Background: According to the results of an electrocardiogram (ECG), a higher body mass index (BMI) indicates body fat and is linked toa higher risk of cardiovascular illnesses. A noninvasive ECG signal called P-wave dispersion (Pd) can predict the likelihood of an atrialarrhythmia and reflects atrial remodeling. Pd is calculated by computing the difference between the maximum and minimum P-wavelengths captured from the 12 ECG lead recordings. To assess the early-stage risk of acquiring cardiovascular illnesses, we investigatedthe effect of BMI on P-wave dispersion in healthy, overweight, and obese adults. Materials and Methods: Depending on their body massindex (BMI), we divided 200 participants into three groups (normal weight, overweight, and obese) during a comparative cross-sectionalstudy. We measured 12-lead surface ECG and P-wave dispersion in study participants. Results: Mean P-wave lengths were 33.23(±6.08), 33.15(± 5.16), and 46.15 (± 5.37), respectively, for people who were normal weight, overweight, and obese. Between the normalweightand obese groups and the overweight and obese groups, there was a statistically significant difference (p < 0.001), according toTukey’s post-hoc analysis. However, the normal-weight and overweight groups showed no statistically significant difference (P = 0.997).Pearson’s correlation analysis shows that P-wave dispersion and BMI showed a significant positive connection (r = 0.632). Conclusion:A higher BMI is linked to a longer P-wave duration and dispersion, even in healthy adults. The likelihood of left atrial hypertrophy andatrial arrhythmia increases with a prolonged P-wave duration. This study emphasizes the importance of raising awareness about theneed to adopt healthy lifestyles to avoid the harmful effects of obesity on the heart