Answer:
It depends how much you are eating and how hard you are working out. If you are eating enough to maintain your current weight without the workout, then you need to burn off about 3500 extra calories to lose 1 pound (32000 kJ to lose 1 kg). For example, if you are not over-eating and you do step aerobics for an hour a day and you weigh 100kg, you could expect to lose a pound in a little under a week.