5 common Causes of excess Weight gain in teens

✔ Research-backed

Teenagers acquire weight gradually as they mature. Although a healthful increase in weight is necessary, excess weight gain in teens and the accumulation of additional calories might be concerning. The most prevalent causes of significant weight gain in teenagers are a poor diet and a sedentary lifestyleiA pattern of living characterized by sitting, lying down often, with little or no physical activity , including lack of physical activity. However, hormonal changes during adolescence and an underlying medical condition in a few cases can also induce a sudden increase in weight in teenagers. While teenagers need to keep excessive weight gain in control, they should not deprive themselves of the regular weight increase that is necessary for their healthy development. Dive into this post as we discuss the appropriate weight gain for teens, some common reasons for excessive weight gain or adolescent obesity, and what can be done to maintain a healthy weight in teens.

In This Article

What Should Be the Ideal Weight of Teens? 

Use BMI calculator to determine teenager's weight

Image: Shutterstock

To determine the ideal weight of the teen, you need to consider several factors besides their age.

  • The US Center for Disease Control and Prevention (CDC) and the American Academy of Pediatrics recommend the use of a BMI calculator to determine if a teen has normal weight, overweight, or obese (1).
  • The BMI calculator considers the height and age of the teenager in determining their weight threshold.
  • Body Mass Index for teens is interpreted differently, which is why you should refer to a BMI chart, such as the one developed by the CDC, standardized for children.
  • The CDC says, “Because there are changes in weight and height with age, as well as their relation to body fatness, BMI levels among children and teens need to be expressed relative to other children of the same sex and age (2).” Therefore, the weight of a teen is evaluated in comparison to other teens and is assigned as a percentile.
  • The minimum is the 5th percentile, and the highest is the 95th percentile. When the teen’s BMI is equal to or greater than the 95th percentile, they are considered obese since it means the teen’s weight is greater than 95% of teens.

protip_icon Experts say
The US CDC recommends checking a teen’s BMI at least once a year. However, it is often checked by a healthcare provider (17).

Ultimately, the teen’s BMI score on the percentile chart will determine whether they are of a healthy weight or fall within the bracket of overweight teenagers.

BMI Percentile Table and Weight Status 

Percentile RangeWeight Status
Less than the 5th percentileUnderweight
5th percentile to less than the 85th percentileNormal or healthy weight
85th to less than the 95th percentileOverweight
Equal to or greater than the 95th percentileObese

Source: US Centers for Disease Control and Prevention 

BMI Calculation and CDC Charts 

You can calculate the BMI of the teen using the following formula:

  • Weight (kg)/ (Height in meters x Height in meters)
  • (Weight (lb) x 703)/ (Height in inches x Height in inches)

Round off the number to one decimal place. For example, 22.554 becomes 22.5.

You can calculate the BMI of your child and plot it on the chart right at home:

CDC BMI Chart For Boys

CDC BMI Chart For Girls

protip_icon Point to consider
Not all children and teens with the same BMI are obese or overweight. This may vary depending on the age. For instance, a 12-year-old and a 16-year-old with the same BMI can fall into different categories on the percentile chart (17).

What Causes Excess Weight Gain In Teens?

Here are a few reasons that contribute to excess weight gain in teenagers (3).

1. Eating unhealthy food

Eating unhealthy food causes excess weight gain in teens

Image: S: iStock

  • Unhealthy snacking between meals can accumulate excess calories that cause weight gain. This is particularly common when teens feel “bored” and go every now and then to the kitchen or the refrigerator looking for food that makes them feel better.
  • Teens are likely to gain weight if they eat high-calorie, low-nutrient fast food even if they have a nutritious diet at home.
  • Access to junk food combined with the freedom that their pocket money gives them can also result in building unhealthy eating habits. Regular binge eating of fast foods and processed foods can lead to weight gain.

2. Insufficient physical activity 

  • Teenagers need to get adequate exercise to stay in good health. When a teen lacks physical activity, then they invariably gain weight. According to the CDC Youth Risk Behavior Survey (YRBS), there was a decline in physical activity and an increase in sedentary behavior among US teenagers between 2011 and 2019. Additionally, in 2019, only 23.2% of teenagers engaged in 60 minutes of physical activity per week, while 46.1% indulged in playing video or computer games for three or more hours daily.
  • Children who do not eat junk food may also be at risk of putting on over weight if they do not exercise at all.
  • Teenagers burn fewer calories when at rest, according to a study (4). The study noticed that 15-year-olds burn 400 to 500 fewer calories per day when at rest, compared to what they did at the age of ten years.

3. Puberty

Hormonal changes during puberty causes excess weight gain in teens

Image: Shutterstock

  • Puberty alone may not cause significant or unhealthy weight gain. However, the growth spurt tends to cause increased hunger, which may accelerate weight gain in teens who eat in excess and do not get enough physical activity.
  • Children in their early teens (13 to 14-year-olds) are likely to gain weight naturally as a result of hormonal changes during puberty. Weight gain may be more prominent among girls (5).
  • The child may gain about 6.5 pounds (3 kilograms) in a year after puberty (6).

4. Psychological reasons 

  • The changes in the body make adolescents highly self-conscious and sensitive to their figure. They may unnecessarily compare themselves to their peers and be under pressure of having the “ideal body” (7). The dissatisfaction of not having the perfect body may lead to mental health disorders like depression, which in turn could lead to unhealthy eating habits, eating disorders, and thus weight gain (8).
  • Several teens have a flawed opinion that they are fat even when they are not, which could lead to body image issues. In the long run, this could lead to reinforcement of the belief. Some experts state that a teenager’s constant belief that they are fat can lead them to gain excess weight (9).
  • Stress and emotional eating are also linked to weight gain. Research suggests that stress and depression can lead to higher consumption of sugary and fat-rich foods (10). Food is quite likely to work as a coping mechanism to alleviate the feelings of depression and chronic stress.

Kritika Khurana, a student, shares her story of how stress-induced eating habits caused her to gain weight. She says, “I started gaining weight during my board (exams), and I was so sad with my weight that I stopped going out with family and friends because I never felt good in my skin. As unhappy as I have been with my weight, I ate more just to change my mood and feel better, and as a result, I gained more weight.

“There was a time when I suffered from depression, too. And then my mom came to my rescue. She forced me to go and join a diet clinic. As I started going to the clinic, I started seeing the changes, and my lifestyle changed because I no longer wanted to go back to the same old fat girl I used to be (i).”

5. Health reasons

  • Hypothyroidism is a condition where the thyroid gland becomes underactive and produces lesser thyroid hormone, one of the symptoms is an increase in weight (11). The teenager is also likely to feel tired and fatigued most of the time. This is most common in girls, particularly if some other woman in the family has thyroid disease.
Hypothyroidism causes excess weight gain in teens

Image: S: iStock

  • Cushing’s syndrome is a rare medical condition that causes the body to produce an excess of cortisol, which is the stress hormone produced by the adrenal glands (a gland that lies over each kidney). One of the significant symptoms of the condition is weight gain. Accumulation of fat around the base of the neck is another symptom. Children with Cushing’s syndrome tend to become obese and also grow slowly (12).
  • Certain medicines can also lead to excess weight gain due to the compounds in them. Sometimes, medications can cause complications that in turn, lead to weight gain. An example is glucocorticoids, which is a type of steroid hormone commonly used in the treatment of immune system disorders like asthmaiA long-term respiratory condition wherein the airways of the lungs become swollen and narrow, resulting in breathing problems and lupusiA chronic autoimmune condition causing inflammation and damage to various body parts . Long-term use of glucocorticoid can cause Cushing’s syndrome, which in turn leads to weight gain.

protip_icon Quick fact
Inadequate sleep and emotional issues can contribute to obesity in teenagers (18).

Excessive weight gain can be controlled through changes in lifestyle and diet. But if that doesn’t help, you may have to consult a medical professional.

Whatever the underlying causes, obesity has become more common as children reach adolescence. As shown in the graph below, collected from the National Health and Nutrition Examination Survey of 2017-2018 in the US population, it has been observed that among children ages 2-5 years, more than 1 in 8 (13.4%) have obesity, which increases to more than 1 in 5 (20.3%) in children 6-11 years and more than 1 in 5 (21.2%) among teenagers.

Prevalence of obesity in US children and adolescents aged 2 to 19 years

Source: Overweight & Obesity Statistics; National Health and Nutrition Examination Survey (NHANES)

When To Be Concerned About Weight Gain? 

Consult a doctor about your teen’s weight gain if:

  • The child has extreme weight gain beyond 16 years of age and even towards the end of the teen years (2) (4).
  • You sense the teen is gaining weight due to binge eating, which itself may have been caused by constant peer pressure, body image issues, or some other matter that is stressing them out.
  • The weight gain seems to have begun after the kid was prescribed medicine. In such a case, talk to the doctor about it.
  • The body develops abnormally high deposits of fat around the neck, face, and the abdomen. The skin on the abdomen has reddish-pink stretch marks (these are the symptoms of Cushing’s syndrome).
Abnormally high deposits of fat in teens could be concerning

Image: Shutterstock

  • The child also appears tired, dull and complains of muscle aches.

Complications Of Obesity In Teens

Unhealthy weight gain in teens can lead to several complications, affecting their quality of life. Some of the physical complications include (13):

  • Diabetes
  • Changes in hormone levels
  • Sleep issues
  • Pain in joints
  • Breathing problems
  • Increased risk of cardiovascular diseases
  • Increased blood pressure

Apart from the above-listed physical complications, teens with obesity can also face emotional problems including low self-esteem, anxiety, and depression.

Frequently Asked Questions

1. What is considered a healthy weight gain in teens?

A weight gain of one to two pounds per week is healthy for teenagers. However, all teens may not follow the same pattern. If the overall weight gain in a month is in the right direction, according to your doctor, there is no need to worry (14).

2. Can a skinny teenager gain weight?

Yes, a skinny teenager can gain weight; however, gaining weight should not be their motive unless suggested by a doctor. At times, in an effort to put on extra weight, teenagers tend to accumulate unnecessary fat in their bodies, which may have adverse health effects. Therefore, teenagers should focus on building a healthy and strong body rather than gaining weight (15).

3. How often should teenagers eat?

A teenager may eat three meals a day with healthy snacks in between. They should include plenty of fiber in their diet and decrease salt and sugar consumption (16).

Hormonal factors and an unhealthy lifestyle with poor diet and nutrition may contribute to excess weight gain in teens. In addition, consumption of unhealthy, fatty foods, junk foods, or excessive intake of calories followed by a sedentary lifestyle may contribute to weight gain. Even puberty and psychological issues are contributing factors. Seek the help of a medical professional for the proper diagnosis of a teenager’s weight gain, which may often be evident by their body mass index (BMI) value. The underlying contributing factors must be considered before forming any interventional strategies for weight management or diet plans for weight loss in teens.

Infographic: Possible Causes Of Abnormal Weight Gain In Teenagers

Teenage weight gain is a typical cause for concern, and various factors might play a role. Knowing the reason behind your teen’s excessive weight gain is crucial, in addition to encouraging them to eat wisely and exercise frequently. See the infographic below to learn about typical reasons for teens’ excessive weight gain.

causes of abnormal weight gain in teenagers (infographic)

Illustration: Momjunction Design Team

Key Pointers

  • A poor diet and a sedentary lifestyle are key factors behind excessive weight gain in teenagers. However, hormonal imbalances and underlying medical conditions could also be responsible.
  • The ideal weight of a teenager can be measured by using the BMI calculator which considers the child’s height and age to determine the weight.
  • Factors such as puberty, psychological reasons, health reasons, and certain medicines may contribute to a child gaining weight, apart from a poor diet and lack of physical activity.
  • Consult a doctor if your teen is gaining weight due to binge eating or if weight gain seems to have begun after a particular medication, or if their body develops abnormally high deposits of fat around the neck, face, and abdomen.
Excess Weight Gain In Teens_illustration

Image: Stable Diffusion/MomJunction Design Team

Personal Experience: Source


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.

1. Age-based Pediatric Growth Reference Charts; Baylor College of Medicine
2. About Child & Teen BMI; Centers for Diseases Control and Prevention
3. Weight Management and Adolescents; Children’s Hospital Philadelphia
4. Teenage weight gain down to dramatic drop in calories they burn; University of Exeter/Science Daily
5. Stages of puberty: what happens to boys and girls; NHS UK
6. Physical Changes During Puberty; American Academy of Pediatrics
7. Adolescent development; U.S. National Library of Medicine
8. Felton et al., The relation of weight change to depressive symptoms in adolescence; National Center for Biotechnology Information
9. Feeling overweight could make you fat; ScienceNorway.no
10. M Mooreville et al., Depressive Symptoms and Observed Eating in Youth; National Center for Biotechnology Information
11. Underactive thyroid (hypothyroidism); NHS UK
12. Cushing’s Syndrome U.S. Department of Health and Human Services Follow us: Twitter Facebook YouTube13. Obesity In Children And Teens; The American Academy of Child and Adolescent Psychiatry
14. Healthy Weight Gain for Teens: A Guide for Parents; Young Men’s Health15. Should I Gain Weight? Nemours Teens Health16. Healthy Eating During Adolescence; Johns Hopkins Medicine17. About Child & Teen BMI; US CDC18. Obesity In Teens; University Of Rochester Medical Center

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Dr. Miguel Ángel Guagnelli obtained an MD from Universidad Nacional Autónoma de México (UNAM) and specialized in Pediatrics at “La Raza” National Medical Center. He has a masters degree in Pediatric Endocrinology from Universitat Autònoma de Barcelona and a masters degree in Clinical Epidemiologý from UNAM.

Read full bio of Dr. Miguel Ángel Guagnelli Martínez