 months, all patients but one with persistent AF were in sinus rhythm. Total-EATV and LA-EATV were both significantly decreased in patients with persistent AF (n=33) (Total-EATV: 148.8±53.3 to 142.9±53.5 mL, p=0.01; LA-EATV: 26.8±11.3 to 25.2±10.7 mL, p=0.01). No changes were observed in patients with paroxysmal AF (n=214). Persistent AF was more strongly associated with LARR than paroxysmal AF (odds ratio [OR]: 2.34, 95% confidence interval [CI]: 1.01-5.44, p=0.05). LARR showed an independent correlation with both Total-EATV and LA-EATV reduction (OR: 1.78, p=0.04 and OR: 2.80, p<0.001, respectively). These findings suggest a novel "AF begets EAT" theory, complementing the previously accepted role of EAT as a cause of AF and supporting the "AF begets AF" mechanism.