This is the most common question for people who are trying to get slim and burn extra fat. To lose one pound of body fat you have to burn approximately 3500 calories. So if you want to lose a pound a week you have to do a cardio exercise that burns 500 calories per day (7X500 = 3500). If you want a day off then you have to do an aerobic exercise or cardio workout that burn 600 calories per day (6X600 = 3600) or if you want to enjoy your whole weekend you need to burn 700 cals / day (5X 700 = 3500).