Puberty causes changes in the shape and feeling of your body. "Man boobs" on a 13-year-old boy may be an effect of having too much body fat, but they can also develop as a result of hormonal shifts occurring during puberty. This growth of breast tissue in a teenage guy is known as gynecomastia 1. It's totally normal and usually temporary. Whether they appear due to an unhealthy body size or because of hormones, exercise and a quality diet will help you manage your body as it changes during your teenage years.

Causes of Enlarged Breast Tissue in Boys

If you're overweight and spend more time playing video games than being active, you may develop extra fat tissue in your chest that resembles small, low-hanging breasts. The more processed food and soda you consume, the more likely it is for you to pile on the pounds -- even as a teen. A study of Chinese adolescents published in Asia Pacific Journal of Clinical Nutrition in 2010 found that overweight and obese teens tended to consume soda and energy-dense fast food in excess 2. The excess fat in your chest is not directly related to hormonal changes, it's known as pseudogynecomastia.

If you're not notably overweight, your chest may just be another one of the changes -- such as a deeper voice and longer penis -- you experience during puberty. Although boys usually produce mostly androgens, a small amount of estrogen is also present. Some guys produce more estrogen than others -- enough to spur the temporary development of a mild amount of breast tissue and accompanying soreness. This condition doesn't last, it's just your body's way to adjust hormone levels as you grow.

Your doctor can help you determine whether you are at an unhealthy weight resulting in pseudogynecomastia or experiencing hormonal gynecomastia 1.

Achieving a Healthy Body Weight at 13

If your doctor suggests you lose weight to address your health and self-consciousness about your chest, you'll need to adjust your diet. As a 13-year-old boy, you don't want to significantly restrict calories because this can lead to nutrient deficiencies that interfere with growth. You need protein for muscle development, healthy fats to support your brain and calcium to build strong bones, for example.

Snack on fresh fruit, yogurt, nuts or whole-wheat crackers and low-fat cheese.

Exercise Importance During Puberty

You need at least one hour of physical activity each day to maintain a healthy weight, support your energy and keep a positive mind-set. Limit screen time so you can spend more time moving -- whether that's skateboarding, riding a bike, playing sports or walking your dog. Some of those weekly hours should be spent strengthening muscles too. Do this with pushups and pullups, hanging out on a playground, practicing martial arts or with adult-supervised weight training at a fitness center.

Meeting or exceeding the one-hour-per-day physical activity recommendations helps you burn calories so that you lose weight. Losing weight by being more active won't jeopardize your nutritional intake and essential growth either.

Gynecomastia Solutions

If you have breast growth due to puberty's erratic hormones, there's little you can do. Gynecomastia affects about half of pubescent young men and usually resolves on its own within a few months or a couple of years 1. Loosely fitting shirts may help you feel less self-conscious. If you find the condition exceptionally disturbing, talk to your doctor about medical options.

Certain medications, use of illegal anabolic steroids and some diseases can also cause the condition. Illicit drugs, such as marijuana and heroin, sometimes cause hormonal disruption that results in gynecomastia, too 1.