Hi Lavanya,
Running is an intense aerobic exercise. Compare to other aerobic exercises like walking, jogging etc. it burns more calories and hence seems easy way to lose weight. But since running is intense and straining activity so obviously one may not be able to do it for long time, where as low to moderate intensity activity can be sustained for longer time and thus net calories burned is comparably more in low to moderate intense exercises than intense aerobics exercises. Also studies have proved that moderate intensity exercises are much more beneficial in losing weight than the intense one.