A Comparison of Changes in Health Behavior, Obesity, and Mental Health of Korean Adolescents Before and During the COVID-19 Pandemic: Online Cross-Sectional Study
Article information
Abstract
Objective
The health behavior and mental health problems of adolescents have shown a variety of changes due to the coronavirus disease-2019 (COVID-19) pandemic. This study compared health behavior, obesity, and mental health among Korean adolescents before and during the early COVID-19 pandemic.
Methods
Population-based and cross-sectional data from the 2019 and 2020 Korea Youth Risk Behavior Web-Based Surveys were used. Data of 57,048 and 54,948 adolescents from the 2019 and 2020 surveys, respectively, were compared. Multiple logistic regression analysis was conducted to compare health behavior, obesity, and mental health before and during the COVID-19 pandemic.
Results
The adjusted odds ratio (aOR) of overweight, obesity, and body image perceived subjectively as fat, were higher in the 2020 sample compared to the 2019 sample. The aOR of the frequency (more than 3 times a week) of fast-food consumption was higher in 2020 than in 2019. However, the aOR of physical activity, alcohol use, and smoking experience were lower in 2020 than in 2019. In addition, during COVID-19, adolescents were less likely to have perceived severe stress, depressive moods, and suicidal ideation.
Conclusion
Current evidence suggests the co-occurrence of positive and negative changes in health behavior, obesity, and mental health among Korean adolescents during the early COVID-19 pandemic. The results contribute insights for monitoring adolescents’ health behavior and promoting their mental health during school shutdowns.
INTRODUCTION
The coronavirus disease-2019 (COVID-19) pandemic has had a major impact on public health, the healthcare system, and our daily lives [1]. To avoid rapid spread of the virus, most countries imposed numerous nationwide measures, including social distancing requirements, closing of schools, and severe restrictions regarding socializing, exercise, and leaving the home [1,2]. Although adolescents are generally not at risk of developing severe COVID-19 [3], the effects of a lockdown may still severely affect adolescents due to the changes imposed on their normal daily routine [4].
Recently, the prevalence of cigarette smoking and alcohol consumption among Korean adolescents showed a decreasing trend, while the prevalence of obesity among adolescents showed an increasing trend before the 2020 COVID-19 pandemic [5]. However, the COVID-19 pandemic has had a substantial effect on the lifestyle behaviors across the world [6]. A noticeable decrease in physical activity during the pandemic had a negative effect on health behavior and increased the risk of weight gain and obesity in the youth [7]. Reduced opportunities for out-of-home activities among adolescents due to COVID-19 may lead to increased intake of high-calorie snacks and unhealthy foods and substance use [8,9]. Lifestyle and health-related behaviors during adolescence not only translate into the health-related behaviors of adults in the future, but also correlate to changes in the future disease burden [10].
Adolescents may be more susceptible to mental health impacts related to their vulnerable developmental stage, fear of infection, home confinement, suspension of regular school and extracurricular activities, and physical distancing mandates during the COVID-19 pandemic [11]. Adolescent mental health concerns in the United States have increased during the COVID-2019 pandemic. Meanwhile, adolescents in the United Kingdom, France, Canada, and the Netherlands, reported improved mental health in 2020 [5,12]. According to available data, Korean adolescents have experienced high rates of mental health problems, including suicidal ideation, suicide attempts, and self-injury, due to a number of factors, including academic pressure, social isolation, and cultural stigma surrounding mental health [13]. Despite the COVID-19 pandemic’s effect on daily life, limited research exists on mental health among Korean adolescents.
Korean government implemented infection control policies such as social distancing, travel restrictions, and quarantine to respond to the pandemic [4]. This included restrictions on school attendance and conducting online classes over a long period of time which have significantly changed adolescents’ daily lives [14]. Pandemic-associated negative impacts on adolescents’ mental health and health behaviors need to be monitored and addressed to mitigate short- and long-term impacts. Therefore, this study aimed to compare the changes in health behavior in the 2020 COVID-19 pandemic versus the 2019 pre-pandemic period. In addition, we compared the prevalence of depressive symptoms, suicidal ideation, and stress perception from a nationally representative health survey of Korean adolescents.
METHODS
Data and study population
Data were studied from the 2019 and 2020 Korea Youth Risk Behavior Web-Based Surveys (KYRBWS) [15], conducted annually by the Korea Disease Control and Prevention Agency. The KYRBWS is a structured, anonymous, and self-administered questionnaire with stratification, clustering, and multistage sampling research design [16].
Prior to conducting the cross-sectional KYRBWS survey, a sample school was selected, and teachers in charge of supporting the survey of the sample school were selected and educated. In addition, the teacher assigned one computer per student to the sample class in the computer room of the school where the Internet was available, and the seats were randomly assigned [15].
The 2019 KYBRWS conducted in June 2019, involved 57,048 adolescents from 400 middle schools and 400 high schools, whereas the 2020 KYRBWS conducted from August to November 2020 at 800 schools, involved 54,948 adolescents. In 2020, some schools, where there was difficulty with the questionnaire in the computer room due to COVID-19, conducted a survey in the classroom under the supervision of a teacher with a mobile device (tablet PC, smartphone). The final study sample comprised 111,996 adolescents.
Since the first confirmed case of COVID-19 in Korea was reported on January 20, 2020 [17], the 2019 KYRBWS data were considered pre-COVID-19 data. The participation rate was 95.3% in 2019 and 94.9% in 2020 [15].
Body mass index and body image perception variables
Self-reported height and weight were used to calculate body mass index (BMI), and the following criteria to classify obesity: underweight (<18.5 kg/m2), normal weight (<23 kg/m2), overweight (≥23 kg/m2), and obese (≥25 kg/m2) [4]. Body image perception was assessed by the following question: “In general, how do you perceive your body image?”. Possible responses were: “very thin,” “thin,” “normal,” “fat,” and “very fat.” Responses were reclassified into three groups: thin, normal, and fat due to small sample size. We cited a few previous studies to explain reclassification into three groups [18-21].
Health behavior variables
Frequency of carbonated beverages and fast-food consumption, physical activity, alcohol experience, and smoking experience were considered as behavior variables. The frequency of carbonated beverage consumption was assessed by the following question: “In the past 7 days, how often did you drink carbonated beverages (not carbonated water)?”. The frequency of fast-food consumption was assessed by the following question: “In the past 7 days, how often did you eat fast foods (e.g., pizza, hamburger, chicken)?”. Possible responses to both questions were: “no,” “1–2 times a week,” “3–4 times a week,” “5–6 times a week,” “once daily,” “twice daily,” and “3 or more times daily.” The responses were reorganized into three groups: no, 1–2 times a week, and more than 3 times a week. Physical activity was assessed by the following question: “In the past 7 days, on how many days did you perform more than 60 minutes of physical activity (of any type) that would cause you to run out of breath or increase your heart rate?”. Possible responses were: “no” or “from 1 to 7 days.” Analysis was carried out by reclassifying the responses into three groups: no, 1–2 days a week, and more than 3 days a week. Alcohol and smoking experiences were assessed by the following questions: “In the past 30 days, have you had more than one glass of alcohol to drink?” and “In the past 30 days, have you smoked at least one cigarette?”. Responses were either “yes” or “no.” [4,22,23]
Mental health variables
Perceived severe stress, depressive moods, and suicidal ideation were considered as mental health variables. Perceived severe stress was assessed by the question: “In general, how do you perceive your stress?”. Possible responses were: “very severe,” “severe,” “moderate,” “little,” and “never.” For analysis, we reclassified responses into two groups: yes (very severe, severe) and no (moderate, little, never) [24]. Depressive moods were assessed by the question: “In the past 12 months, have you ever felt sadness or despair that was sufficient to make you pause your daily activities for two whole weeks?”. Possible responses were: “yes” or “no.” Suicidal ideation was assessed by the question: “In the past 12 months, have you ever seriously considered suicide?”. Possible responses were: “yes” or “no.” [4,18,21]
Sociodemographic variables
The sociodemographic variables were sex, school grade, household income level, and self-reported academic achievement. School grade was classified from the 7th grade to 12th grade. Self-reported household income level was assessed through responses to: “What is your household income level?”. Possible responses were: “high,” “middle-high,” “middle,” “low-middle,” and “low.” For analysis the responses were reclassified into three groups: high, middle (middle-high and middle), and low (low-middle and low) levels. Self-reported academic achievement was assessed through responses to the question: “In the past 12 months, how has your average academic achievement been?”. Potential responses were: “high,” “middle-high,” “middle,” “middle-low,” and “low,” that were reclassified into three groups: high, middle (middle-high and middle), and low (low-middle and low) levels [18,22,23].
Statistical analyses
All statistical analyses were conducted considering the multistage cluster sampling design with the weighted values for each participant. Differences in BMI, body image perception, health behavior, and mental health between 2019 and 2020 were compared using the chi-square test.
Multivariate logistic regression was used to evaluate the association between BMI, body image perception, health behavior, and mental health. The odds ratio (OR) for BMI, body image perception, heatlh behavior, and mental health of the 2020 participants were compared with those of the 2019 participants, and the crude and adjusted OR (aOR) were also examined. For the OR of BMI, body image perception, and health behavior, the sociodemographic variables of sex, grade, academic achievement, and household income level were adjusted. For the mental health analysis, the sociodemographic variables in model 1, and the sociodemographic as well as BMI, body image perception, and health behavior variables in model 2 were adjusted. The statistical analyses were carried out using the IBM SPSS/WIN 25.0 program (IBM Co., Armonk, NY, USA). The statistical significance level was p<0.05.
Ethics statement
This study was a secondary analysis study using national statistical data, and no additional process for subject recruitment and consent was required. The study used de-identified data on the KYRBWS as a government-approved statistical survey (approval number: 117058).
This retrospective study was in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the Institutional Review Board (IRB) of the College of Medicine, The Catholic University of Korea (IRB approval number: MC22ZISI0048).
RESULTS
Table 1 shows the general characteristics of the 111,996 Korean adolescents. Overall, 57,048 adolescents in 2019 were compared with 54,948 adolescents in 2020. Compared to the 2019 sample, more adolescents in the 2020 sample had self-reported low academic achievement (2019: 31.8%; 2020: 33.0%). As regards BMI, overweight (2019: 12.6%; 2020: 13.6%) and obese (2019: 15.5%; 2020: 17.0%) adolescents’ levels were higher in 2020, compared to 2019. Alcohol experience (2019: 37.8%; 2020: 32.1%), smoking experience (2019: 12.4%; 2020: 10.2%), perceived severe stress (2019: 39.9%; 2020: 34.2%), depressive moods (2019: 28.0%; 2020: 25.2%), and suicidal ideation (2019: 13.1%; 2020: 10.9%) were all lower in 2020 compared to 2019. In the results of the chi-square test, statistically significant differences were found in all variables, except for sex, household income levels, and the frequency of fast-food consumption (p<0.001).
Characteristics of Korean adolescents before and during the early period of the COVID-19 pandemic
Table 2 describes the OR of BMI, body image perception, and health behavior for the early period of the COVID-19 pandemic compared to before the COVID-19 pandemic. Among adolescents, overweight (aOR: 1.155; 95% confidence interval [CI]: 1.076 to 1.240) and obesity (aOR: 1.190; 95% CI: 1.078 to 1.315) were higher in 2020 than in 2019. The OR of body image perceived subjectively as fat was higher in the 2020 than in the 2019 sample of adolescents (aOR: 1.156; 95% CI: 1.048 to 1.234). The frequency of fast-food consumption (more than 3 times a week) was 1.063 times higher in 2020 than in 2019. In 2020, adolescents’ aOR for the frequency of carbonated beverage consumption (1–2 times a week) was 0.855 times lower than in 2019. Physical activity was also lower in 2020 than in 2019. Likewise, alcohol experience (aOR: 0.790; 95% CI: 0.749 to 0.843) and smoking experience (aOR: 0.977; 95% CI: 0.906 to 0.998) were lower in 2020 than in 2019.
Odds ratio of health perception and behaviors for the early period of the COVID-19 pandemic compared to before the pandemic
Table 3 shows the OR of mental health for the early period of COVID-19 compared to before the COVID-19 pandemic. As a result of adjusting for variables, all the mental health variables in models 1 and 2 showed a low OR. According to the final model 2, adolescents were less likely to have perceived severe stress (aOR: 0.906; 95% CI: 0.876 to 0.937), depressive moods (aOR: 0.946; 95% CI: 0.914 to 0.979), and suicidal ideation (aOR: 0.884; 95% CI: 0.845 to 0.925) during COVID-19.
Odds ratio of mental health for the early period of the COVID-19 pandemic compared to before the pandemic
DISCUSSION
Our study found that overweight/obesity, body image perceived subjectively as fat, physical activity, and the frequency of fast-food consumption represented negative changes in the early COVID-19 pandemic, compared to before COVID-19. However, the alcohol/smoking experience, and mental health in adolescents showed positive changes in the early COVID-19 pandemic, compared to before COVID-19.
Physical activity was reduced in the 2020 adolescent sample compared with the 2019 adolescents. With school, sports, and recreation/gym facility closures due to COVID-19, declines in physical activity have been reported [25,26]. This reduction in activity may be even more pronounced for adolescents. Prior research exploring the relationship between age and physical activity in Canada and the United States found adolescents’ physical activity patterns to be more impacted by COVID-19 compared to physical activity of younger children [27]. It is well-established that physical activity is essential to improve and maintain physical and mental health. Measures and monitoring are needed to curb the decline in physical activity [28]. Youth with increased physical activity during the COVID-19 pandemic had higher resiliency scores and less reported depression than their counterparts who either had no change or decreased physical activity levels. It is notable that these are potentially modifiable factors that could be addressed through interventions [27].
To evaluate pandemic-related changes in weight in school-aged youths, we compared the BMI of adolescents during the pandemic in 2020 with before the pandemic in 2019. Consistent with previous studies, BMI of adolescents was negatively affected by the COVID-19 lockdown compared with before the COVID-19 lockdown [7,20,29]. Research should monitor whether the observed weight gain persists and what long-term health consequences may emerge.
Eating habit plays a crucial role in adolescents’ physical and mental development and the impacts might last until adulthood. Some previous research has found increased consumption of fast food among adolescents where there is a high density of fast food outlets located near schools and transport hubs [25]. Meanwhile, the reduced consumption of fast food was observed due to a decrease in opportunistic purchases of fast food during the day and traveling either to school or to work [20]. These findings suggest significant changes in the way communities currently function, especially for young people, might have simultaneously impacted health [29]. It is important to note that the impact of the pandemic on adolescents’ dietary behaviors can vary widely based on factors like cultural background, socioeconomic status, family dynamics, and personal preferences.
Our findings indicated that adolescents were less likely to report alcohol experience and smoking experience in the 2020 than in the 2019 [30,31]. Substance use may have decreased because of a greater difficulty in obtaining tobacco cigarettes, e-cigarettes, or alcohol [30,32,33]. This suggests an intimate link between substance use and availability. In addition, the relationship between friends’ substance use and personal substance use is strong. Remote classrooms limited peer interactions and provided opportunities for increased parental oversight of behavior patterns [34].
Adolescence is a time period during which rapid physical and mental development occurs, and adolescents are emotionally unstable and more sensitive to stress, emotional conflict, fear, and sudden changes in daily life compared to adults [14]. Therefore, adolescents may be more vulnerable to the mental health effects of the COVID-19 pandemic. Several studies have offered insight into the impact the pandemic has had on children and young people’s mental health, mostly reporting on its negative mental health consequences [13,35]. In fact, our study suggested that adolescents were less likely to have perceived severe stress, depressive moods, and suicidal ideation during the COVID-19 pandemic. Similarly, there was either no rise or fall in the suicide rates in Norway, England, and Japan in the early phase of the COVID-19 pandemic [36-38]. In addition, a recent study in Korea underlined that sadness or despair, levels of stress, and suicidal-related behaviors decreased among Korean adolescents in the early COVID-19 pandemic compared with those before the pandemic [39]. This might be because improved relationships with friends and family, less loneliness and exclusion, reduced bullying, better management of school tasks, and more sleep and exercise during lockdown [13].
This study has a few limitations. First, we examined changes in BMI, body image perception, behavior, and mental health during the first year of COVID-19. However, in our study, there was no variable on whether or not adolescents were positive for COVID-19 infection. Follow-up studies are needed to investigate health behaviors and mental health according to the prevalence of positive COVID-19 in adolescents. Second, we did not have any information regarding nutrients or total calories consumed. Information on in-depth health behavior, such as total calories and nutrients, can help evaluate the effect of COVID-19 on eating habits and obesity. Third, KYRBWS was conducted using a self-report questionnaire from students who may under- or over-report their behaviors or attitudes. Because of the limitations associated with self-report measures, objective or direct measures have been recommended to improve measurement precision [1]. However, KYRBWS is a survey with nationally representative samples of Korean school adolescents and has been conducting surveys annually with the same sampling frame, survey instruments, and methods. Therefore, data from the KYRBWS can be used to identify changes in mental health status after the pandemic COVID-19 compared with pre-pandemic status [16,40]. Fourth, depressive mood variables in this study were not diagnosed by clinicians using structured assessment tools. However, according to the Diagnostic and Statistical Manual of Mental Disorder-Fifth Edition, a depressive mood lasting for more than two weeks is one of the primary symptoms of major depressive disorder and could be used as a screening questionnaire for depressive disorder [41]. Finally, some variables may have been affected by seasonal variation. The KYRBWS was conducted from June to August before the COVID-19 pandemic (in 2019), whereas after the COVID-19 pandemic, the survey was conducted from August to November. This difference in the survey period may have affected some survey items that could be affected by seasonality, such as physical activity or carbohydrate drink.
Despite the above limitations, this study used a representative sample of the Korean adolescent population. It contributes by providing insights on monitoring health behavior and promoting mental health for adolescents during school shutdowns in consideration of the next infectious pandemic.
In conclusions, this cross-sectional study found that the co-occurrence of positive and negative changes in health behaviors and mental health among Korean adolescents during the early COVID-19 pandemic. Obesity and the frequency of fast-food consumption represented negative changes, compared to before COVID-19. However, the alcohol/smoking experience and mental health in adolescents showed positive changes. This study may help for policymakers and practitioners to effectively address and minimize adverse health impacts on health behavior and mental health among adolescents during the next infectious disease pandemic. Future studies may be needed to assess the long-term effects of changes in mental health and health-related behaviors during adolescence. This change can affect adult health behaviors and correlate with changes in future disease burden.
Notes
Availability of Data and Material
The data can be publicly downloaded at http://www.kdca.go.kr/yhs/ after entering basic personal details. We used the SPSS dataset of KYRBWS in 2019 and 2020. The authors do not possess the right to directly distribute the data.
Conflicts of Interest
The authors have no potential conflicts of interest to disclose.
Author Contributions
Conceptualization: Mi-Sun Lee, Hooyeon Lee. Data curation: Mi-Sun Lee. Formal analysis: Mi-Sun Lee. Funding acquisition: Hooyeon Lee. Investigation: Hooyeon Lee. Methodology: Mi-Sun Lee, Hooyeon Lee. Project administration: Hooyeon Lee. Resources: Mi-Sun Lee. Software: Mi-Sun Lee. Supervision: Hooyeon Lee. Validation: Mi-Sun Lee, Hooyeon Lee. Visualization: Mi-Sun Lee. Writing—original draft: Mi-Sun Lee. Writing—review & editing: Mi-Sun Lee, Hooyeon Lee.
Funding Statement
This study was supported by the National R&D Program for Cancer Control through the National Cancer Center (NCC) funded by the Ministry of Health & Welfare, Republic of Korea (Grant number: HA21C0225).