Introduction: Obesity has become a major epidemic causing serious public health concern especially in developing countries. The proportion of children and adolescents in the general population who are overweight and obese has doubled over the past two decades in developed and developing countries including India. Interventions in school are an important strategy to prevent obesity among them. Objectives: To find out the changes in anthropometric parameters and practices following lifestyle interventions related to obesity among school-going adolescents. Methods: A quasi-experimental study conducted from June 2016 to August 2018, in two private schools. A total of 173 students, 86 from the control school and 87 from the intervention school were included. Study participants were interviewed using a pre-designed, pretested and semi-structured interview schedule at baseline and after an intervention. Control school students were given printed educational materials in the form of a carefully prepared poster and intervention school students were intervened for one year by interactive sessions with an integrated educational package, personal and parental counselling for overweight/ obese students followed by reinforcement. Results: No significant difference was seen in anthropometric measurements among the control and intervention group at baseline. In the intervention group, a significant decrease was observed in body mass index (BMI) (P=0.000), the proportion of overweight and obese students (P=0.012), students with elevated BP(P=0.008). A significant increase in physical activity was found among the intervention group in doing regular physical exercise (P=0.004). Conclusion: This school-based intervention program on a healthy lifestyle significantly decrease BMI, blood pressure and improve eating habits, physical activity among adolescents.