Teens and smartphones: Study links increased use to weight gain, unhealthy diet

Seoul, South Korea — More hours of smartphone use – particularly for games and other entertainment – may lead teens to make unhealthy food choices and put on extra pounds, results of a recent study out of South Korea shows.

Using data from more than 53,000 adolescents in the Korea Youth Risk Behavior Web-Based Survey, researchers from Korea University looked at self-reported time spent on the phone, diet, weight and height. “Overweight” was defined as a body mass index in the 85th percentile or above for a person’s age, based on the 2017 Korean National Growth Charts.

The researchers looked at eight dietary factors, such as the number of times a week that fast food, fruits or vegetables were eaten. They found that more time spent on the phone – five-plus hours a day vs. two-plus hours a day – was “significantly associated” with higher intake of fast food, chips, and soda or other sugar-sweetened drinks. It also was linked to lower consumption of fruits and vegetables, along with skipping breakfast more often.

More importantly, longer duration of smartphone use was associated with a higher prevalence of 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,” study co-author Hannah Oh, an assistant professor at the university, said in an American Society of Nutrition press release. “Our data suggest that both smartphone usage time and content type may independently influence diet and obesity in adolescents.”

The participants who used their phones for information searching, however, reported healthier eating behaviors in general than those using their phones for gaming, browsing social media, messaging/chatting or streaming videos/music.

“Respondents who used their smartphone most frequently for gaming, video/music or webtoon/web-novel were more likely to be overweight or obese,” the study abstract states.

The study results were presented at Nutrition 2021 Live Online in June.