Background:Obesity is linked to a higher risk of insulin resistance, high blood pressure, abnormal cholesterol levels, cardiovascular disease, type 2 diabetes, gallstones and gallbladder inflammation, breathing problems, and certain types of cancer. This was a comparative study of pulmonary function test between obese and non-obese adult males.Material and methods: In the present study total 120 subjects were selected which includes 60 normal weight and 60 obese young adultmales who were categorized based on WHO criteria of Body Mass Index. These subjects were selected by a simple random sampling method from the MBBS students of Nalanda Medical College and Hospital, Patna.The selected group of subjects were categorized into normal weight and obese based on the chart provided by WHO for body mass index. Pulmonary Function Tests Between Obese and Non-Obese Young Adult Males were compared.Results: Among individuals aged 18-20 years, 43% were of normal weight, while 23% were obese. In the 21-22 years age group, 37% were of normal weight, with a higher percentage, 43%, being obese. For those aged 23-24 years, 20% were of normal weight, and 33% were classified as obese. The overall mean age for the normal weight group was 20.81 ± 1.79 years, compared to 21.78 ± 1.57 years for the obese group. Although the data suggests a trend of increasing obesity with age, the p-value of 0.302 indicates that the age distribution differences between the normal weight and obese groups are not statistically significant.Conclusion: The analysis of pulmonary function test parameters revealed notable differences between normal weight and obese young adult males. Obese individuals showed significantly lower Forced Vital Capacity (FVC) and Forced Expiratory Volume in the first second (FEV1) compared to those with normal weight.