Treadmill is effective in burning the unwanted fat, because it gets your heart rate going. When the heart rate increases-your body is making use of fat or calories to keep moving. Be careful, and increase the speed gradually.
Note down your target heart rate- to know your heart rate, minus your age from 220. Now multiply this number by 0.6 and 0.9. The number you will get is the target heart rate you should look for. The best possible option is to buy a heart rate monitor which you can wear when using the treadmill or during other exercises.