Do you want to lose weight is the best way to get results from your workouts to exercise with it your ideal fat burning pulse rate (It tells the correct number of heartbeats per minute). If your heart rate goes over this, your body will need more energy than it's able to make by burning your fat and it will begin to burn muscle that is much easier and more energy.
To find your ideal fat burning pulse, you only need to specify age and the calculator gives you the maximum heart rate you should have when you exercise and want to burn fat.