Physical Changes in Adolescence and Puberty

Adolescence is a stage in which young people undergo physical, psychological and social changes. These allow the adolescent to mature and become an adult. What is the difference between puberty and adolescence? Let’s look at the most significant physical changes of adolescence in boys and girls.

1. Increase in height

If you have a son or a daughter, you will quickly notice how they progressively increase in size; This is one of the most common changes during puberty. The peak in girls is between 12-13 years old and in boys between 14-15 years old . The earlier the age of onset of puberty, the greater the increase in height.
Growth occurs in phases : initially the lower limbs grow and then the trunk, arms and head. This can lead to a feeling of disproportion that translates into insecurity in the adolescent.
When the epiphyses of the bones are closed by hormonal action, the end of growth is marked, giving rise to the final size . The final size is reached between 16-17 years in girls and can be delayed until 21 years in boys.

2. Body changes and organ development

There is an increase in the size of the organs (heart, lungs, spleen, kidneys …) but also, there is an increase in muscle mass and bone density and body fat is redistributed:

  • Girls have pelvis enlarged and accumulate more fat than boys . In adulthood, women have a% fat that is between 18-22%
  • Boys have broader shoulders and experience greater bone and muscle growth than girls. In adulthood, men have a% fat that is between 12-16%.

3. Increase in bone mass (mo)

Each individual has a genetic potential to develop OM, which is only fully achieved if environmental factors such as physical activity and nutrition with calcium intake are optimal.

4. Sexual maturation

The most striking changes take place in the sexual sphere and culminate in the acquisition of fertility . The sexual maturation index is medically assessed using the so-called “ Tanner stages ” and is based on the description of the development of the sexual organs and secondary sexual characteristics (markers of femininity and masculinity).

Hormones and physical changes in adolescence

Female hormones

The secretion of the hormones FSH and LH stimulate the maturation of the ovaries and activate them to produce other hormones: estrogens and progesterone. With all these physical changes in girls ovulation and menstrual cycle are induced.

  • Estrogens, like estradiol, stimulate the development of the breast, the external genitalia, and the uterus.
  • Progesterone has a role in the maturation of the endometrium and the breasts.
  • There is also an increase in testosterone that stimulates growth, as well as the development of pubic and armpit hair.

The menarche ( first menstruation ) usually occur about two years after telarquia (breast appearance button). The best reference about its onset is the age of menarche in the mother and in the sisters. Height gain after menarche is variable, averaging 7 cm. The breasts and the external and internal sexual organs grow and the pubic and armpit hair develop, the voice also changes and the body odor increases.

Male hormones

A 4 ml volume of the testes marks pubertal onset. It usually happens about two years later than in girls and therefore they can appear more physically mature at the same age.

  • In boys, the secretion of the hormone FSH stimulates the formation of sperm.
  • The hormone LH stimulates the cells of the testicle to form testosterone and this accelerates the growth of the child, matures the genitals (penis, scrotum and prostate), stimulates the growth of pubic, facial and armpit hair, changes the voice and increases libido.

Difference between puberty and adolescence


It is a biological process in which numerous physical changes take place. The onset of normal puberty is considered the appearance of thelarche (breast button) between 8-13 years in girls and an increase in testicular size , as well as redness and roughness of the scrotal sac between 9-14 years in boys .
The onset of puberty depends on several factors such as genetics, diet, race, geographic location or mental and social stimuli. Although, in recent years, thanks to the increase in quality of life, health and nutrition, we are witnessing an advancement of the age of adolescence, for example, in the case of girls, it is increasingly common for them to have their first menstruation at a fairly young age.


It is the period of transit between childhood and adulthood and means a broader concept that encompasses physical, psychosocial and emotional changes . The American Society for Adolescent Health and Medicine places this stage between 10 and 21 years.
Adolescence begins with the beginning of puberty and the end of this stage is not clearly delimited since there is a wide variability in the different aspects of development. In this stage, we go from concrete to abstract thinking, moral development occurs (knowing what is right and what is wrong) and impulse control and awareness of body image (acceptance of the body, sexual identity and the self).
It is very important to know all the stages of growth and development of the child for when he is in the period of puberty, offer him more understanding, confidence and patience. At the end of the day, this is a process that we have all gone through and at that moment, everything seems much more complicated than it really is.

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