Phone Owners at 12 Were Twice as Likely to Tie Self-Worth to Weight

For many families, the first smartphone arrives around 12. It feels like a rite of passage.

A new study asks what else might arrive with it.

US researchers followed nearly 9,000 children. Those who owned a smartphone at 12 were more likely to report eating-disorder symptoms two years later.

It’s a link, not proof. But it’s a strong, careful link, and it adds to a growing pile.

What age should a child get a phone?

There’s no single right age. Major health bodies don’t set one.

The American Academy of Pediatrics encourages families to delay a first smartphone and decide child by child. It suggests a written family media plan, agreed together.

Some countries have gone further on social media. Australia set a minimum age of 16 for social media accounts, from December 2025.

The new research doesn’t give a magic number either. What it adds is one more reason to think hard about 12, and about what comes with the phone.

What the research shows

The study used data from the Adolescent Brain Cognitive Development (ABCD) Study. It’s a long-running US study that follows thousands of children’s brain development and health.

Children were recruited through schools at 21 sites across the country. The researchers looked at data collected between 2018 and 2024.

Who was in the study

The analysis included 8,957 children. Of those, 6,225 (69.5%) owned a smartphone at 12.

Parents reported whether their child had their own phone. The children themselves reported eating-disorder symptoms in a standard clinical interview, at 12 and again at 14.

The researchers asked about four symptoms:

These are symptoms, not diagnoses. Many children with one symptom never develop a full eating disorder.

The raw numbers

At 14, children who’d had a phone at 12 reported more of every symptom except worry about weight gain, which was rare in both groups.

Nearly 1 in 4 phone owners reported at least one symptom by 14. The authors call that burden a reason for urgency.

After adjusting for other factors

Phone owners differed from non-owners in many ways. They were more likely to be girls, further into puberty and from lower-income homes.

They also owned more laptops and smartwatches.

So the team adjusted for a long list of factors. These included sex, race, ethnicity, household income, parents’ education, puberty, body weight, parental monitoring, attention and depressive symptoms, and other devices.

The age-14 analysis also adjusted for symptoms the child already had at 12. That matters.

It means the link isn’t just children who already had symptoms getting phones.

After all that, owning a phone at 12 was still linked to higher risk at 14:

A risk of 1.49 times means roughly 49% higher, relative to similar children without a phone.

Girls and weight worries

At 12, girls with phones reported more worry about weight gain than boys with phones. The authors suggest early-adolescent girls may be especially sensitive to weight-related pressure.

Why would a phone matter?

The study didn’t test the reasons. But the authors lay out several plausible pathways.

• Comparison. Phones give private, constant access to idealised bodies on social media. Comparing yourself to them is a known risk factor for body dissatisfaction.
• Harmful communities. Pro-eating-disorder content and extreme “fitspiration” circulate easily. A personal phone makes it harder for parents to notice.
• Lost sleep. Night-time phone use can cut sleep. Poor sleep is linked to changes in appetite signals and emotional control.
• Coping. Stressful online content may push some children toward eating as a way to manage feelings.

There’s also timing. Early adolescence brings puberty, a stronger need for peer approval and still-developing self-control.

That’s a sensitive mix.

What earlier research found

Phones at 12 and broader health

A 2026 study in Pediatrics used the same ABCD cohort, with 10,588 children. Owning a smartphone at 12 was linked to higher odds of depression (1.31 times), obesity (1.40 times) and insufficient sleep (1.62 times).

Children who got a phone between 12 and 13 had more clinical-level mental health symptoms a year later.

Screen time and eating symptoms

A 2024 ABCD analysis of 10,246 children looked at hours, not ownership. Each extra hour of total screen time or social media was linked to higher odds of eating-disorder symptoms two years later.

Problematic social media and phone use were linked to all the symptoms studied.

How common disordered eating is

A 2023 meta-analysis in JAMA Pediatrics pooled 32 studies of 63,181 children and teens in 16 countries. About 22% showed disordered eating on a standard screening tool.

Rates were higher in girls, older teens and those with higher body weight.

How it fits together

The new study adds a missing piece.

Earlier work tied screen hours to eating symptoms. This one ties the timing of a child’s own phone to them, over two years.

How much should you trust this?

Promising. It’s a large, careful study, but it can’t prove cause and effect.

What makes it convincing

• A big, diverse national sample, weighted to look like US children overall.
• Two time points, with symptoms at 12 taken into account.
• A long list of adjustments, including other devices and parental monitoring.
• A validated clinical interview for symptoms, not a quick quiz.

What makes me cautious

• Phones weren’t randomly assigned. Families who give phones early may differ in ways the study couldn’t measure.
• Symptoms were self-reported by the children.
• The study didn’t know what kids did on their phones or for how long.
• Bullying, neurodevelopmental conditions and other mental health problems weren’t accounted for.
• Some groups dropped out more often, which may limit how widely the results apply.

What this means for you

• Delay if you can. The AAP encourages families to delay and individualise a first smartphone.
• A phone isn’t all or nothing. A basic phone for calls and texts covers safety without the feeds.
• Make a plan together. Agree rules on apps, times and where phones sleep at night.
• Keep phones out of bedrooms at night. It protects sleep, one of the likely pathways.
• Talk about bodies and feeds. Ask what they see online and how it makes them feel.
• Know the warning signs. Skipped meals, secret eating, harsh talk about weight or intense exercise deserve a conversation and, if they persist, a doctor’s visit.

The AAP’s Family Media Plan helps families set screen rules together. For signs and treatment, see the US National Institute of Mental Health’s guide to eating disorders.

If you’re in crisis, please contact a person, not a chatbot.

In the US, call or text 988. In the UK and Ireland, you can call Samaritans on 116 123, any time.

Elsewhere, Find a Helpline lists free services. If someone is in immediate danger, call emergency services.

In this short news report, Denver7 covers the earlier study on smartphones at 12 and children’s health:

What we still don’t know

1. Does the phone cause it? Only a trial or a natural experiment could show that.
2. Is it the phone or the apps? The study didn’t track what children did on their phones.
3. Does getting a phone later help? The authors want to see what happens when children newly get one.
4. How severe are the symptoms? Symptoms were counted yes or no, not by severity.
5. What helps? No one has yet tested which rules or limits reduce the risk.

My take: it’s not just the age

What I like about this study is its restraint. The authors found a consistent link and refused to call it proof.

I’m less convinced by headlines that will say “phones cause eating disorders”. The data don’t show that.

But the pattern keeps repeating across studies: earlier phones, worse sleep, more depression, now more eating worries. At some point a careful parent doesn’t need proof to act.

If I were deciding, I’d treat 12 as early, not late. And whatever the age, I’d care more about feeds, bedtime and conversation than the date on the box.