America’s Teens Are Struggling in Body and Mind. Their Own Two Feet May Be Part of the Answer.

If you are raising a teenager right now, or you love one, you have probably sensed that something is off. Our young people are more anxious, more worn down, and more sedentary than any generation before them, and their bodies are developing problems I used to see only in middle-aged adults. After more than 40 years in medicine, I do not say that lightly. But I also want you to know the picture isn’t hopeless. A large new study published this month in JAMA Network Open adds to a growing body of evidence that one of the simplest things a teenager can do, putting one foot in front of the other more often, is tied to better mental health and even to measurable differences in the developing brain.

In this article, I’ll walk you through where our teens really stand, why they have stopped moving, what this new research found, and what you can do as a parent starting this week.

The Report Card No Parent Wants to See

Let me start with mental health. In the CDC’s newest Youth Risk Behavior Survey, which covers 2025 and was released last month, 33% of American high school students said they had felt persistently sad or hopeless during the past year. That is genuinely better than the 2021 peak of 42% and 40% in 2023, and I am grateful for that progress. Still, it is higher than the 30% reported in 2015, and the gap between girls and boys remains wide: 43% of girls reported persistent sadness, compared with 24% of boys. In 2025, 14% of high school students seriously considered suicide and 6% attempted it, both improved from 2023 but still far too high.

The federal National Survey on Drug Use and Health tells a similar story. In 2024, 15.4% of adolescents ages 12-17, roughly 3.8 million young people, had a major depressive episode in the past year, down from about 21% in 2021. Only about 6 in 10 of those teens received any mental health treatment at all. The same survey found that more than 4 in 10 adolescents reported symptoms of anxiety.

The longer view is sobering. According to the CDC’s National Center for Health Statistics, the suicide rate among Americans ages 10-24 rose 62% between 2007 and 2021, from 6.8 to 11.0 deaths per 100,000. Suicide remains one of the leading causes of death for young people in this country.

As a metabolic medicine physician, the physical numbers alarm me just as much. Federal measurements from the National Health and Nutrition Examination Survey (NHANES) taken between August 2021 and August 2023 show that about 1 in 5 American children and teens now have obesity. Among adolescents ages 12-19, the figure is 22.9%. A generation ago, in 1999-2000, obesity affected 13.9% of children and teens ages 2-19; it now affects 21.1%, and severe obesity has nearly doubled, from 3.6% to 7.0%.

Blood sugar is on a similar trajectory. Using NHANES data on about 6,600 young people, Liu and colleagues reported in JAMA Pediatrics that prediabetes among American youth ages 12-19 more than doubled, from 11.6% in 1999-2002 to 28.2% in 2015-2018. A 2026 analysis of the most recent NHANES data found that 30.8% of adolescents ages 10-19, nearly 1 in 3, now have either prediabetes or type 2 diabetes. Think about that for a moment. Nearly a third of our teenagers are already showing the early metabolic changes that, left unchecked, lead to type 2 diabetes, fatty liver disease, heart disease, and, as I discuss often on this blog, a more favorable environment for cancer later in life.

Fitness has slipped too. When the government last tested teen fitness on treadmills in 2012, only 42.2% of youth ages 12-15 had adequate cardiorespiratory fitness, down from 52.4% in 1999-2000. Not measuring it nationally for more than a decade is a problem in itself. And sleep, the foundation of both mood and metabolism, is in short supply: in 2025, only 24% of high school students got at least 8 hours of sleep on an average school night.

Why Our Kids Stopped Moving

The CDC’s 2025 survey found that only 25% of high school students were physically active for at least 60 minutes every day, and only 16% met the guidelines for both aerobic and muscle-strengthening activity. Girls are hit hardest. Only 18% of girls were active 60 minutes a day, compared with 32% of boys, and only 10% of girls met both guidelines. Just 20% of students attended physical education class every school day.

This is not only an American problem. A World Health Organization analysis published in The Lancet Child and Adolescent Health found that 81% of school-going adolescents worldwide did not get enough physical activity, with one of the widest gaps between boys and girls found right here in the United States.

Several forces are pulling in the same direction. The first is the screen. A 2023 Gallup survey found that American teens spend an average of 4.8 hours a day on social media, with girls at 5.3 hours, and the 2023 Surgeon General’s advisory warned that teens who spend more than 3 hours a day on social media face double the risk of symptoms of depression and anxiety. Every hour spent scrolling is also an hour not spent moving, sleeping, or being outdoors. The second is the steady disappearance of daily physical education and unstructured outdoor play, which have largely given way to scheduled, indoor, seated time. The third, which the authors of the new JAMA study name directly, is urbanization and digitalization. It is telling that rural students in the 2025 survey were more active than urban students.

A Challenge America Left Unfinished

None of this is entirely new. In December 1960, shortly after he was elected, John F. Kennedy wrote an article for Sports Illustrated called “The Soft American.” He was troubled by research showing that more than half of American children failed a basic test of muscular strength and flexibility, compared with fewer than 1 in 10 European children. Kennedy believed physical and mental vigor go hand in hand, and that a nation whose young people only watched from the stands while a few played on the field was risking its future. Once in office, he reorganized the President’s Council on Youth Fitness and made physical fitness a national priority.

One school became the model for that effort. At La Sierra High School in Carmichael, California, physical education teacher Stan LeProtti built a demanding program rooted in classical Greek ideals of movement mastery and body control, with progressive levels of achievement that students worked hard to earn. According to program alumni, students’ strength and physical habits changed dramatically within a few months, and the program spread to roughly 4,000 schools across the country. Former students describe more than physical results. Several have said the discipline taught them to push through physical and mental fatigue as adults, and that for students coming from troubled homes, the structure and encouragement gave them stability they did not have elsewhere.

The program faded by the 1970s, as parents lost interest in its rigor, budgets tightened, and the culture shifted. Today, La Sierra alumni and filmmakers behind the documentary project The Motivation Factor are calling on a new generation to finish what Kennedy started. Looking at the numbers I just shared, I think they are right. We once knew how to build strong, resilient young people. We simply stopped doing it.

The New Study: Every Step Counts

The research I most want parents to know about was published on October 1, 2026, by Qingyang Li, Amanda Paluch, and Divyangana Rakesh of King’s College London and the University of Massachusetts Amherst. They used data from the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term study of brain development in the United States, conducted across 21 sites. The researchers followed 5,515 young adolescents, about 12 years old on average and nearly half of them girls, who wore a Fitbit on their wrists for three weeks. This matters because a device measured their steps rather than a questionnaire estimating them. On average, these young people took about 9,600 steps a day.

The main finding was clear. Teens who took more steps had fewer mental health problems one year later, including fewer symptoms of anxiety, depression, attention problems, and acting out. That link held up after the researchers accounted for each child’s earlier mental health, family income, parental education, neighborhood disadvantage, access to green space, and body weight.

What struck me most was that the benefit did not level off. Compared with teens taking fewer than 5,000 steps a day, mental health scores improved progressively at 5,000-7,499 steps, 7,500-9,999 steps, 10,000-11,999 steps, and, best of all, 12,000 steps or more. Studies of physical health in adults often show benefits flattening out somewhere around 8,000 steps, but in these young people there was no ceiling. The authors summed it up simply: every step counts.

The researchers also looked inside the brain using MRI. More active teens had a slightly thicker cortex, the brain’s outer layer, in two areas. One is the paracentral lobule, which helps control leg movement and processes sensation. The other is the rostral anterior cingulate, which helps manage conflict and regulate emotion. Because the cortex naturally thins during the teen years, a thicker cortex in active kids may reflect a slower, healthier pace of change, though the authors note that only longer follow-up can confirm this. Remarkably, the greater thickness in the paracentral region statistically explained a small part of the link between more steps and better mental health a year later.

School grades were a different story. Overall, step counts were not linked to academic performance, and only the group taking 10,000-11,999 steps showed modestly better grades. The authors suggest that exercise’s learning benefits may depend on more vigorous activity than walking alone.

I want to be honest about what this study cannot tell us. It is an observational study, so it shows that active teens tend to have better mental health, not that the steps caused the improvement. Teens who feel better may simply move more, and other unmeasured factors may play a role. Step counters also miss activities like swimming and cycling; teens self-reported their mental health; the brain differences were small; and, ultimately, the families were somewhat more advantaged and healthier than those left out. I take these limitations seriously, and you should, too.

Why I Believe the Signal Is Real

What gives me confidence is that this study does not stand alone. It fits well with randomized controlled trials, the kind of research that can show cause and effect.

The most comprehensive summary to date, a 2026 umbrella review by Singh and colleagues in the Journal of the American Academy of Child and Adolescent Psychiatry, brought together 21 systematic reviews covering 375 randomized trials and more than 38,000 children and teens. Across 180 trials involving 34,490 young people, physical activity produced a meaningful reduction in symptoms of depression, and the authors rated the certainty of that evidence as moderate. A separate 2025 analysis of 18 randomized trials by Wang and colleagues found that aerobic exercise reduced depressive symptoms, with larger benefits in adolescents than in younger children and in young people with clinically diagnosed depression. The benefit peaked at about 590 MET-minutes per week, roughly two and a half hours of brisk walking or similar activity.

Movement may also help in the classroom. A 2025 analysis of 17 studies of school-based physical activity programs by He and colleagues found a small but real improvement in overall academic achievement, with math showing the most consistent gain. That aligns with the JAMA authors’ suggestion that more vigorous activity, rather than walking alone, may sharpen learning.

I also want to be careful here. Exercise appears to ease anxiety too, but the certainty of that evidence is lower than it is for depression. And while researchers have proposed several ways movement may help the brain, including raising levels of brain-derived neurotrophic factor (a protein that supports the growth and adaptability of brain cells), calming the body’s stress hormone system, lowering inflammation, deepening sleep, and strengthening self-control and self-esteem, the studies of these mechanisms in teenagers specifically have produced mixed results. They are reasonable explanations, not settled facts.

The Metabolic Payoff

This is where my own specialty comes in. Muscle is the body’s largest consumer of blood sugar, and when teenagers use their muscles, their metabolism responds quickly. In a randomized trial led by SoJung Lee and Silva Arslanian at the University of Pittsburgh, adolescent girls with obesity who did aerobic exercise for an hour, three times a week, for three months improved their insulin sensitivity and reduced fat in the liver and around the abdominal organs, without dieting and independent of weight loss. A companion trial in adolescent boys by the same group found that resistance training improved insulin sensitivity by about 27%. In other words, a teenager’s body begins handling sugar better within weeks of regular movement, long before the bathroom scale shows much change. We were designed to move, and our metabolism works best when we do.

What Parents Can Do Starting This Week

Exercise is not a cure-all, and it is never a substitute for therapy or medication when a teen needs them. But it is safe, inexpensive, and available to nearly every family. Here is how I would approach it.

Start by knowing the target. The Physical Activity Guidelines for Americans recommend that young people ages 6-17 get at least 60 minutes of moderate-to-vigorous activity every day, including vigorous activity, muscle-strengthening activity, and bone-strengthening activity (such as running and jumping) at least 3 days a week.

Then use steps as a simple scoreboard. An analysis of national activity-monitor data by Adams, Johnson, and Tudor-Locke found that about 11,500-14,000 steps a day, as counted by a sensitive research-grade activity monitor, best matched 60 minutes of moderate to vigorous activity in adolescents ages 12-17. On a simpler pedometer, which counts fewer steps, the authors suggest that works out to roughly 9,000 steps a day. Don’t let that number discourage you. Find out where your teen is starting and add 1,000-2,000 steps a day. Then add more. The new JAMA study suggests that every increase is worthwhile.

Build walking into ordinary life. Walking or biking to school when it is safe, walking the dog, taking the stairs, parking farther from the store, and making an evening family walk a habit all add up. I have found that a walk is also one of the best times to talk with a teenager, who will often open up side by side in a way they never will face to face.

Add some intensity and strength. Team sports, dance, martial arts, swimming, hiking, and simple bodyweight exercises such as push-ups, squats, and lunges cover the vigorous and strengthening work that steps alone miss. This is exactly what programs like La Sierra once provided.

Get outside whenever you can. In a study of more than 900,000 people in Denmark, Engemann and colleagues found that children who grew up with the least green space around their homes had up to a 55% higher risk of developing a psychiatric disorder later in life. Parks, trails, and backyards all count.

Make it social and let your teen choose. Group and team activities appear especially helpful for mood, and enjoyment is what makes any habit stick. Pay special attention to daughters, who are less active and report more sadness than boys; finding an activity and a group of friends that makes movement feel welcoming can make a real difference.

Trade screen time for move time. Set phone-free times and places, such as meals and bedrooms at night, and model the habit yourself. Children notice what we do far more than what we say.

Protect sleep. Teenagers need 8-10 hours a night, and regular daytime activity helps them fall asleep faster and sleep more deeply.

Finally, know when to get help. Persistent sadness, withdrawal from friends and activities, changes in eating or sleep, or any talk of self-harm call for a prompt visit with your pediatrician or a mental health professional. Exercise works best alongside professional care, not in place of it. Remember, you can call or text 988 at any hour.

The Bottom Line

Our teenagers are carrying a heavy load: too much sadness, too much time on screens, too little sleep, and bodies that are developing the metabolic diseases of middle age. Recent improvements in mental health surveys show these trends can be reversed. Physical activity will not solve everything, but evidence from a new study of more than 5,000 young brains and hundreds of randomized trials says it belongs at the center of the solution. It costs almost nothing, it can start today, and every single step counts.

Our children’s bodies are a gift entrusted to our care for a season. Helping them move, play, and grow strong is one of the most practical ways we can steward that gift well, and one of the most loving things we can do for them.

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