A 180 pound person would need to walk three miles over the course of an hour every day for three months to burn 10 pounds worth of calories, according to calculations from the University of Maryland Medical System. Walking at a faster pace can burn more calories.
People lose weight when the amount of calories they burn exceeds the amount of calories they consume, the Mayo Clinic reports. A pound of fat, for example, is comprised of 3,500 calories. Aerobic activity, strength training and the body's base metabolism determine the total amount of calories someone will burn day-to-day. Mayo Clinic notes that diet generally has more impact on people's weight than exercise.