Physical Development From Ages 13 to 19

During your teen years, your body will grow more than in any other period of your life besides infancy, according to KidsHealth online 3. This is because hormones suddenly produced by your pituitary gland will cause your child body to grow into a mature body. The transition can be rocky for many teens, but knowing that all teens go through the same changes might help you come to terms with your own developing body.

Puberty in Girls

Puberty typically begins between ages 8 and 13 in girls, which is earlier than it occurs in boys. Although girls often enter puberty around ages 10 and 11, most girls won’t menstruate until later. The average onset of menstruation occurs at age 12, but some girls won’t start until they are 16.5 years old, according to the Palo Alto Medical Foundation. Other changes in the female body during puberty include increased skin oil and acne, body odor, underarm and pubic hair, developed breasts, increased vaginal lubrication and increased body fat. Because puberty can last between two and five years, late bloomers might still be experiencing body changes such as breast development into their college years.

Puberty in Boys

Boys usually enter puberty between ages 10 and 15 and, like girls, might be fully developed two to five years after onset. Some enlargement of testicles, scrotum and penis typically precedes growth of hair on the pubis, underarms, arms, legs, chest and face. Nocturnal emissions (or “wet dreams”) are also common during puberty, occurring between ages 13 and 17, with an average age of about 14.5 years, according to Medline Plus Medical Encyclopedia. Boys will also notice increased oil production on the skin, muscle growth, body odor and a deepening voice.

Height and Weight

The average teen can expect to grow as much as 10 inches while going through puberty, according to KidsHealth online 3. Also, in a one-year growth spurt, both boys and girls might gain a much as 3.5 to 4.1 inches. Moreover, boys can expect to gain weight because of increased muscle development, and girls can expect to gain weight from increased body fat.

Assessing Height and Weight

Although many teens might feel awkward after gaining—or not gaining—noticeable amounts of weight during puberty, not all teens have weight issues. Body Mass Index (BMI) can be used to assess a teen’s body fat in a similar fashion as it does with adults, only teens’ bodies are consistently changing at such different rates that there are different charts for girls and boys younger than 20. Teens are also plotted on a chart and given a percentile to determine where they rank in context with people of the same age and sex. A teen below the fifth percentile, for example, might be considered underweight, and a teen in the 95th percentile might be considered obese.


Sudden changes in teen bodies can cause temporary changes in their behavior. For example, most teens sleep longer to accommodate rapid growth, according to the Virginia Cooperative Extension online 1. Also, clumsiness and insecurities might also develop as teens are learning how to adapt to and accept their changing bodies.