Why is physical activity important in weight loss?

Physical activity helps to burn calories. A person will lose weight when he/she burns more calories than he/she takes in, so physical activity, such as walking, jogging, Bowling, playing tennis, etc., is a good way to burn extra calories. On the other hand, if a person is trying to gain weight, either more food should be eaten, or physical activity should be scaled back a bit so that more calories are taken in than are being burned.