Combo of Low Screen Time, High Step Count Needed to Control BMI in Teens

WEDNESDAY, Feb. 15, 2023 (HealthDay News) -- The combination of low screen time and high step count is associated with lower body mass index (BMI) percentile in adolescents, according to a study published online Feb. 9 in JAMA Network Open.

Jason M. Nagata, M.D., from the University of California in San Francisco, and colleagues examined associations of physical activity and screen time with BMI among adolescents. The analysis included 5,797 U.S. adolescents (aged 10 to 14 years) participating in the Adolescent Brain Cognitive Development Study.

The researchers found that medium (four to eight hours; risk ratio, 1.24) and high (more than eight hours; risk ratio, 1.29) screen-time categories were associated with higher overweight or obesity risk versus low screen time (up to four hours). Similarly, medium (6,000 to 12,000 steps; risk ratio, 1.19) and low (<6,000 steps; risk ratio, 1.30) step-count categories were associated with higher overweight or obesity risk versus high step count (>12,000 steps). The investigators observed evidence of effect modification between screen time and step count for BMI percentile. Medium step count was associated with a 1.55 higher BMI percentile and low step count was associated with a 7.48 higher BMI percentile among adolescents with low screen use. Yet, among participants with high screen use, step-count categories did not significantly change the association with higher BMI percentile (low step count: 8.79 higher BMI percentile; medium step count: 8.76 higher BMI percentile; high step count: 8.26 higher BMI percentile).

"The results suggest that the combination of less than four hours per day of screen time and greater than 12,000 steps per day of physical activity is beneficial to minimize the risk of higher BMI percentile," the authors write.

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