Smartphone Use Associated With Poor Diet, Overweight in Teens

Even moderate smartphone use may influence teens’ diet and weight, according to a new study of more than 53,000 Korean adolescents. Teens who used a smartphone for more than two hours per day were significantly more likely to eat more junk food and fewer fruits and vegetables than those spending less time on their phone. Teens spending more than three hours per day on a smartphone were significantly more likely to have overweight or obesity.

“While earlier studies have shown that TV watching is an important factor that increases the risk of obesity in children and adolescents, little is known about the effects of modern screen time such as smartphone use on diet and obesity,” says senior study author Hannah Oh, ScD, an assistant professor at Korea University. “Our data suggest that both smartphone usage time and content type may independently influence diet and obesity in adolescents.”

Childhood obesity is becoming more prevalent in many countries, including Korea and the United States. Children with obesity are more likely to have obesity as adults and face a higher risk of heart disease, diabetes, and other health problems.

Seaun Ryu, a master’s student at Korea University and the study’s first author, presented the research at NUTRITION 2021 LIVE ONLINE.

The researchers analyzed data from the Korea Youth Risk Behavior Web-Based Survey, a nationally representative sample of more than 53,000 Korean adolescents aged 12 to 18. After accounting for variables such as socioeconomic status that may influence obesity and smartphone ownership, the researchers examined the prevalence of which participants engaged in healthful behaviors (eg, eating fruits and vegetables) and unhealthful behaviors (eg, skipping breakfast and consuming fast food, chips, instant noodles, or carbonated or sweetened beverages) relative to the amount of daily smartphone use and the types of content used.

The prevalence of unhealthful behaviors and overweight rose with increasing daily smartphone use. Teens spending five or more hours per day on their phone were more likely to report consuming carbonated and noncarbonated sugar-sweetened beverages, fast food, chips, and instant noodles compared with those spending less than two hours per day on their phone.

Teens who reported using their phones more for information search and retrieval overall had more healthful eating behaviors than those using their phones more for chatting/messenger, gaming, video/music, and social networks. Respondents who used their smartphone most frequently for gaming, video/music, or reading comic books and fiction were more likely to have overweight or obesity.

Oh says potential drivers behind these trends could include exposure to food marketing in digital spaces, an increased propensity toward “mindless” eating while using a smartphone, inadequate sleep, or the displacement of time that would otherwise be spent on physical activity. She stresses the need to monitor food marketing targeting adolescents in digital media and, if warranted, work to prevent teens from being exposed to aggressive marketing or misleading messages about unhealthful foods. On the flip side, she notes that smartphones could be leveraged to improve public health through nutrition-tracking apps or by using digital platforms to make information about healthful eating more accessible.

“Adolescents of today are digital natives, who have grown up in close contact with digital devices such as smartphones, and thus are likely to be heavily influenced by them,” Oh and Ryu say. “Efforts should be taken to maximize the positive effects and minimize the negative effects of smartphone use on adolescent health.”

The researchers caution that the study wasn't designed to determine the temporal relationship between obesity and smartphone use; a longitudinal, prospective study would be needed to assess changes in body weight and smartphone use over time.

— Source: American Society for Nutrition