Background: Obesity is one of the most prevalent nutritional disorders globally, affecting nearly every body system, including pulmonary functions. Body Mass Index (BMI) is the most commonly used parameter to determine and classify obesity. However, Waist Circumference (WC) and Waist-to-Hip Ratio (WHR) are also important measures, particularly for identifying central obesity. Aim: To determine the effect of obesity on Peak Expiratory Flow Rate (PEFR) and to examine its correlation with these three obesity parameters. Material and Methods: A cross-sectional study was conducted to assess the impact of BMI, WC, and WHR on PEFR among 100 male participants aged 18-25 years. The study also aimed to evaluate the correlation between PEFR and these parameters of obesity. Results: Among the 100 male participants, 77 had normal BMI, 13 were classified as overweight, and 10 were classified as obese. The observed PEFR (L/min) values were 484.04±13.80 in the normal group, 477.23±11.70 in the overweight group, and 464.94±16.96 in the obese group. Significant differences were found between the normal and obese groups, as well as between the overweight and obese groups. Based on WC and WHR, the prevalence of obesity was 27% and 32%, respectively, with statistically significant reductions in PEFR among obese individuals using both measures. A negative correlation between PEFR and all three parameters (BMI, WC, and WHR) was also observed.Conclusion:Obesity has a detrimental effect on PEFR. While BMI exerts the strongest influence on PEFR, indicating the impact of total body fat, abdominal obesity (measured by WC and WHR) is also an important factor affecting respiratory health.