A cross sectional study of 888 randomly selected subjects in Shimla town was done to determine prevalence of obesity, its relation to age and physical activity. The prevalence of obesity was 21.5% using cut off levels of BMI 25. The prevalence of obesity rose significantly with age. Obesity was less in those having moderate physical activity as compared to those with low and high activity. Primary prevention is required to tackle this disease risk factor through health education focussing on promotion of moderate regular physical activity.