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Teen Growth and Development


Adolescence is a time of many transitions for teens and their families. To ensure that teens and adults navigate these transitions successfully, it is important for everyone to understand:

  • What is happening to the teen physically, cognitively, and socially?
  • How these transitions affect teens?
  • What adults can do?
  • What support resources are available?

Physical Development

What is it?

During the teen years, adolescents grow faster than they have at any time since they were infants. Physical development includes:

  • Rapid gains in height and weight. During a one-year growth spurt, boys and girls can gain an average of 4.1 inches and 3.5 inches in height respectively. This spurt typically occurs two years earlier for girls than for boys. Weight gain results from increased muscle development in boys and body fat in girls.
  • Development of secondary sex characteristics. During puberty, changing hormonal levels play a role in activating the development of secondary sex characteristics. These include:
    • (1) growth of pubic hair;
    • (2) menarche (first menstrual period for girls) or penis growth (for boys);
      (3) voice changes (for boys);
    • (4) growth of underarm hair;
    • (5) facial hair growth (for boys); and
    • (6) increased production of oil, increased sweat gland activity, and the beginning of acne.
  • Continued brain development. Teens’ brains are not completely developed until late in adolescence. Studies suggest that the connections between neurons affecting emotional, physical and  mental abilities are incomplete. This could explain why some teens seem to have trouble controlling their emotions, impulses and judgments.

How do these changes affect teens?

  • Teens frequently sleep longer. Research suggests that teens actually need more sleep to allow their bodies to do the internal work required for such rapid growth. On average, teens need about 9 ½ hours of sleep a night.
  • Teens may be clumsier because of growth spurts. If it seems to you that teens’ bodies are all arms and legs, then you may be right! During this phase of development, body parts don’t all grow at the same rate. This can lead to clumsiness as the teen tries to cope with limbs that seem to have grown overnight. Teens can appear gangly and uncoordinated.
  • Teenage girls may become overly sensitive about their weight. This concern arises because of the rapid weight gain associated with puberty. Sixty percent of adolescent girls report that they are trying to lose weight. A small percentage of adolescent girls (1-3%) become so obsessed with their weight that they develop severe eating disorders such as anorexia nervosa or bulimia. Anorexia nervosa refers to starvation; bulimia refers to binge eating and vomiting.
  • Teens may be concerned because they are not physically developing at the same rate as their peers. Teens may be more developed than their peers (”early-maturers”) or less developed than their peers (“late-maturers”). Being out of developmental “step” with peers is a concern to adolescents because most just want to fit in. Early maturation affects boys and girls differently. Research suggests that early maturing boys tend to be more popular with peers and hold more leadership positions. Adults often assume that early maturing boys are cognitively mature as well. This can lead to overly high expectations about a young person’s ability to take on increased responsibility. Because of their  physical appearance, early maturing girls are more likely to experience pressure to become involved in dating relationships with older boys before they are emotionally ready. Early maturing girls tend to suffer more from depression, eating disorders, and anxiety.
  • Teens may feel awkward about demonstrating affection to the opposite sex parent. As they develop physically, teens are beginning to rethink their interactions with the opposite sex. An adolescent girl who used to hug and kiss her dad when he returned home from work may now shy away. A boy who used to kiss his mother good night may now wave to her on his way to bed.
  • Teens may ask more direct questions about sex. At this stage, adolescents are trying to figure out their sexual values. Teens often equate intimacy with sex. Rather than exploring a deep emotional attachment first, teens tend to assume that if they engage in the physical act, the emotional attachment will follow. They may want to know how to abstain without becoming embarrassed or how they will know when the time is right. They may also have specific questions about methods of birth control and protection from sexually transmitted diseases.
  • When they are in their rooms, teens may begin to lock their bedroom doors. Locking doors is a way to establish privacy. As long as teens continue to interact with the family, locked doors are usually nothing to worry about.
  • Teens may not want to be seen with parents in public. They may ask parents to drop them off a block from their friends’ houses or from school.

What Can You Do?

Knowing what changes and behaviors are normal during adolescence can go a long way in helping both teens and adults manage the transition successfully. There are also some specific things adults can do to be supportive:

  • Don’t criticize or compare teens to others. Teens are already acutely self conscious about the way they look. They don’t need you to point it out to them.
  • Encourage teens to get enough sleep. Realize they may need an extra boost in getting out of bed for school. Try to understand when teens want to sleep until noon on Saturday.
  • Encourage and model healthy eating habits. Keep plenty of nutritious foods in the house. Remember that teens need to take in more calories to fuel their growth. Monitor eating habits accordingly.
  • Encourage and model physical activity. Exercise will help teens burn excess energy, strengthen developing muscles, — and they will sleep better at night. It may also help teens  become more comfortable in their changing bodies.
  • Provide honest answers to teens about sex. Teens are in search of knowledge. If adults do not provide accurate information, teens are forced to rely on their peers or other  potentially inaccurate sources. Unfortunately, incorrect information is often to blame when teens make poor decisions.
  • Be understanding of their need for physical space. Do not take it personally if your teen is not as physically affectionate as he or she was in the past. Do not force your teen to hug or kiss relatives or family friends. Maintain  communication, but respect teens’ need to withdraw.
  • Be patient with excessive grooming habits. Teens often spend large amounts of time grooming themselves and obsessing over skin care products. Often, this behavior merely reflects teens’ attempts to maintain some sense of control over their rapidly changing bodies.
  • Continue to provide a structured environment. Teens should be allowed to have more independence, but not enough to place them in jeopardy. Despite their complaints, teens rely on adults to provide them with the sense of safety and structure they need to deal effectively with all the developmental tasks of adolescence.


Pat Tanner Nelson, Ed.D.
Extension Family & Human Development Specialist

Adapted from information prepared by Angela Huebner, Extension Specialist, Family and Child Development, Virginia Tech

Suggested citation: Huebner, A. Teen growth and development in Nelson. P.T. (Ed) (2012) Families Matter! A Series for Parents of School -Age Youth. Newark, DE: Cooperative Extension, University of Delaware.


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