Less breakfast, more sugar and an introduction to tobacco: The unhealthy trends of transitioning to high school

Unhealthy behaviors became more common among adolescents as they advanced from elementary school to their final year of high school, with more students skipping breakfast, drinking sugary beverages and using multiple tobacco products, a government survey showed Monday.

Girls were also found to be more vulnerable than boys to mental health problems and smartphone overdependence.

The Korea Disease Control and Prevention Agency (KDCA) released data from the first seven rounds of its youth health survey, which tracked the same students from their final year of elementary school in 2019 through their third year of high school in 2025.

The project began in 2019 with a nationwide panel of 5,051 sixth graders and will follow their smoking, drinking, eating and other health habits through 2028. Last year’s survey of third-year high school students covered 3,756 students who participated in all seven rounds.

The current tobacco product use rate, defined as the percentage who used a tobacco product at least once during the previous 30 days, reached 5.3 percent among third-year high school students. That was up 5.29 percentage points from just 0.01 percent when they were in sixth grade.

Among third-year high school students, 4.41 percent currently smoked conventional cigarettes, 3.61 percent used liquid-based e-cigarettes and 1.59 percent used heated tobacco products.

Notably, the share of third-year high school students using two or all three types of tobacco products was far higher than the share using just one.

“The high rate of multiple tobacco product use means nicotine addiction among adolescents has grown more serious than before,” said Lee Sung-kyu, director of the Korea Center for Tobacco Control Research and Education. “That makes quitting harder and will inevitably hurt smoking rates 10 or 20 years from now. Smoking cessation policy needs a fundamental overhaul, including letting adolescents use cessation aids.”

Dietary habits also deteriorated as students moved through school. The proportion who skipped breakfast at least five days a week rose 14.9 percentage points, from 17.9 percent in sixth grade to 32.8 percent among third-year high school students.

The share who drank sugary beverages at least three times a week climbed from 50.9 percent to 60.9 percent over the same span. By contrast, the share eating vegetables at least three times a day fell 12.4 percentage points, from 18 percent to 5.6 percent.

Physical activity followed a similar downward trend even as students' bodies kept growing. Just 11.4 percent of third-year high school students got at least 60 minutes of physical activity on five or more days a week, less than half the 29.8 percent recorded in sixth grade.

Mental health and smartphone use showed clear gaps between boys and girls. Among third-year high school students, 8.3 percent had experienced moderate or severe generalized anxiety disorder, characterized by excessive tension or psychological anxiety. The rate among girls was 11.4 percent, 2.2 times the 5.3 percent recorded among boys.

Nearly one in three third-year high school students, or 31.9 percent, were at risk of smartphone overdependence. The rate was 35.2 percent among girls, over 1.2 times the 28.8 percent among boys.

“The findings are a public health warning that students’ overall health behaviors are gradually worsening in an academically focused environment,” KDCA Commissioner Lim Seung-kwan said. “There is an urgent need for tailored adolescent health policies, including smoking and drinking prevention programs differentiated by grade and measures to address emerging risks like digital overdependence.”

BY JUNG JONG-HOON [[email protected]]