Being physically active as a teen doesn’t necessarily guarantee an escape from the risk of obesity, especially if you spend so much time in front of screens, according to a new study.

The study, which was published in the journal JAMA Network Open, found that teenagers who spent more than eight hours a day in front of screens, regardless of their physical activity levels, were more likely to be at risk of obesity. In turn, they found that higher levels of physical activity among teens did not lower the risk of being obese or overweight if they also spent so much time in front of screens.

The Physical Activity Guidelines for Americans recommend 60 minutes of moderate-to-vigorous intensity exercise per day for American adolescents. However, less than 25 percent of teens meet these guidelines. According to the researchers, this reduction in physical activity has been followed by an increase in recreational screen use time, nearly tripling in the past few years.

Lead study author Jason Nagata and his colleagues looked at data from the Adolescent Brain Cognitive Development (ABCD) study, analyzed from July 8 to December 20, 2022. They involved a total of 5,797 adolescents who were between the ages of 10 and 14 years for their study.

To gather data on the adolescent’s screen time, the team asked them questions concerning the number of hours they spend per weekday or weekend on numerous types of media, including TV shows and movies, video, social media, video games, video chat, and so on.

Next, the researchers grouped screen time into 3 different categories: those who spent 0 hours to 4 hours each day as “low,” those with more than 4 hours to 8 hours each day as “medium,” and those clocking more than 8 hours each day in front of a screen as “high.”

Participants were then given a wearable digital device to wear for three weeks, where they measured the number of daily steps to gather data on the adolescent’s accumulated physical activity. 

Finally, they grouped the total steps covered each day into three categories: 1,000 steps to 6,000 steps daily as low, more than 6,000 steps to 12,000 steps daily as medium, and more than 12,000 steps daily as high.

From their reports, the teenagers had an average screen time of up to seven hours each day and an overall average step count of 9,246 steps per day over the 21-day period. Results from the study showed that higher levels of physical activity did not reduce the risk of being obese or overweight among those who spent all day looking at screens. In the same way, lower screen time did not offset the risk of obesity among those who were less physically active. 

According to the study authors, spending all day looking at screens is mostly sedentary behavior, which could cause one to eat more junk food, thereby consuming more calories. Plus, it takes away the time they’re supposed to engage in more important activities such as exercise, sleep, and socialization.

Another study by the same team, which followed 7,105 adolescents for 24 years, also found that teens who got too much screen time had higher risks of obesity, diabetes, and abdominal obesity 24 years later.

“Parents should have regular conversations with their children about screen use and discourage excessive time spent on screens,” said Prof. J. Nagata. “They could encourage screen-free time before bedtime or during family meals. Parents can also act as role models for their children with their own screen time and physical activity.” 

In conclusion, the researchers suggest that limiting screen time to less than four hours a day and getting more exercise is beneficial to reduce the risk of being obese or overweight.

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