According to MedlinePlus, doing activities such as brisk walking, biking or dancing burns 370 to 460 calories per hour. Doing such activities for 20 minutes for two weeks burns 1,726 to 2,146 calories, which may potentially translate to losing about 0.5 pounds.
Mayo Clinic states that burning 3,500 calories results in losing 1 pound if you burn more calories than what you get from eating. MedlinePlus recommends exercising for at least 150 minutes per week. It is not necessary to complete the total daily exercise all at once. Breaking it up into shorter time periods of 10 or 20 minutes likewise achieves the desired results.