Exercise and good nutrition work together to keep you healthy. Regular physical activity helps control your appetite and burns off calories to help lose extra pounds or maintain a healthy weight. You need to burn off 3,500 calories more than you take in to lose one pound. If you want to lose weight, regular physical activity can help you in either of two ways. First you can eat your normal amount of calories but be more active. For example a 200 pound person can keep eating the same amount of calories but decide to walk 1½ miles briskly every day. This will result in a weight loss of about 14 pounds in one year. Or second, the person could take the same brisk walk AND reduce the calories eaten every day and lose an extra 26 pounds in the year.