Yes, you can lose weight by walking! This table shows how many calories you burn (based on your weight) at a 3.0mph walking pace. Get a pedometer and try to shoot for 10,000 steps a day, roughly 5 miles. See how many calories you burn!
To take off 1 pound per week, you need to create a deficit of 500 calories per day. You can do this by eating 250 fewer calories a day (for example, cut out a 20-ounce bottle of regular soda) and burning an extra 250 calories through physical activity (for example, walk for 2.5 miles)