Cardio is crucial for keeping your metabolism running smoothly. In one study, researchers found that after a tough 45-minute cycling workout the subjects slashed 190 calories above their resting metabolic rate for 14 hours after their workout! According to the study author Dr. David Nieman, a professor of exercise science at Appalachian State University, "If you do just two to three vigorous bouts of exercise per week for 45 minutes, you could lose a pound of fat every two weeks from the combination of calories expended during exercise plus what you burn afterward."