Breasts are made up of mostly fatty tissue. With the absence of any muscle tissue in the breasts, it is not possible for exercise to directly affect the size of the breast. The benefit of exercise in reducing breast size is the reduction of fat. By burning calories and lowering your percentage of body fat, some women will experience a reduction in the size of their breasts.
Spot Weight Loss
While certain exercises concentrate on specific areas of the body, or specific muscle groups, no exercise can affect weight loss in a specific part of the body. As a general rule, weight loss is experienced throughout the body, not in a specific area. For this reason, a good overall exercise plan will reduce your body's fat content, but it will not specifically work on the breasts.
When attempting to lose weight, you will want to watch your diet and develop a good exercise routine. Your goal is to burn calories and increase muscle mass. There can be, of course, a big difference in the calories burnt by doing different exercises. A 155-pound person will burn 739 calories an hour on a stationary bike. That same person will burn 422 calories in an aerobics class, 281 calories by taking a brisk walk, or an amazing 844 calories per hour by skipping rope at a fast pace. Other good exercises are swimming, rowing and jogging. Which exercise you choose will depend on your personal preference and physical condition.
Other Effects of Exercise
While the breasts do not contain muscles, there are muscles in the chest that, when toned and conditioned, will tighten the chest area and can in some cases make the breasts appear smaller. Some exercises that concentrate on your chest are push-ups, bench presses and swimming. All of these can improve muscle tone and mass in the chest area and will affect the appearance of your breasts. While the appearance of your breasts may be altered, do not expect miracles. At best, most women can expect a reduction of one cup size or less as a result of increased exercise.