As children grow, one of the essential rites of passage that they all go through is called puberty. Puberty tends to start around the age of 11 or 12, with girls starting puberty about one year earlier than boys on average. Puberty is broken up into “Tanner Stages” with the end result being a full-grown adult.

What most people see during puberty is a child becoming an adult before their very eyes. This means more lean muscle mass, an adult build, and a change in the weight distribution across the body. While these surface changes are important, it is also vital to discuss how these changes impact body composition.

In this article, we will share the ways that body composition changes during puberty and also discuss the impact that these changes can have on the long-term health of children as they grow towards adulthood.

What is Body Composition?

Body composition is the term used to describe the proportion of various substances that make up the body. Some of these substances include:

• Water

• Fat

• Protein

• Minerals

Sometimes, body composition is referred to simply as fat mass versus fat-free mass. Every aspect of body composition is important for a different reason; it is not just about gaining or losing weight. It is more about the type of weight that is lost and whether or not people are gaining lean muscle.

These changes are most evident as a child goes through puberty. As a child develops into an adult, there are numerous changes that impact body composition. All of these can have long-term effects on their adult health.

The Overall Effects of Puberty on Body Composition

As children go through puberty, there are significant effects on the adiposity, lean body mass, bone mineral content, and density. A research paper was published in the Journal of Current Opinions on Endocrinology, Diabetes, and Obesity, showing that there is a significant difference between boys and girls as they go through puberty. These differences arise because of differences in:

• Estrogens

• Androgens

• Growth Hormone

• IGF-1

• Genetic Factors

• Ethnicity

• Environmental Factors

The researchers reviewed numerous studies, reaching a number of overarching conclusions, including that:

• Males gain more fat-free mass, such as skeletal mass

• Females gain more fat mass

• Both males and females add bone mineral density at the highest rate during their pubertal years

• Males tend to assume a more android body shape

• Females bodies assume a more gynecoid shape

This information is important because it can impact adult body composition, which can impact a child’s pubertal timing, and depending on the circumstance can either increase or decrease their risk of developing diseases down the road.

One of the major implications of puberty and its changes in body composition is the impact that it has on your child’s long-term health. It is important for children to take care of their bodies during puberty because poor body composition even in their younger years can lead to diseases with deadly complications in the future.

The Impact of Body Composition on Disease Processes

The body composition changes that occur during puberty are markers of major metabolic changes. While these metabolic changes are important for proper growth and development, they also go a long way towards determining someone’s future health. Therefore, it is important to accurately measure body composition even in childhood years.

Recently, a research paper was published in the journal Hormone Research in Pediatrics. The researchers reviewed several body composition components and the tools that are available to measure them. Some of the important body composition components include:

• The percentage of body fat

• The percentage of lean body mass

• Total body fat

• Total Lean Body Mass

• Bone-mineral content

All of these are important because they play a role in someone’s overall health. According to the researchers, some of the tools available for measuring these components include:

• Anthropometry, or the basic tools used to measure someone’s height and weight

• Duel-Energy X-Ray Absorptiometry, or DEXA scans, which measure bone mineral density

• Bioelectrical Impedance Analysis, which uses electrical resistance to measure total body composition

Ultimately, these measurements are important because they can help someone determine their risk of developing a disease with dangerous complications down the road.

The researchers emphasize that the body composition risk factors that are most associated with diseases in adulthood stem primarily from body fat and bone mineral content.

In this paper, authors state that “adipose [fat] tissue is endocrinologically active.” This means that it plays a role in hormone regulation within the body. However, with too much body fat, this can cause hormone dysregulation and has influences on metabolic processes that can increase risk for diseases such as diabetes and cardiovascular disease.

These findings were supported by another research article showing the importance of body composition in the development of cardiovascular disease. The researchers examined those who had become and maintained an overweight status for their entire lifetime and compared them to those who were never overweight. Findings displayed that men and women with a higher lipid profile were more likely to be overweight or obese and were more likely to have higher blood pressures.

These findings support the conclusion that adipose tissue drives an increase in cardiovascular risk factors, leading to the development of atherosclerosis, heart disease, and possible blood clots.

The other body composition risk factor associated with disease later in life is bone mineral content, and the importance of it during the pubertal years can be seen in this article published in the Journal of Clinical Densitometry. In this article, the researchers monitored the bone mineral content and density of close to 100 males and 100 females for a period of 4 to 5 years. The researchers found that the highest rate of rise of bone mineral density was during the pubertal years.

The researchers go on to say that the peak bone mineral content was achieved shortly after puberty. This demonstrates the importance of making sure that children are taking care of their bones during puberty by developing skeletal muscle mass. This will reduce their chances of developing osteoporosis down the road.

Body Composition and its Impact on the Timing of Puberty

Body composition can even impact on when a child will start puberty, with research showing that a higher percentage of body fat leads to an earlier puberty start time.

In the study, the researchers collected data on more than 3,000 girls and boys. They measured adipose (fat) tissue using a variety of measurements, including skinfold thickness. The researchers tracked the children as they went through puberty, noting the age at which they reached various stages.

The researchers found that children who had higher levels of adipose tissue reached the various Tanner stages earlier than their peers. But why does this matter for children?

This matters because fat tissue is endocrinologically active, meaning that it is involved in hormone regulation. Adipose tissue produces pubertal hormones, triggering an earlier onset of puberty. Unfortunately, this also means that this can lead to health complications such as a shorter adult height and increased cardiovascular disease risk.

Changes in height due to early puberty can be seen through this study published in the journal of Hormone Research in Pediatrics. In the study, the researchers tracked about 100 girls as they progressed through puberty, with half of them having an accelerated pubertal course due to central precocious puberty (a condition that causes early sexual development). The researchers had a defined target height for the girls that was generated from the heights of their parents.

Those who had an accelerated pubertal course had a final adult height that was significantly shorter than their target height. Those who progressed through puberty at an average rate tended to reach a final height that was very close to their target height. The results show that children who progress through puberty earlier will achieve a shorter overall adult height due to earlier growth plate closure.

Lastly, another study found that girls who progress through puberty earlier (defined as early menarche) are at risk of developing diseases such as:

• Cardiovascular disease

• Hypertension

• Type 2 Diabetes

Clearly, it is important for children to take care of their body as they go through puberty. It can have a profound impact on their overall health as an adult. Remember, children have to live with their bodies for the rest of their lives, so taking care of their bodies earlier will help set them up for a  healthier future.

Creating Healthy Habits Early On

It is evidently seen now the importance of body composition in children. It can have an impact on the timing of their pubertal development, their overall adult health, and their risk of developing diseases down the road.

There are inevitable changes that will happen in your child as a result of puberty. The goal is not for them to become a bodybuilder so that they don’t develop health risks. The goal is to maintain a healthy body even as their metabolism changes into adulthood.

So the next time you’re out with your family, take a walk at night instead of staying home to watch TV. Choose to snack on fresh vegetables and fruit so that you role-model what healthy dietary choices look like. Encouraging young ones to create healthy habits early on such as maintaining a healthy diet and exercising regularly can help set them up for success.

Sleep deprivation is a serious problem in this country, impacting people of all ages. With the advent of cell phones and laptop computers, children are glued to screens almost at all times. This merging of the school and home environment makes it hard for children to stick to a regular bedtime routine. Some kids may even find it hard to fall asleep once they are actually in bed with the blue light that screens put off keeping them awake.

With children taking home large amounts of homework, being kept up by their phones, and having an unprecedented number of extracurricular activities, many children are not getting the proper amount of sleep. When children do not get the right amount of sleep, this can have a negative impact on their growth, development, and overall health.

Recently, the American Academy of Pediatrics released an updated statement discussing the proper amounts of sleep for children by age. Their guidelines indicate that:

• Babies under 1 year of age should sleep between 12 and 16 hours per day, including naps

• Infants between 1 and 2 years of age should sleep between 11 and 14 hours per day, including naps

• Toddlers between the ages of 3 and 5 years need to sleep between 10 and 13 hours per day, including naps

• Children between the ages of 6 and 12 years should sleep at least 9 hours per night

• Teenagers need to be getting at least 8 hours of sleep

Even though parents have decent control of when their children go to sleep, their alarms are frequently determined by their school’s starting time. This, plus all of the many distractions in the world today, can lead to children failing to get the recommended amount of sleep. This can cause problems in their school performance but also their physical health.

What is Body Composition?

Body composition is a description of how the different substances in the body are divided. A few examples of the different components that come together to make a human body include:

• Water

• Protein

• Minerals

• Fat

While some people think of fat as a “negative,” all of these components play an important role in someone’s overall health. Therefore, instead of focusing on pounds gained or lost, focus should be shifted to where change is occurring in terms of body composition, specifically muscle gain or fat loss.

While most people assume that their body composition will only change based on their diet and exercise habits, sleep is a key contributor to maintaining a healthy body composition. The body’s metabolic processes do not stop just because someone is asleep. Therefore, it is important for people of all ages to understand the impact of sleep.

Sleep and Growth Hormone: Important in Children

Growth, in all ages, is primarily controlled by growth hormone. This hormone is regulated by the relationship between the hypothalamus and the pituitary gland, in which sleep plays an important role.

A review article that was published in Comprehensive Physiology showed that:

• Growth hormone levels peak during the onset of deep sleep

• Multiple smaller peaks were observed during other stages of sleep

• Those who have a delay in the onset of deep sleep have delayed peaks in their growth hormone levels

It has long been known that growth hormone levels peak during sleep. For children to grow, they need to have proper levels of growth hormone. This means that children need to have the proper amounts of sleep.

Even in preschool-aged children, sleep is vital for proper body composition. A research study that was published in Obesity measured the body composition of preschool-aged children at the onset of the study and at follow-up one year later. The researchers found that increased levels of sleep resulted in less overall fat mass and therefore a reduced percentage of body fat.

Even though some people associate sleep with laziness and increased adiposity, sleep in children is necessary for a healthy body composition. Children need to make sure that they are getting the proper amounts of sleep to allow their bodies to grow.

Sleep and Muscle Strength in Children

Sleep also plays an important role in muscle building in children. Even though children will build muscle as they run and play, most overlook the importance that sleep plays on muscle hypertrophy and strength.

A study published in the Journal of Sleep Research performed a cross-sectional study examining the sleep habits of close to 1,000 adolescents through a questionnaire. The researchers found that sleep was inversely related to markers of obesity, such as waist circumference, and positively related to skeletal muscle mass in boys.

Interestingly, the adolescents that had the most sleep were affected similarly to those with the least sleep. Both groups showed that waist circumference significantly increased, indicating that both too little and too much sleep can negatively impact body composition.

These results were echoed by another study that was published investigating the sleep habits of college students. While some university students view pulling the “all-nighter” as a rite of passage, researchers found that it can impact their muscle strength significantly.

This study looked at over 10,000 university students and found that males with a short sleep duration (defined as under 6 hours), when compared to those who had a good night’s sleep (more than 7 hours), had reduced muscle strength.

There are lots of reasons why this decrease in muscular strength occurs. For one, as people sleep, protein synthesis increases, allowing people to rebuild the muscle that is broken down over the course of the day. Therefore, it is vital for everyone to get enough sleep to help rebuild their muscle fibers.

Sleep Plays a Direct Role in Obesity

There are more children in the United States who are overweight or obese than ever before. This excess fat tissue leads to the development of numerous health problems including high blood pressure and diabetes. While proper diet and exercise are critical for maintaining a healthy body composition, sleep plays a vital role in the management of obesity as well.

The importance of sleep begins even in the toddler years, based on a study that was published in BMC Public Health. The researchers combined data from close to 70 research articles, totaling close to 150,000 people from almost two dozen different countries. The researchers assessed the sleep of children via parental report or measured the sleep habits directly.

The researchers found that shorter sleep duration led to higher rates of body adiposity in addition to impaired growth, increased screen time, and poor emotional regulation. This means that children who sleep more, even during the toddler years, are more likely to have a favorable body composition, marked by a lower body fat percentage.

These results were backed up by a similar study carried out on children between the ages of 7 and 9, which was published in the American Journal of Human Biology. The researchers performed a cross-sectional study on more than 4,500 children. The height, weight, and skin folds of the children were measured and sleep data were collected via a parent survey. The researchers found that:

• Children who slept fewer than 9 hours per night was more than three times as likely to be overweight or obese when compared to children who slept greater than 9 hours per night

• Children who slept more than 11 hours had a body fat percentage of 20.9 when compared to children who slept less than 9 hours, who had a body fat percentage of 23.4 (p < 0.001)

Even though parents might associate more sleep with more sedentary activity, sleep is actually important for children to maintain a healthy body composition. The body needs time to rest and recharge as it gets ready for the next day. Furthermore, the body needs sleep to carry out the growth and development that is critically important to young children.

So, what do all of these studies mean? An article published in Obesity Reviews sought to tie a lot of these results together. The researchers indicated that regular lack of sleep can lead to:

• Higher levels of insulin resistance, leading to higher cortisol levels, that may eventually lead to the development of diabetes

• Higher blood pressures and salt retention, linked to cardiac problems

• The development of diabetes can increase appetite and alter metabolism, leading to changes in body composition and the development of obesity

All of this demonstrates that proper amounts of sleep are vital in the treatment of obesity and excess adiposity. Therefore, any obesity treatment plan should address sleep as a cornerstone to the intervention.

Proper Amounts of Sleep are Crucial to Overall Health

It can be hard for children to get the proper amount of sleep at night. Because of how connected children are today, it is difficult for kids to separate the school environment from home. This leads to challenges in establishing a consistent bedtime routine.

For children, it is vital to make sure that they get to bed at night. Sleep plays a critical role in school performance, social development, growth, and overall health. Even though homework and sports can make it hard for children to get to bed on time, it is important for parents to work hard to keep the bedtime consistent. This means avoiding electronics and exercise prior to bed and staying away from caffeinated drinks such as soda, to keep the body in a regular rhythm. Teaching good sleep habits early can help children to develop properly and maintain health (and a good body composition) into adulthood.

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David Randolph graduated from medical school at the University of North Carolina in Chapel Hill. He is currently completing his Residency in Pediatrics at the University of South Carolina.