Childhood Obesity Just Hit a Record 21%. New JAMA Data Shows Why Early Action Matters.

A doctor at UW Health sees about 12 new families a week. That’s the pace at the UW Health Kids Fitness Clinic on Science Drive. Dr. Aaron Carrel and his team treat roughly 600 new kids a year for weight and lifestyle issues. The clinic has a waitlist. Dr. Carrel has said publicly that finding enough staff to help everyone who needs them is a real problem.

That waitlist is there for a reason. In the past month, two big things have landed for parents of school-age kids. Most parents haven’t seen them tied together yet.

First, the CDC posted new numbers. U.S. childhood obesity, ages 2 to 19, just hit 21.1%. That’s the highest level on record. Up from 19.3% in 2017-2018. The data comes from the latest NHANES survey , the agency’s most careful health survey. One in five kids.

Second, a team in Sweden ran the numbers on what happens later. They published in JAMA Pediatrics . One of the largest studies of its kind. They followed 6,713 kids with obesity for years, into adulthood. The kids who got better in treatment had much better adult health. Lower diabetes risk. Lower blood pressure problems. And in the combined response groups, the risk of dying by age 30 dropped by 88% compared to peers who didn’t get better.

Those numbers need some honest unpacking, which we’ll do below. But the headline is real. Every parent of a school-age kid in Madison should know it before summer starts.

What the Swedish study actually found

The team pulled records from a Swedish registry that tracks every kid in the country who gets treated for obesity. They followed 6,713 kids. The median age at the start of treatment was 12. They tracked them up to ages 18 to 30. They counted who got sick and who died.

Three groups emerged. Kids who got a “good response” (a real drop in their body size score). Kids who hit “remission” (no longer measured as obese). And kids whose numbers barely moved.

The gaps in adult health were big:

• Kids with a good response were 58% less likely to get Type 2 diabetes as adults.
• Kids who reached remission were 84% less likely.
• Remission kids were 60% less likely to get high blood pressure.
• And the combined good-response and remission groups had 88% lower risk of death in young adulthood than the kids whose weight didn’t change.

Lead author Resthie Putri summed it up: a good response to treatment in childhood led to lasting health gains, and to much lower rates of disease and death in young adult years.

That’s a striking finding. But here’s the caveat. This was not a randomized trial. It was a tracking study. Kids who responded well may have had families with more time, more money, or more room to stick with care. Those factors on their own could improve adult health. The authors say so: response to treatment cannot be pinned on the patient and their family alone.

Also: 88% is a relative number. Death rates for people in their twenties are very low to start with. So the change in raw risk is much smaller than 88% sounds. Big patterns, not proof of cause.

But the direction is consistent. And the lesson is consistent. What happens in childhood doesn’t stay in childhood. It builds up.

The catch nobody talks about: summer

There’s one piece of the research that should change how Madison parents think about June, July, and August.

A 2014 review pooled data from studies that tracked kids’ weight across school years and summer breaks. The pattern was hard to miss. Overweight and heavy kids made fitness gains during the school year — and lost most of them every single summer .

Overweight kids dropped about 7.9 BMI ranks during the school year. Then they gained about 4.2 back over the summer. Same pattern for heavier kids: down during school, up during summer. Six of the seven studies in the review found that summer gains were faster and bigger in kids who were already heavier.

The reasons are not fully pinned down. Likely a mix of less daily movement, more screens, late bedtimes, and the loss of school meals. As we wrote about earlier this month , summer is rough on kids’ mental health for some of the same reasons.

The takeaway is simple. Summer is when the damage happens. Programs that start in May or June and run through August are the ones that buffer the slide. Not “we’ll do something in the fall.” Right now.

Why “just exercise” isn’t the whole answer (and why it’s still the foundation)

Be careful with anyone selling a single magic answer. The honest research is messier than that.

The most recent reviews find that food and movement together beat either one alone. A 2024 review also found that exercise alone does not change how much kids eat afterward . So the “tire them out so they eat less” idea doesn’t hold up. Exercise doesn’t make kids hungrier either, which is good news. But it’s not a calorie eraser.

What movement does do is well-known. It helps the body use sugar better, builds lean muscle, lowers blood pressure, eases stress and low mood in kids (which we covered here ). And here’s the part that gets missed: it gives kids a steady weekly rhythm that families can build other habits around.

The leading group of obesity doctors put it bluntly in their 2024 guidance. The best childhood programs need 26 or more hours of family-based care over 3 to 12 months. That kind of program barely exists at scale anywhere. The doctors call for delivery in community, medical, or church centers — not just hospitals. That’s how you reach families who can’t take half a day off work for a clinic visit.

In other words: a program that meets kids where they are, runs year-round, treats movement as a social thing, and brings families along — that’s what the research keeps asking for. And what most towns don’t have.

What we see at Journey

We are not a weight-loss clinic. We don’t weigh kids. We don’t talk to them about their weight. That’s a parent and pediatrician talk, and at Journey we are careful to keep it that way.

What we are is a kids Brazilian Jiu-Jitsu program in Madison where 4-to-14-year-olds train two to four times a week, year-round, in a class with a coach who knows their name.

Every class is about an hour of real movement. An 8-minute warmup with games. 20 to 30 minutes of drills. Then 10 to 15 minutes each of guided and live sparring.

Kids who train two classes a week move hard for about two hours they might not otherwise move at all. Kids who come three or four times a week move for several hours more.

It’s not the only thing they need. But it’s the kind of steady, social, year-round movement that the research on how much less kids move now keeps flagging as the missing piece.

And because BJJ runs through the summer — every week, June through August — it’s the kind of program that breaks the summer-slide pattern the research keeps surfacing.

To be honest: there is no large randomized trial on BJJ and childhood obesity. The 2020 review of martial arts and body size found good signals but called for more research. We’re not going to claim science we don’t have. What we can say is that BJJ checks the boxes the research points to. Community-based. Family-friendly. Year-round. Steady. Builds stamina, strength, and body control. Burns real calories — judo and BJJ studies put it around 500 to 1,000 per hour for active grappling, depending on how hard kids go.

That’s a real piece of the picture. Not the whole picture.

Three things Madison parents can do this week

Not a “call us” list. Stuff you can do whether you ever hear of Journey BJJ again.

1. Pick a movement schedule for June, July, and August and put it on the family calendar today. Not “we’ll figure it out.” Real days. Real times. Summer break for MMSD kicks off in mid-June. The research says the gap between school ending and a new routine is where the slide happens.

2. Talk to your doctor if your kid’s growth chart worries you. The UW Health Kids Fitness Clinic takes referrals from local pediatricians. They have a waitlist. The earlier the talk, the better.

3. Cut one screen hour and swap in a movement hour, every weekday in June. Not zero screens — that’s not real life. One hour. Swapped, not just cut. (Here’s why we keep coming back to this .)

That’s the homework. None of it asks you to do anything we sell.

If you want to talk to us

If you’ve been thinking about getting your child into a real movement program for a while — or if this post is the nudge — the lowest-stakes thing you can do is come meet a coach.

It’s free. It’s a talk, not a sales pitch. You’ll meet our kids’ coaches, tour the gym, and find out whether the program is a fit for your kid before you sign anything. If it’s not a fit, we’ll tell you. There are things that make a family a poor fit for what we do , and we’ll say so.

Book a free Meet The Coach consult →

The CDC numbers are the highest on record. The Swedish data says what happens in childhood builds up for decades. And summer is the window where it gets worse. None of that is reason to panic. It’s reason to pick one thing this week and start.