Many parents start to worry when they see their teen gaining weight. From rapid and unexpected weight gain to a slow and gradual filling out, there’s a lot going on during the teen years.

I’ve seen it over and over in my pediatric nutrition practice: teenage weight gain. Parents worry, but it’s not always something to be concerned about.

But, still, parents wonder if there’s something they should do about it.

If they should somehow intervene and stop it.

Many parents want to know how to handle teen weight gain without causing more problems, such as disordered eating or an eating disorder. 

Learn about teen weight gain and what you can do to help (without harming your relationship with your teen) in this article.

You’ll learn:

• What is considered normal weight in teens
• The common causes of too much weight gain
• Ways to help the teen who is putting on too much weight

Is Pre-Puberty Weight Gain Normal?

Yes, tween weight gain is a normal part of development.

It’s expected that all tweens will experience a weight increase, called preteen weight gain. When you look at the total amount of weight gained across the span of the teenage growth spurt, it is significant.

That awkward, pudgy appearance many tweenagers go through is a completely normal part of puberty.

Adolescent girls can gain fifteen pounds or so during puberty, while boys gain upwards of thirty pounds during this time.

[Read: When Do Girls Stop Growing?]

What Does the Average Teen Weigh?

The growth charts give you a sense of how your teenager is growing, and you can easily check it at your child’s next checkup.

Although these growth charts have a median, or “average” weight for each age, using this as a marker to check your child’s weight can be problematic.

Each child grows to his or her own potential. There really is no “average” teen weight or height. Teen growth is based on genetic predisposition and the environment within which they grow up.

The first way to assess whether weight is becoming problematic is to look at your child’s individual growth pattern over time. One point in time won’t give you the information you need to realistically assess what’s going on.

Over the years, is your teen growing along the same channel as usual?

If so, there’s nothing to worry about.

Or, is he jumping up on the charts into a higher percentile channel? Then there may be excess weight gain that could be worrisome. (Keep reading!)

What Causes Rapid Teen Weight Gain?

Rapid weight gain can be caused by several things: a disturbance in hormonal activity of the thyroid, for example, can lead to fast weight gain.

However, in many cases, rapid weight gain is a sign that extra calories, eating and activity is getting off track.

As a parent, there’s a fine line to walk when your teen, who is fairly independent with eating, starts to show signs of gaining too much weight.

Should you do something?

Or should you do nothing at all?

First, you need to understand what may be causing your teen to gain extra weight.

How Teens Grow and Gain Weight

According to Robert Malina, a researcher on childhood growth, adolescents gain weight and height in a predictable pattern. Height growth occurs first, followed by weight gain.

I like to call this pattern of growing “stretching out, then filling out.”

(This is different from childhood growth where pudginess often happens before increases in height.)

In teen girls, peak height growth occurs between ages 11-13 years. In boys, the peak height gain happens between 13 and 15 years, on average.

The weight gain from lean tissue (read: muscle and bone) during this time is about 15 pounds for girls and twice that for boys (~30#).

Girls gain about 15# of lean tissue (muscle and bone) during adolescence while boys gain about 30# during this period.

Additionally, girls gain more fat (~6#) on average than boys (~3#).

[Read: When Do Boys Stop Growing?]

Given these “norms,” and the typical signs of the growth spurt that go along with it, you can begin to see that an important physical transformation happens for teens.

A 15-30# weight gain in a couple of years can be shocking, especially if you’re used to looking at a lean child, but it is normal.

(Even if weight gain is beyond these “norms,” it can still be normal for your teenager, depending on the historical growth pattern. Remember: Take a look at the growth charts.)

What may not be normal is large meals and extra calories, both of which can cause unwanted and unhealthy weight gain.

Another contributor: Lack of regular exercise. When teens aren’t active, it can promote an imbalance of energy. Meaning, energy consumed is greater than energy burned.

Read: How to Be a Fit Kid

What’s Behind Accelerated Growth?

In 2012, 21% of teens aged 12-19 were classified as “obese,” a term that simply indicates that an individual is carrying too much body fat, according to the Centers for Disease Control (CDC).

Note, some teens are genetically predisposed to carry more body fat. That’s a topic for another article, however, if you want to learn more about this, listen to my podcast interview with Ted Kyle.

If your teen is gaining too much weight, here are some common reasons:

1. Independence

The increased independence associated with adolescence can lead to more eating. For example, a teenager with a new driver’s license may land in the drive thru lane.

He may gather with friends at the local coffee shop. Or grab lunch and dine out more often.

Translated: extra calories.

2. Reduced Physical Activity

Teens may not get daily activity if they don’t play a sport. School-based physical education has been declining for decades.

The opportunities for natural activity is reduced due to classroom schedules and lack of gym time.

This can slow metabolism and reduce daily energy expenditure (also known as daily calorie burn).

3. Food Choices

Food choices may not be rooted in wholesome, nutritious foods. Fast food, junk food, ultra-processed foods, candy, and other unhealthy choices may be the norm rather than the rarity.

All these foods can contribute to a high calorie diet.

4. Bad Eating Habits

Eating habits can also play a role. Late night snacking, skipping breakfast and social eating can disrupt appetite regulation and add extra calories to the overall diet.

All told, there are many reasons that teenagers may experience unwanted weight gain.

Unexplained Weight Gain in the Teenager

It can be hard to figure out why weight gain is happening. The first thing you want to do is assess whether your teen is going through her normal stage of growth and development.

If weight and height seem to be progressing along a normal path, then you’ve got nothing to worry about (and nothing to say).

If there is a clear bump up in your teen’s weight curve, indicating sudden or excess weight gain, I still believe you should say nothing about it to your teen.

Why?

Because calling out weight gain can be very disturbing and disruptive to her developing self-esteem and body satisfaction.

Body dissatisfaction has been highlighted as a risk factor for dieting and other dangerous, weight-reducing efforts.

It’s also may be a contributor to the development of an eating disorder.

Some teens will have a medical issue going on that causes unexplained weight gain, such as thyroid problems or hormonal imbalances. Certain medications can also contribute to weight gain.

If you suspect these, talk with your doctor.

What You Say Can Help or Harm

If you have concerns about your teen’s weight, tread lightly, particularly with what you say to him or her.

Starting on a tirade of what’s healthy to eat and what’s not, or extolling the virtues of exercise will likely be received as hurtful commentary.

Nagging your teen to exercise, or commenting on her appearance may do more harm than good. It is unlikely to motivate her to eat better or exercise more.

In fact, it can make eating worse and turn your teen off from exercising!

Many teens will be self-aware. They know their bodies are changing. They may be secretly unhappy or self-conscious about their weight or appearance.

You may hear questions like, “Do you think I’m fat?”

Don’t panic if this happens. Many teens are simply looking for your reassurance and acceptance.

Weight Loss in Teens: Should Teenagers Diet?

Weight loss diets aren’t a good idea. But it’s normal to wonder and think about this. We have a culture of dieting, and our teens are experiencing it, too.

The pursuit of weight loss with restrictive diets can lead to lifetime of yo-yo dieting, poor self-esteem, and a higher risk for mental health problems.

You can, however, help your teen move toward healthy eating patterns and lifestyle choices. And this is the safer path for teens.

When Your Teen Isn’t Concerned about Weight

Your teen may not be as concerned about her weight as you are. She may tune out your lectures about long-term health.

An appointment with a dietitian or other health care provider, if not inspired by your teen, may be unsuccessful. It could even be damaging.

Teen Gaining Weight: How to Help without Harming Them

Most parents can’t stand to watch their teen overeat, or sit around and be lazy. They want to do something about it!

This often turns into nagging, inspirational discussions, or offers of help.

These direct interventions often fall flat with teens.

The good news, though, is that there are plenty of things you can do to help your teen without harming her.

Here are four positive ways to encourage healthy eating and weight:

#1: Create a Healthy Food Environment

You are the nutritional gate keeper in your home. In other words, you allow food in. You choose it, purchase it, and stock it.

While you can’t do much about your teen’s eating patterns outside of your home, you can keep your homestead healthy.

Make sure you’ve got plenty of healthy snacks and nutritious items in your kitchen pantry and refrigerator. Place them front and center.

Because teens are growing rapidly, they have a voracious appetite and will often eat what’s available to them.

Stock up on healthy snacks such as yogurt, cut up fruit, vegetables, whole grain cereals and breads, nuts, seeds, popcorn and more.

Stick with regularly timed meals and snacks, so overeating due to hunger isn’t likely to happen.

#2: Be a Good Role Model

Show your teen what it means to eat healthy and exercise. Lead by example, not by talking about the virtues of being healthy.

Remember, actions speak louder than words. Be what you want your teen to be: a healthy eater, a regular exerciser and a good sleeper.

I know from my own experience as a mom of teens, what my teens see me doing day in and day out sets the bar for how they will conduct their daily lives.

#3: Keep the Lines of Communication Open

Be non-judgmental and open to discussing your teen’s body and weight concerns.

Your teen may tell you that he is frustrated with his lack of muscle, or the appearance of his belly, or that he is uncomfortable in his clothing.

That’s your lead in for a productive conversation. Your intention should be to help: “Is there something I can do to help with that?” is a good response to these concerns.

Just being available to listen without unsolicited suggestions can work wonders.

#4: Invite Your Teen to Join You

Often, teens are leading an independent life, hanging out with friends, studying on their own, and hardly around the house.

When you can, invite your teen to go for a walk, to a movie, to the grocery store, to a local event, or to the gym.

An invitation to your teen is a sign you’re still interested in spending time together, which can go a long way in keeping the relationship strong and opportunities for communication and your influence alive.

For anyone who experiences weight gain, the motivation to change eating habits or exercise comes from within – teens included.

In other words, if your teen wants to work on this, she will because she is motivated to do so.

Being told what to do, or what to eat may fall on deaf ears, or be met with resentment or resistance.

Be ‘chill’ with your teen on the topics of weight and exercise, but be ready and open to help when you’re called to do so.

Have you had an experience with this? How did you handle it?

What if Your Teen Has Sudden Weight Gain?

Usually, weight gain in teens is a gradual process, but sometimes, a teen may have what appears to be sudden weight gain. This may be due to lifestyle choices, but sometimes lifestyle is in a good place, but the weight keeps piling on.

You may need to further investigate medical causes of sudden weight gain, such as a hormonal imbalance, or a condition associated with imbalanced hormones, like polycystic ovary syndrome (PCOS).

Talk with your family doctor regarding additional testing to rule out or uncover a medical condition that may be responsible for your teens sudden weight gain.

Need More Help with Feeding Teens?

If you want the input of a pediatric nutrition professional’s expertise and guidance on the food, feeding and habits that lead to a healthy teen, check out our online class called The Nourished Child Blueprint. 

It will help you set up a healthy home food environment, use positive interactions around food, and help you understand optimal ways to promote your teen’s autonomy so he’s ready to leave the nest.

For other classes, workshops and guidebooks, visit The Nourished Child.

Is Your Teen RAPIDLY GAINING WEIGHT? (HOW to Set Your TEENAGER Up for HEALTHY EATING)

This post was updated on September 12, 2020.