Teen Physical Development

The teenage years are accompanied by changes in the body. Perhaps the most profound changes are linked to sexual maturation. It is during the teen years that the body grows into a sexually mature entity, and there are many distinct physical characteristics that develop as a result of this growth. Additional physical changes include rapid growth in height and weight, as well as continued developments in the physical make-up of the brain (1).

Sexual development

The changes associated with sexual maturation are among the most exciting and the most confusing for teens. Because of the hormones that are released sometime between the ages of 8 and 13, the body feels different – and soon begins to look different as well. While the period of sexual development (puberty) usually begins between the ages of 8 and 13 (2), it is not unusual for the changes to develop over a period of years. Most bodies, however, are developed by the age of 16, although everyone’s rate of development is different.

Substantial differences between girls and boys appear during the teen years. While both boys and girls grow pubic and underarm hair, and get acne due to increased skin oils, just about everything else that happens during teenage physical development differs according to gender (2).

Teen girls developments are often very visible, and a source of anxiety as well as anticipation:

  • Breast development
  • Hips become rounded
  • Female reproductive system components (uterus, vagina, labia, clitoris) increase in size
  • Menstruation begins

Teen boys also experience profound changes that affect their bodies, and often self-image:

  • Facial hair growth
  • Increased size of penis and testicles
  • Sperm production
  • Enlarged Adam’s apple
  • Voice changes

Increased height and weight

The teen years are the time in which height and weight increase at a rapid rate. Added height is, on average, 3.5 inches for girls and 4.1 inches for boys (1). Additionally, boys put on muscle weight while girls put on weight due to body fat. This can cause anxiety in many girls, who feel pressure to be thin. However, a certain amount of body fat, about 16% to 23% (3) is healthy for teenage girls. These changes can result in clumsiness, as different parts of the body grow at different rates, making it difficult to cope with the changing lengths of arms and legs (1). More sleep is also usually needed so that growth proceeds at a good rate, and so that the body receives the rest it needs. 9 1/2 hours of sleep each night is recommended (1).

Physical make-up of the brain

A teenager’s brain is still developing. It is not until the early 20s that the brain reaches its full development. Neuron connections are still forming during the teen years, and this can lead to emotional and mental lapses in judgment. Additionally, the developing brain contributes to impulsivity (1). Learning to control impulses, emotions and judgment is part of a teen’s physical brain development.

Helping teens through physical changes

Proper nutrition and exercise can help teens feel better about themselves and about their changing bodies. It is important to fuel the body’s physical changes with good foods and to encourage its healthy development with physical activity. Healthy sleeping habits should be encouraged. Additionally, it is important to help teens properly understand the sexual changes in their bodies. Honesty and education are important aspects of helping them understand teenage bodies in order to make healthy sexual decisions. Emotional support, that does not compare teens to their peers, is also important (1). Everyone develops at a different pace, and each teen should be aware that his or her pace is normal and appropriate for his or her own body.


  1. ext.vt.edu/pubs/family/350-850/350-850.html
  2. kidshealth.org/parent/growth/growth/growth_13_to_18.html
  3. girlshealth.gov/nutrition/bmi_calc.cfm