Growth and Physical Changes

In middle school and early high school, girls will generally be taller than boys. But, look around. There will be a few boys who are very tall, or who have deepened voices, and a few girls who still haven't started to mature physically. These differences can be hard on kids who wonder if they are normal or if they will ever catch up. Rest assured, these differences are normal. Everyone's growth rate is different but normal for them. Except for your first year of life, physical changes occur more rapidly during adolescence than at any other time. When and how quickly these changes occur is determined by many things from heredity, to diet, to the environment. During the last century, every generation has been taller than the preceding one. Both boys and girls are maturing earlier than their parents did. Unfortunately, more teen men and women are overweight than ever before.

Many of the physical changes you experience seem out of your control, and they are. But they are not mysterious changes if you understand what is happening, and that it is all a normal part of human growth. Remember that your parents are dealing with this too, and may be left wondering what happened to their baby. Just as you do, your parents have to adapt to the changes you are undergoing.

During the year of greatest growth, an adolescent boy may add 4 inches in height. Typically boys will grow an average of 8 inches during adolescence. Girls can expect to grow an average of 3 inches during the adolescent years. The rate of growth for girls slows after menstruation begins. So, boys tend to start growing later than girls but keep growing longer.

Boys often lose body fat as they grow while a girl's body will redistribute the fat. After peak growth, boys gain weight again and muscle mass increases for another year or more after full height is reached. From the beginning to end of puberty, boys will have gained an average of 40 pounds and girls will have gained 25 pounds.

As you grow, both your legs and body trunk will lengthen. Your lower jaw will grow changing your facial appearance. Internal organs such as your heart, liver, kidneys, and digestive tract grow during adolescence as well. Sweat glands have developed and this is the age when you should have started to use deodorant-if not start now!

For boys, the larynx or voice box, becomes larger. While the larynx is growing the boy's voice may "crack". Once the larynx has finished growing, the boy's voice becomes lower and deepens. Boys begin to grow pubic hair, hair in the armpits (axillae), on legs and arms, and may have the beginning of a mustache on the upper lip. Girls also grow pubic hair and hair in the armpits, but for girls, hair grows on the arms and legs to a lesser extent than for boys. It is normal for this hair to be darker than the hair on your head.

Adolescence is a time of rapid changes in the reproductive tract as well. The term puberty is used to describe the period of time when your reproductive system matures and physical changes occur that differentiate boys from girls.

For girls, the female hormone estrogen plays a role as breast development occurs, the vagina and ovaries grow and girls start to menstruate. Early periods are often not regular, but will become more predictable as you grow older. Generally, periods should be occurring at predictable intervals within two years of your first period. Either pads or tampons are fine to use, depending on your personal preference. Having your period should not interrupt your life-stick to your normal activity level. Girls should have their first pelvic exam when they are sexually active, have abnormal vaginal bleeding or discharge or have severe pain with their periods.

For boys, reproductive maturity brings growth of the penis and testicles. It is normal for one testicle to be slightly larger than the other or to hang lower than the other. There is a wide variation in penis size and male sexual functioning is not dependent on the size of the penis. The male hormone, testosterone, is responsible for muscle growth, gain in body size, body and facial hair and other male characteristics. Sometimes boys develop a small amount of breast tissue at the onset of puberty, this is normal and resolves with time.

During this time it is normal to want more privacy. Most adolescents are fascinated by the changes occurring within their bodies, but also wonder if they are normal. This is a time emotionally, when you may want to be like everyone else, but teenagers need to be aware that being like everyone else means you all develop on your own schedule.

If you have real concerns about how you are growing, be sure to talk to your doctor. We also have brochures and more information on many of these subjects. Feel free to talk to us about any of these topics.

What about my brain?

From about 13 to 25 your brain goes through a major wave of growth from back to front.

The front part of your brain is the Prefrontal Cortex. It is like the boss of your brain. It is responsible for impulse control and making choices based on logic. It kind of goes on vacation for a bit while the back and middle parts take over.

The Cerebellum is in the back of the brain and it controls coordination and makes you want to move. It's all about how well you type on a computer keyboard or throw a ball. The Cerebellum kicks off the whole process of growth from back to front.

The midbrain is all about emotion and reward. It likes to mix things up a bit. Your brain is responding to other people and situations in new ways. This can mean you might misread signals like facial expressions or tone of voice, or overrespond emotionally in some situations.

The reward part of the midbrain means that you may prefer high excitement, low effort activities. (The video game companies count on this!) When the midbrain becomes more dominant than the front of your brain, risk-taking, reward, and pleasure seeking begin to play a role in your behaviors.
The boss or "CEO" of your brain (the Prefrontal Cortex) makes choices based on facts and can help control impulses. The tricky art can be that when you need your boss the most, it might not be up to the job. Remember, it finishes growing last when you're around 25 or so. The good news is, your brain grows stronger and gets more on the job experience every day!

Your brain is like wet cement right now

Your brain is a bit like wet cement because it is flexible and open at this time. You have to be careful because some things learned can become fairly permanent or 'set'. This can be good or bad.

  • The more brain connections work together, the stronger they become. This makes sense when you think about the old saying "practice makes perfect" or "use it or lose it".
  • Playing a sport, dancing, reading, playing music, playing video games, drawing or watching TV reinforces the brain connections you are using when you do the activity. What you do matters!
  • And of course the connections you use the least, fade away.
  • The big danger with the brain being so open at this age is that the use of alcohol and other drugs can quickly lead to addiction. Addiction is basically the brain "over-learning".       (For example: A 13-year-old has a 43% chance of developing alcohol addiction. At age 21 the risk drops to 10%. If someone in the family is an alcoholic however, the risk can be double due to genetic make-up)

    It is important to know that all this brain stuff might start to happen at about the same time as puberty. So for a while lots of things could be happening at once.

    Even though everyone is different, you might notice:

    • Sometimes having trouble holding back or controlling emotions
    • Having different sleep patterns/wanting to stay up late (the brain does this for a while, but you can train it)
    • Liking excitement and low effort activities (video games)
    • Being overly concerned about what other people think of you
    • Not considering possible negative consequences of your actions