How Body Changes During Puberty

Puberty (यौवन) is what happens in children’s bodies that change them into adults. After puberty, people are able to make children. A girl who has gone through puberty can become pregnant and have a baby. At puberty, a boy’s body begins making sperm, and he starts to be able to ejaculate, which is semen coming out from his penis when he is sexually excited. If he has sexual intercourse with a girl, he can make her pregnant. Being the puberty period most important, Siddha Spirituality of Swami Hardas Life System thinks that every person should know about puberty so that they can take appropriate care and grow healthy for making life glorious.

Puberty definition

Puberty is the condition of being or the period of becoming first capable of reproducing sexually that is brought on by the production of sex hormones and the maturing of the reproductive organs, development of secondary sex characteristics (such as male facial hair growth and female breast development), and in humans and the higher primates by the first occurrence of menstruation in the female.

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Puberty in Boy & Girl

Puberty age 

Puberty is started by hormones, which are chemicals that tell parts of the body to do things. Today, on average, girls start puberty at age 10 or 11, and boys at age 11 or 12. However, people all over the world start puberty at different ages.

Because puberty is the time in a child’s life when he or she becomes able to make children, this is seen as very important. Therefore, people in many countries around the world have different ways of marking this event.

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Puberty Age Chart: Boys & Girls

How the body controls puberty

Puberty is started and carried on by different hormones. Hormones are chemicals that tell parts of the body to do things. Hormones are made by glands in the body. Glands are organs (special parts) of the body that make hormones.

This is what happens during puberty:

  • A gland at the bottom of the brain called the hypothalamus sends gonadotropin-releasing hormone into a nearby gland called the pituitary gland.
  • GnRH causes cells in the pituitary gland to make two hormones, Luteinizing Hormone, and Follicle Stimulating Hormone. LH and FSH are types of hormones called gonadotropins. The bloodstream carries these hormones around the body.
  • LH and FSH make the gonads grow larger and start producing their own hormones, Estradiol, and Testosterone. A girl’s gonads are her ovaries, and a boy’s gonads are his testicles. Both ovaries and testicles produce estradiol and testosterone, but ovaries produce more estradiol and testicles produce more testosterone. Estradiol and Testosterone are types of hormones called steroid hormones. Steroid hormones are also made by the body’s two adrenal glands, which sit on top of the two kidneys.
  • When the amount of estradiol and testosterone in the body increases, various parts of the body change.

When puberty starts and ends

On average, girls begin puberty at ages 10–11; boys at ages 11–12. Girls usually complete puberty by ages 15–17, while boys usually complete puberty by ages 16–17. The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12–13; for males, it is the first ejaculation, which occurs on average at age 13.


Genetics is the study of how parents pass on to their children some of the ways they are through their genes. Half of a person’s genes come from the mother. The other half come from the father. 


Boys and girls who have a good diet – who eat healthy food – tend to start puberty earlier. Today, people start puberty younger than in the 1840s.


Young people who exercise a lot, such as athletes and gymnasts, may start puberty later. It may also happen more slowly for them. This is thought to be because their bodies use up the food that they eat faster. This causes them to have less body fat, so there is less leptin to tell their brains to start puberty.


Obesity is the state of being very overweight. A scientific study seems to say that girls who are obese start puberty early. Some obese girls have started growing breasts before the age of nine years and have had their first period before 12 years. If a girl is obese, her body fat sends signals to her brain that she is ready to become pregnant. Girls who have early puberty can have health problems later on in life.


Boys and girls who are sick for a long time, especially with illnesses that cause them to have a poor diet, tend to start puberty late. For example, this often happens to people who suffer from anorexia nervosa. Anorexia nervosa, often called “anorexia” for short, is an eating disorder.


It is thought that people who are under a lot of stress start puberty later. Not many studies have been done to find out if stress also causes boys to start puberty later.


Some scientists think people may start puberty earlier because their bodies are affected by chemicals such as estrogens and progestagens that are put in the environment by humans. Another chemical that may cause early puberty is Bisphenol A (BPA). It is used to make plastics, such as some types of baby bottles, water bottles, and sports equipment.

Girls usually reach their adult height and become sexually mature (able to have babies) about four years after puberty starts. Boys keep growing for about six years after puberty starts. Puberty in boys starts off more slowly than in girls but then speeds up later on. 

How body changes during puberty in boys

For most boys, puberty takes about six years and ends when they are about 17 or 18 years old. At the end of puberty, a teenager is usually about 10 to 30 centimeters (4 to 12 inches) taller, 7 to 29 kilograms heavier, and stronger. He is also able to make a woman pregnant.

Sex organs grow bigger

The first sign of puberty in boys is that their testicles and scrotum (the bag that the testicles are in) grow bigger. Before puberty, each testicle is about 1.5 to 2 cm long and has a volume of about 2 to 3 cubic centimeters. About six years after puberty starts, the testicles reach their adult size. The volume of an average adult man’s testicle is about 18 to 20 cubic centimeters. However, it is normal for some men to have testicles smaller than this size, and for other men to have larger testicles.

The penis also grows bigger during puberty. At the start of puberty, the average length of the penis is 6 cm (2.4 inches). The penis reaches adult size about five years later. A study done in 1996 found the mean length of an adult man’s penis is 3.5 inches (8.9 cm) when it is flaccid (not erect or hard). The average length of an erect penis is about 12.9 to 15 cm (5.1 to 5.9 inches).

The testicles have two main jobs:

  • To make hormones, and
  • Sperm

The testicles make the hormone testosterone, which spreads around the body. This causes changes in the body that make a boy grow into a man. Testosterone also makes a man feel like having sex. One year after puberty begins, when boys urinate after waking up in the morning, some sperm can be found in the urine.

When a boy is about 13 years old his testicles will have grown to the stage that he may be fertile. However, it will still be difficult for him to do so. Boys usually only become fully fertile when they reach about 14 to 16 years of age.

The sperm in the testicles mixes with other liquids in the body to form a whitish or yellowish and sticky fluid called semen. During puberty, two glands in the body called the seminal vesicles and prostate also grow bigger. These glands make a lot of the liquid that is in semen.

When a man is sexually excited, he gets an erection – his penis becomes bigger, longer and harder. A male can become sexually excited if thinks about sex or sees a good-looking person, or if his penis rubs against something. During puberty, some boys also have spontaneous erections. These are erections that happen by themselves without any reason. This can be embarrassing when it happens in a public place.

When a man’s penis is sexually stimulated for some time, he has an orgasm and semen shoots out from the penis. This is called ejaculation. Boys who have not begun puberty cannot ejaculate. A boy’s first ejaculation usually happens about one year after he begins puberty.

For some boys, the first ejaculation takes place when they are sleeping. This is called a nocturnal emission or a wet dream. It happens without the boy’s control, often when he is having a dream about sex. Scientists believe that wet dreams are the body’s way of removing too much semen.

A male masturbates when he rubs his penis to make himself feel good sexually. The study also found that most boys who have their first ejaculation by masturbating do this a year or more earlier than boys who have their first ejaculation through a wet dream.

When a boy starts to ejaculate, he usually produces only a small amount of semen. The semen is different from what an adult man produces. It is usually clear and stays sticky. It either has no sperm in it or sperm that do not move properly or do not move at all. A boy’s semen only becomes like an adult man’s semen about two years after his first ejaculation.

Body hair and skin changes

Not long after a boy’s testicles and penis start to grow, pubic hair begins to appear. Pubic hair is hair that grows in the pubic region, which is the part of the body where the penis is. Pubic hair is shorter, curlier and rougher than the hair on the head.

It usually starts growing on the abdomen above the penis at the place where it joins the body. There may also be some hair on the scrotum. After about six months to a year, there will be a large triangle of hair in the pubic region. Within three to four years after puberty begins, there is a lot of pubic hair in the area above the penis. Later on, pubic hair also grows on the abdomen upwards towards the navel and on the insides of the thighs.

About two years after pubic hair starts to appear, the hair also grows on other parts of the body:

  • In the armpits
  • Around the anus
  • On the upper lip, forming a mustache
  • On the sides of the face in front of the ears, forming sideburns
  • Around the nipples
  • On the lower part of the face, forming a beard

The hair on the arms, legs, chest, abdomen, and back may also become thicker. Different men have different amounts of body hair. Many boys begin shaving when hair starts growing on their faces.

A larger amount of male hormones in the body cause changes to perspiration (sweat). This gives it a more “adult” body odor or smell.

The hormones also cause sebaceous glands in the skin to make more sebum, a type of oil that keeps the skin from getting too dry. Sebum and dead skin cells can mix with a type of germ called bacteria and block pores (tiny openings) in the skin. This causes a skin problem called acne.

Most people get acne during puberty. When a person has acne, he gets swellings on his skin called blackheads, whiteheads, and pimples. Blackheads and whiteheads are painless, but pimples can be red and painful. They usually form on the face but can also appear on the neck, shoulders, upper back, and chest.

Oil glands on the scalp – the part of the head on which hair grows – also make a lot of sebum. This can cause dandruff, in which small white bits of skin fall from the scalp.

Voice changes

During puberty, a boy’s larynx or voicebox also grows larger. This makes the laryngeal prominence or Adam’s apple – the lump that sticks out of the front of his neck – larger too. As the larynx grows the vocal folds become longer and thicker, so they vibrate (move back and forth) more slowly. This causes the voice to lower in pitch or tone and become deeper. 

Body growth

Towards the end of puberty, boys go through a growth spurt which lasts for about two to three years. During this time, their body grows taller very quickly. When the growth spurt is at its fastest point, some people grow 10 cm (4 inches) or more a year. This happens about two years after puberty starts, usually between the ages of 13 and 15.

When a boy reaches the end of his growth spurt when he is about 18 years old, he will be at his adult height. His body will not grow much taller after that. Because of their growth spurt, boys’ muscles can feel sore. These growing pains can feel worse if boys are active and do a lot of exercises. They go away after a while.

Boys grow more slowly than girls, but for a longer time. That is why most men are taller than women. By the end of puberty, adult males have heavier bones and more muscle than females. In an average adult man, muscle makes up 50% and fat 15% of his weight.

On the other hand, 40% of an average adult woman’s weight is made up of muscle while 27% is made up of fat. Because men have less body fat than women, their hips do not grow bigger. Some bones like those in the jaw and shoulders grow more in males than in females. That is why males have wider faces and shoulders but narrower hips.

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Body Changes During Puberty: Boys

How body changes during puberty in girls

The changes in a girl’s body during puberty usually take place between the ages of eight and 18 years. Most girls will have finished puberty around the age of 15. They will have breasts and pubic hair will menstruate (have a period) every month and will be able to get pregnant. They will usually also have reached their full adult height.

Breasts grow

When the breasts start to grow, this is normally the first sign of puberty that can be seen on the outside of a girl’s body. This usually happens when girls are about the age of 10.5 years.

A lump that is a bit hard appears in each breast under the areola, which is the dark ring around the nipple. The lump in one breast may grow before the other one. This is called breast budding.

Within six to 12 months, both breasts will have started growing. The swelling can be felt and seen outside the edges of the areolae. About one and a half to two years after the breasts first start growing, they are close to the shape and size of an adult woman’s breasts.

The nipple and areola may be on a smaller mound on each breast. This small mound usually goes away when each breast is fully grown. Whether the breasts are small or large depends on how much fat there is in the body.

Body hair and skin changes

Between the ages of about 8 and 14 (on average, at 11 or 12 years), pubic hair begins to grow along the labia (the lips of the vulva), usually a few months after the breasts start growing. At first, the hair is thin and straight instead of curly, and there is not much of it.

Within a year, the pubic hair becomes rough, dark and curly and grows in a triangle shape in the pubic region. About one year after pubic hair begins appearing, underarm hair also grows. The hair on the arms and legs also gets thicker, and some girls may have hair appearing on their upper lip and in front of their ears.

Like boys, higher amounts of hormones in the body cause girls’ perspiration (sweat) to change. This gives them a more adult body odor or smell. The hormones also cause the skin to produce more sebum (oil), which usually leads to acne.

Sex organs and menstruation

When girls are between eight and 11 years old, the two ovaries in their body begin to grow bigger. Each ovary is egg-shaped and is attached to the side wall of the pelvis. The pelvis is a large set of bones in the hips. The ovaries are organs that make female hormones.

These hormones cause a girl to grow into a woman and make her feel like a woman. The hormones also make it possible for females to become pregnant and have babies. Inside the ovaries are about 200,000 ova (egg cells). For a baby to be formed, a woman’s ovum and a man’s sperm must come together. During puberty, the ova also grow bigger.

Between the ages of 9 and 15 years (on average, at 12 to 13 years), the vagina and uterus become bigger. The uterus is the organ in which a baby grows. The vagina is a tube leading from the uterus to the outside of the body. The opening of the vagina is inside the vulva, in between the legs. A clear or whitish fluid may start to flow out of the vagina to keep it clean.

Then, about two years after the breasts start to grow, when a girl is between 10 and 16 years old (on average, at 13 to 14 years), hormones made by her ovaries cause the ovaries to release an ovum, which moves into the uterus. Usually, only one ovum is released at a time. The hormones also tell the uterus to get ready for a baby, in case the ovum meets sperm and gets fertilized. The walls of the uterus become thicker with extra tissue.

Inside the thick part of the uterus are blood vessels and other nutrients that a baby will need to grow. If an ovum in the uterus gets fertilized, it sticks to the wall of the uterus and starts to grow. However, if the ovum is not fertilized, it does not stick. The uterus then gets rid of the ovum and the extra tissue by releasing it from the body.

The tissue and blood flow out of the uterus through the vagina. This is called menstruation or having a period. The bleeding normally lasts for about three to five days, though some girls may bleed for longer or have a bit of bleeding between periods.

The uterus then starts preparing for another ovum. For most girls, the time between their periods is about one month. For about two years after menstruation starts, the time between periods is not always the same.

Some girls may skip a month, or have two periods close to each other. It is also normal to have cramps or to feel bloated in the abdomen during periods. When many girls start having periods, they begin using sanitary napkins or tampons to soak up the blood and tissue.

Body growth

Because of more hormones in the body, girls start to have more fat in their:

At the age of ten years, the average girl has 6% more body fat than the average boy, but by the end of puberty, the difference is nearly 50%. The fat makes sure that a baby growing inside a pregnant woman will have enough nutrients. Also, the bones in the pelvis move further apart to make room for a larger uterus and ovaries, and so there is space for a baby to grow in the uterus and to pass out of the body when it is born. 

Girls also experience a growth spurt during puberty. In the first year after puberty begins, they grow about 8 cm (3 inches). They grow even faster the next year or so, then the growth slows down and almost stops when they start menstruating. After a girl’s periods begin, she usually does not grow more than 5 cm (2 inches) taller.

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Body Changes During Puberty: Girls

Emotional changes in boys and girls

The large amounts of hormones in the bodies of boys and girls during puberty can also affect their emotions. Young people begin to be attracted by each other and thinking about what it is like to have sex. They are often worried about what other people think about them.

They can also feel an urge to do things that are dangerous, such as taking drugs or too many alcoholic drinks or smoking.

They sometimes want more independence – more power to decide things for themselves and can get angry when their parents do not allow them to do things.

The brains of teenagers are still growing, and it may take a while before they are mature enough to know how to make good choices about their lives. Therefore, it may be helpful for them to follow the advice of adults they trust, even if it does not make much sense to them at the time.

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Emotional Changes: Boys & Girls


Puberty is the most important event in everyone’s life. We have tried to know everything about puberty including social and emotional impact on life. In many parts of the world, puberty is even pride for the society to celebrate. I trust readers should also help us to make this article reach at your relatives, friends, and other well-wishers by sharing so that they too avail this opportunity to know about this precious subject and event of the life. It would help even parents to understand their children’s emotions properly, which can help them grow healthy.

The opinions expressed in this article are the personal opinions of the concerned site owners. Siddha Spirituality For Health is not responsible for the accuracy, completeness, suitability, or validity of any information on this article. However, it is advisable to consult a specialist in the concerned field before availing the benefits. Hence we do not assume any responsibility or liability for the same.



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