Seven hours a day on a phone correlates with disordered eating - even without an eating disorder diagnosis

Before smartphones, the relationship between screens and body image was already complicated. Television, magazines, and early internet research all pointed to links between media exposure and eating concerns. But smartphones are different. They are constant companions, delivering a personalized stream of content directly calibrated to hold attention - including images of idealized bodies, food content, and social comparison cues.

A systematic review published in the Journal of Medical Internet Research by researchers at King's College London now quantifies what many clinicians have suspected: problematic smartphone use (PSU) - a pattern of behavioral or psychological reliance on the device - is consistently associated with disordered eating symptoms in young people who have no diagnosis of an eating disorder.

What the data show

The review analyzed 35 studies from around the world, covering 52,584 participants with an average age of 17. The researchers, led by first author Johanna Keeler and senior author Ben Carter, professor of medical statistics at King's Institute of Psychiatry, Psychology and Neuroscience (IoPPN), found that higher daily smartphone use was associated with greater food addiction symptoms, broader disordered eating behaviors including uncontrolled eating and emotional overeating, and body dissatisfaction.

The association was particularly strong in those using their phones for more than seven hours a day.

An important distinction: this is about problematic smartphone use as a behavioral pattern, not simply screen time. PSU encompasses compulsive checking, difficulty disengaging, anxiety when separated from the device, and interference with daily functioning. It is not the same as smartphone addiction - a term the researchers explicitly caution against, noting that considerably more research is needed before that label applies.

Adolescence as a vulnerable window

Keeler points to developmental timing as a key factor. Adolescence is a period when individuals are actively constructing their sense of self, often by observing and comparing themselves to others. Smartphones provide an unprecedented volume of comparison material - much of it filtered, edited, and curated to present idealized appearances.

Consistent exposure to these images can lead to appearance dissatisfaction and poor self-esteem, both recognized risk factors for developing an eating disorder. The smartphone does not cause the eating disorder. But it may create or intensify the psychological conditions that make one more likely.

Correlation, not causation

The review is observational. It cannot establish that smartphone use causes disordered eating - only that the two co-occur with notable consistency across 35 independent studies. The direction of the relationship could run either way: people with existing body image concerns might use their phones more, not less, as a coping mechanism or source of validation. Or both smartphone overuse and disordered eating might share a common underlying driver, such as anxiety or low self-regulation.

The studies also varied substantially in methodology. Some measured screen time through self-report, which is notoriously unreliable. Others used different scales for problematic use. The 35 studies spanned multiple countries and cultural contexts, which adds generalizability but also introduces confounding variables that the review could not fully control.

Sample sizes were large in aggregate (52,584 participants) but individual studies ranged widely. And the average age of 17 means the findings may not apply equally to younger children or older adults.

What this means for intervention

The researchers argue their findings highlight the need for early intervention strategies that specifically address excessive phone use in young people showing signs of disordered eating. Current clinical frameworks for eating disorders tend to focus on body image, food behaviors, and psychological comorbidities. Smartphone use rarely features as a standalone intervention target.

That may need to change - not because the phone is the cause, but because it may be a modifiable risk factor. Reducing time on appearance-focused content, building awareness of social comparison behaviors, and developing healthier digital habits could complement existing therapeutic approaches.

Carter noted that the findings apply even to people without a formal eating disorder diagnosis, suggesting that the subclinical population - those with disordered eating behaviors that do not meet full diagnostic criteria - may be larger and more affected than previously recognized.