Background : Now a days Obesity become the most important cause of respiratory problem in young individuals around 40% of adults worldwide are either overweight or obese. Aims and Objectives: By assessing the respiratory function with the help of spirometry and impulse oscillometry we can assess the respiratory defect in obese and also show the impact of obesity on respiratory system. Materials and Methods: we perform the Pulmonary function tests (PFT) and Impulse oscillometry(IOS) in various age group individuals by jaeger machine and compare it with the predicted value. Results: Decreased in Forced vital capacity (FVC) and Forced expiratory volume in first one second (FEV1) in obese individuals and in IOS there was a very significant decline in Resistance(R). Conclusion: Decreased respiratory functions in obese individual and IOS is better test for obstructive changes