Getting a first smartphone has become something of a modern coming-of-age ritual. Suddenly, children can talk to friends without going through their parents, watch videos in their bedrooms, join group chats, follow influencers and scroll through a digital world designed to keep them engaged. But that newfound freedom may come at a cost.
A new study published in the medical journal JAMA Network Open has identified a concerning association: Children who owned smartphones at age 12 were more likely to report symptoms associated with eating disorders by age 14 than peers who did not own a smartphone at that age.
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More research evidence of the effects of smartphones in childhood. Illustration
(Photo: shutterstock)
The researchers analyzed data from the Adolescent Brain Cognitive Development (ABCD) Study, a large U.S. longitudinal research project tracking brain development and health among children and adolescents. Their analysis included 8,957 participants, divided into two groups: 6,225 children who owned smartphones at age 12 (about 70% of the sample) and 2,732 who did not.
The researchers examined four categories of symptoms at ages 12 and 14: binge eating, compensatory behaviors intended to prevent weight gain, fear of gaining weight and the tendency to tie self-worth to body weight.
They did not investigate whether participants had been diagnosed with anorexia, bulimia or another eating disorder. Instead, they looked for symptoms and behaviors that can occur even without a formal diagnosis. Such symptoms, however, may still be associated with psychological distress and an increased risk of developing more serious problems later.
Two years later, the groups differed clearly. At age 14, nearly one in four adolescents who had owned a smartphone at age 12 (24.2%) reported at least one of the symptoms studied, compared with 15.5% of those who had not owned one.
To determine whether other differences between the groups might explain the findings, the researchers accounted for factors including gender, household income, parental education, body weight, pubertal development, symptoms of depression and attention-deficit/hyperactivity disorder, parental monitoring and ownership of other digital devices. They also accounted for disordered eating symptoms that were already present at age 12.
Even after these adjustments, smartphone ownership at age 12 was associated with a 49% higher risk of reporting at least one disordered eating symptom at age 14.
When the researchers examined individual symptoms, smartphone ownership at 12 was associated with a 67% higher risk of reporting binge eating two years later and a 50% higher risk of reporting compensatory behaviors intended to prevent weight gain. The risk of tying self-worth to body weight was approximately twice as high.
By contrast, the researchers found no statistically significant association between owning a smartphone at 12 and fear of gaining weight at 14.
When the screen moves from the living room to a child's pocket
The findings raise questions about the digital environment children enter when they receive their first smartphones.
Dr. Jason Nagata of the University of California, San Francisco, who led the study, told CNN that personal smartphone ownership changes the nature of children's access to digital content. “A smartphone can put a whole world of appearance-focused content in a young person’s pocket,” he said.
“When we talk about screen exposure, we generally mean it in a broad sense, but a smartphone is a little different,” said Shirel Tirosh, director of the eating disorders clinic operated by Israel's Maccabi Healthcare Services in Be'er Sheva.
“It belongs to the child personally, stays with them all the time and isn't part of a shared family screen,” she explained. “A child can take it into their bedroom alone, and even if they're sitting in the living room next to their parents, that doesn't mean the parents can see what they're watching.”
That, she said, is the most significant difference. “Parental oversight is much more limited. Children with smartphones are exposed earlier to very specific groups, including communities that encourage behaviors associated with anorexia and bulimia, as well as targeted advertising.”
This exposure occurs during an already sensitive developmental period. Their bodies are changing rapidly, social acceptance is becoming increasingly important, and adolescents are more inclined to compare themselves with others.
Shirel TiroshPhoto: Maccabi Healthcare ServicesThe researchers noted that repeated comparisons with idealized body images, including edited photographs, filtered pictures and sometimes AI-generated images, may contribute to body dissatisfaction.
They also highlighted so-called “fitspiration” content, which ostensibly promotes healthy living and fitness but has been linked in previous studies to appearance comparisons and body dissatisfaction, an established risk factor for disordered eating.
Perhaps the most significant change in recent years, however, is that children no longer need to actively search for the same type of content. Sometimes, simply pausing on a video is enough for the algorithm to take over.
“Algorithms today identify vulnerabilities, insecurities and areas where a child has shown even a momentary interest, and then repeatedly expose them to similar content,” Tirosh said.
“Previous studies have shown that on TikTok, for example, watching certain content for just a few seconds can be enough for the algorithm to identify an interest. Once that happens, the subject can become a target, and the app starts flooding the child with more videos about fitness, nutrition, weight loss and similar topics.”
This creates a gap between the power of the technology and children's ability to understand how it affects them.
“When we give this entire world to a child whose thinking and emotional regulation are still developing, we create potential risks,” she said. “We know from other research that within just a few clicks, children can reach content that is completely inappropriate for their age, including pornography. It's a world in which parents don't always understand how easy it is to get drawn in.”
The Israeli perspective
In Israel, another question arises: What happens when children receive smartphones long before the age examined in the study?
For many Israeli families, the first smartphone is no longer a bar or bat mitzvah gift. “Today in Israel, some children receive smartphones in first grade, or even at age five or six,” Tirosh said.
“Often, parents do this for very understandable reasons. A child needs to walk home from school alone, parents want to stay in touch, and there are also security concerns. But it means the exposure begins earlier.”
The current study does not establish what happens when children receive smartphones at those younger ages. Tirosh, however, said the effects of exposure to body image and appearance-related content are already apparent in her clinical work.
“We don't yet have research data on that, but clinically, we're seeing these things,” she said. “We ask patients at the clinic to open their phones and show us what appears in their feeds. We see what they're watching, and they still don't think critically enough about what they're being shown.”
Children, she explained, may not understand that a particular video or post is advertising, even when it is clearly marked as sponsored content. “That's something we work on with our patients.”
The problem is that children do not need to search TikTok for the word “diet” to encounter messages about weight. Such messages can appear during entirely unrelated online activities.
“Imagine a child reading an article that interests them on a news website,” Tirosh said. “As they scroll, an advertisement may appear that isn't appropriate for their age at all. It might talk about reducing belly fat, a supplement you add to coffee that supposedly 'melts' weight away, or repeatedly show images promoting the ideal of thinness.”
Over time, “children begin to internalize messages about how they should feel about their bodies and themselves,” she said.
An association, not necessarily a cause
These explanations suggest possible mechanisms behind the association identified by the researchers, but the study itself did not examine which apps participants used, what content they viewed or how much time they spent on their phones.
Despite its large sample and two-year follow-up, the research was observational. Children were not randomly assigned to receive smartphones or remain without them, so the findings cannot establish that smartphones themselves caused the symptoms.
'Children begin to internalize messages about how they should feel about their bodies and themselves'
(Photo: shutterstock)
Families that give their children smartphones at an early age may differ in other ways from those that delay the purchase, and even after statistical adjustments, not all potential differences can be ruled out.
The researchers identified factors that were not fully accounted for in the analysis, including bullying at school or online, neurodevelopmental conditions and other mental health problems. Reverse causation also cannot be entirely ruled out, meaning that a child's preexisting characteristics or difficulties may have influenced the parents' decision to give them a smartphone in the first place.
Nevertheless, the association persisted even after researchers accounted for disordered eating symptoms that were already present at age 12.
The authors said the findings justify further research into the possible mechanisms involved, including social media content, recommendation algorithms, disrupted sleep, private and unsupervised access, or a combination of factors.
What warning signs should parents look for?
Teenagers want privacy, and understandably so. But there may be a point at which a closed door, whether physical or digital, warrants closer parental attention. “In my approach, a child who absolutely refuses to let a parent touch their phone is a red flag,” Tirosh said.
“Obviously, adolescents want privacy, but when a child won't allow their parents to know anything about what's happening on their device, that's something that needs attention. Ultimately, we've given the child a tool that requires some degree of parental supervision.”
The phone itself, however, is only part of the picture. Sometimes the most important warning signs emerge when the screen is turned off.
“Children who withdraw and spend a lot of time alone in their rooms, children who start avoiding meals or reducing how much they eat, or when we begin hearing them express dislike or dissatisfaction with their bodies, these are things that should raise red flags for parents,” she said.
“It's also important to remember that children at these ages are more vulnerable to self-harm and suicidal behavior, and exposure to certain smartphone content may play a role there as well.”
Other warning signs include an increasing preoccupation with weight and calories, episodes of binge eating, or exercise driven by a perceived need to compensate for eating.
The study does not identify a particular age at which owning a smartphone suddenly becomes safe.
Nagata emphasized that the decision depends on the individual child and family, and that parents should remain involved in their children's digital lives when giving smartphones to younger children.
Professor Mitch Prinstein of the University of North Carolina's Department of Psychology and Neuroscience, who was not involved in the research, told CNN that parents should give their children access to social media gradually rather than moving abruptly from a completely restricted phone to a completely unrestricted device.
Encouraging healthier smartphone habits
For Tirosh, parental responsibility does not end with deciding whether to buy a child a smartphone. In many ways, it begins once the device is in the child's hands.
“Parents need to use parental control apps, block potentially problematic websites and pay attention to the age at which they allow access to social media,” she said.
“We're seeing the age of use getting younger. Ten-year-old girls are already making TikTok videos about skincare and beauty. Why does a 10-year-old girl need to make skincare videos? Personally, I can't understand it. We need to pay attention to what content we're allowing children to consume.”
Alongside parental controls, recommendations discussed in connection with the research include using age-appropriate apps, keeping phones out of bedrooms, establishing rules for phone use during meals and maintaining open conversations about the content children encounter online.
But screen time carries another cost that is easier to understand: Every hour spent on a phone is an hour not spent doing something else. “More screen time means fewer hours of social activity, less movement and less interaction with parents,” Tirosh said.
“These are things we very much want children to experience: talking to us, spending time outdoors, being physically active and interacting verbally with their peers.”
The COVID-19 pandemic, she added, significantly disrupted those patterns. “We saw its effects and how difficult it was afterward for some children to interact with others or communicate with their surroundings.”
Even if disconnecting children entirely from the digital world is unrealistic, parents can still create boundaries that give them some breathing room. One of the simplest places to start is the hour before bedtime.
The researchers also pointed to disrupted sleep as a possible link between smartphone use and disordered eating. Late-night phone use can interfere with sleep, potentially affecting the body's ability to regulate hunger and fullness while increasing emotional sensitivity. However, the study did not directly investigate this connection.
“Limiting screen time before bed is extremely important, but parents don't always give it enough attention,” Tirosh said. “Ideally, children should avoid screens for two hours before bedtime, though that may not always be realistic. At the very least, they should put away their smartphones, computers and televisions an hour before going to sleep.”
For Tirosh, the issue goes beyond how tired children may feel the next morning. “When a child's sleep is disrupted, they're less emotionally regulated the following day,” she said.
“Significant cognitive and developmental processes take place at these ages, so when sleep quality is repeatedly disrupted over time, the effects can be long-lasting.”