Regular cardio workouts can burn fat and help to reduce breast size.
Chest exercises alone will not make your breasts smaller. These exercises serve to strengthen your pectoral muscles, or the muscles just beneath your breasts, lifting your bustline and making your breasts appear larger. According to Mark Vella's book "Anatomy for Strength and Fitness Training for Women," chest exercises can boost chest size but not cup size. You can shed excess weight and reduce breast size by following a cardio regimen and nutritional plan that results in a calorie deficit.
Lift and Tone
A training regimen for your chest can include bodyweight exercises, such as pushups and dips, as well as various resistance exercises -- presses, flies and crossovers -- using free weights, cable machines or elastic bands. These exercises tone your pectorals and can make your breasts appear perkier. For example, begin a bench press by lying supine on a bench with knees bent and feet flat on the floor. Hold 2- to 5-pound dumbbells with a neutral grip, palms facing each other. Position the weights next to your shoulders with elbows bent just below your shoulders. Exhale and slowly lift the weight up and over your chest, fully extending your arms. On the way up, slowly rotate your wrists inward until your palms face your head at the peak position. Reverse the motion to return to starting position. Perform eight reps for three sets.
Cardio to Resize
If you aim to reduce your breast size with the help of exercise, engage in cardio workouts of sufficient duration to burn fat. Aerobic activities can include cycling, rowing, walking, jogging or swimming. Also, you can choose among several machines at the gym, such as the treadmill, elliptical trainer and stair-climber - with preprogrammed cardio session. To lose a pound of fat per week, you'll need to burn 3,500 calories, which translates into a 500-calorie deficit per day, according to the American Council on Exercise. If you burn about 560 calories per hour of aerobic exercise performed at 60 to 70 percent of your maximum heart rate, you'll need five one-hour workouts per week. Increasing the number of workouts to six or seven will allow you to slightly reduce the duration of your cardio sessions.
Intervals for the Time-Starved
High-intensity interval training is a more efficient way to burn fat and reduce breast size but requires a higher level of fitness. By boosting the intensity of your cardio training, such as cycling or running, to as much as 85 percent of your maximum heart rate and performing the exercise in intervals, you can increase your metabolism as well as benefit from afterburn, or excess-post exercise oxygen consumption. In addition, interval training takes about 30 minutes, or about half the time of a cardio endurance workout. For example, begin pedaling a stationary bicycle for two to three minutes at a low intensity to warm up. Increase the resistance to 4 or 5 and pedal as fast as you can for 30 seconds. Shift the resistance to its lowest setting and pedal for 60 seconds. Beginners can extend this active rest period for 90 to 120 seconds. Repeat this interval for 20 to 25 minutes and then do two or three minutes of cool-down cycling to wrap up the session.
Think Raw and Natural
If you aim to reduce your breast size without surgery, follow a balanced diet consisting primarily of natural foods, such as fruits, vegetables and whole grains, as well as lean protein. Avoid processed food such as products with refined sugar and simple carbohydrates. Foods rich in vitamin B -- eggs, lentils, bananas and oats -- will help you maintain energy while you pursue a fitness regimen. Lower your intake of salt to minimize fluid retention and bloating, which can lead to swollen breasts. Drink plenty of water.