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Your Teen’s Changing Body


two teen boys hanging out


The period between childhood and young adulthood is a period of rapid change - physical, emotional, cognitive and social. During this time, children’s bodies change in different ways at different times. No two teenage bodies are the same.

Physical changes during adolescence

For girls, you might start to see early physical changes from about 10 or 11 years, but they might start as young as 8 years or as old as 13 years. Physical changes around puberty include:

  • breast development
  • changes in body shape and height
  • growth of pubic and body hair
  • the start of periods (menstruation).

For boys, physical changes usually start around 11 or 12 years, but they might start as young as 9 years or as old as 14 years. Physical changes include:

  • growth of the penis and testes (testicles)
  • changes in body shape and height
  • erections with ejaculation
  • growth of body and facial hair
  • changes to voice.

Did you know?
Young people start to show physical changes at widely varying times. But if you’re worried about your child’s development, speak to a health professional.

Other physical changes: inside and out

Your child’s body is maturing physically, but brain development, thinking skills and emotional development are happening at their own speeds. What you see on the surface doesn’t always match what’s happening on the inside.

Adolescence is an important time for your child’s brain development. Changes in the teenage brain affect your child’s behaviour and social skills. So your child will begin to develop improved self-control and skills in planning, problem-solving and decision-making. This process will continue into your child’s early 20s.

Bones, organs and body systems
Many of your child’s organs will change in size and capacity. Lung performance improves, limbs grow, and bones increase in thickness and volume. The chest and shoulders get broader in boys. In girls, the hips and pelvis get wider.

Clumsiness and coordination
Because children grow so fast during this period, their centres of gravity change and their brains might take a while to adjust. This might affect your child’s balance. You might see a bit more clumsiness or poor coordination for a while, and your child’s chances of injury might also increase during this time.

Physical strength and sports skills
Muscle strength and size increase during this period. Your child’s hand–eye coordination will continue to improve over time, along with motor skills such as ball-catching and throwing.

Did you know?
Boys and girls who develop very early or very late might feel more self-conscious, get teased and have body image concerns. Girls often reduce physical activity, despite improved strength, because of body image and gender-based self-image concerns. Boys who have early physical development will have an earlier growth spurt. They might be bigger and stronger than their peers for a while. Boys who develop later might be more at risk of being teased or bullied, and might be less interested in physical activity. Remind your boy that strength and height aren’t important for all activities. Encourage other interests, not just sports that demand height and strength.

Nutrition and weight
Your child will gain weight and develop new nutritional needs. Teens’ stomachs and intestines increase in size, and they need an increase in energy, proteins and minerals. Foods with plenty of calcium and iron are particularly important at this age to support bone growth and blood circulation.

Sleep and rest
Sleep patterns change, with many children starting to stay awake later at night and then sleeping until later in the day. Also, the brain re-sets the body clock during puberty. Children going through puberty need more sleep than they did just before puberty started.

Sweat glands in the armpits and groin area are activated for the first time during puberty, and this can lead to increased body odour. Encourage your child to wash daily and wash clothes regularly. Using an antiperspirant deodorant can also help.

Acne and skin problems
Glands in the skin on the face, shoulders and back start to become more active during puberty, producing more oil. This can lead to skin conditions such as pimples and acne. If you’re concerned about your child’s skin, first check whether the pimples or acne are worrying your child too. If they are, consider speaking with your doctor.

Teens might find their hair gets oilier, and they need to wash it more. This is normal. Your child might like to change to a shampoo for oily hair.

Dental care
Children will gain their second molars at around 13 years. Third molars - “wisdom teeth” - might appear between 14 and 25 years. These teeth can appear in singles, pairs, as a full set of four wisdom teeth - or not at all. Not everyone has wisdom teeth. Encourage your child to brush twice a day and floss once a day.

Supporting your child through physical changes

Teens are adjusting to their changing bodies, which might make them self-conscious or embarrassed at times. They also compare their bodies with friends and siblings. Children whose development seems to be taking a long time compared to friends might seem frustrated or emotional.

You, or another appropriate adult, can help by:

  • providing support, reassurance and matter-of-fact explanations of physical changes
  • reinforcing that physical changes are different for every child
  • avoiding words like ”right” or “wrong” when it comes to development
  • not comparing your child to others.

Here are some more ideas and strategies for helping your child through the changes.

Be a healthy role model
Use every opportunity to be a healthy role model for your child and your child’s body image and attitude. It can be helpful to reinforce that bodies come in all shapes and sizes. Avoid comparing your child’s body to other people’s.

Treat your child in an age-appropriate way
On the outside, your child might have a mature body. Inside, your child might not have developed the self-control and thinking skills of a grown-up. At times, your child might act very grown up and at other times might seem more childlike and dependent on you.

With these sorts of mismatches, it can be hard not to treat your child as an older person. Keep in mind your child’s real age, and ask only for behaviour and a level of responsibility that’s appropriate for this age group.

Encourage healthy eating
Your child is likely to have an increased appetite and need more food. You can best meet your child’s teenage nutritional needs by:

  • providing healthy foods and drinks at home
  • encouraging healthy choices when you’re out
  • eating healthily yourself.

Support your child’s physical activity
Healthy physical activity habits set up in childhood and adolescence are often carried into adulthood. You can keep your child active by encouraging daily movement and involvement in team and individual outdoor and indoor interests. Try to be active yourself - for example, you could try walking rather than driving for short trips.

Encourage healthy sleep routines
Teens need enough sleep and rest. Lack of sleep or poor-quality sleep can have a big impact on thinking skills, concentration and performance at school. You can help by:

  • reinforcing a regular bedtime
  • encouraging “winding down” before bedtime – try no screen time at least an hour before bedtime and avoid high-sugar foods and caffeinated drinks
  • making sure your child has a quiet, comfortable sleeping environment, and encouraging your child to turn off the mobile phone.

You can read more about good sleep habits and tips for promoting good sleep.

Help your child with dental care
This is a good time for your dentist to check the position of your child’s teeth. You can reinforce the importance of regular dental checkups and of regular brushing and flossing. If your child plays contact sports, speak with your dentist about mouthguards to protect against possible sporting injuries.

Getting help

Every child experiences physical changes at a different rate. If you’re concerned about your child’s rate of development or about the way your child’s body is changing, talk to a health professional.

© Raising Children Network Limited, reproduced with permission.

Resources & Links:

HealthLink BC: Growth and Development, Ages 15-18 years

Last Updated: November 30, 2014