Comparing 2019 and 2021 high school students' dietary and physical activity behaviors 

Comparing 2019 and 2021 high school students dietary and physical activity behaviors | Image Credit: © Augustas Cetkauskas - © Augustas Cetkauskas - stock.adobe.com.

Physical activity and healthy dietary behaviors provide adolescents with various benefits and are important to public health strategies for chronic disease prevention, according to a recent CDC Morbidity and Mortality Weekly Report (MMWR). Compared to pre-COVID-19 (2019) data and 2021, the report demonstrates the need to increase healthy dietary and physical activity behaviors in both the recovery phase of COVID-19 and in the long term.

According to the MMWR, fall of 2021 was the first school semester with widespread in-person learning since the onset of the pandemic. To understand dietary and physical activity behaviors among adolescents during this time, the report used data from the 2021 national Youth Risk Behavior Survey (YRBS), conducted among a nationally representative sample of US public and private school students in grades 9 to 12. This was used to update estimates of dietary and physical activity behaviors among US high school students overall by sex and by race and ethnicity. The report provides a comparison between 2019 and 2021 behaviors for this population, which were examined.

According to the report, prior studies were conducted to examine dietary and physical activity behaviors of students between March of 2020 and July of 2021, but little was known about these respective behaviors among US high school students when a majority returned to school in the fall of 2021.

YRBS, a cross-sectional, school-based survey conducted biennially since 1991, was used for the report. Both 2019 (n = 13,677) and 2021 (n = 17,232) data was used in the report, which examined 6 dietary variables and 5 physical activity variables. Dietary variables included, during the 7 days before the survey, if students ate fruit or drunk 100% fruit juices less than 1 time per day, had eaten vegetables less than 1 time per day, had not eaten breakfast on all 7 days, had drunk soda 1 time or more per day (not counting diet soda), had drunk a sports drink 1 time or more per day, and had drunk less than 3 glasses of plan water per day.

During the 7 days before the survey, the physical activity variables included if students had been physically active for 60 minutes or more on all 7 days (federal guideline for aerobic activity), had exercised to strengthen or tone muscles 3 days or more (federal guideline for muscle-strengthening activity), met both aerobic and muscle-strengthening guidelines, had attended physical education class on all 5 days during a school week, and had played on 1 or more sports teams during the 12 months before the survey was conducted.

Students were classified into 7 racial and ethnic categories including American Indian or Alaska Native (AI/AN), Asian, Black or African American (Black), Hispanic or Latino (Hispanic), Native Hawaiian or other Pacific Islander (NH/OPI), White, and students who were two or more races (multiracial). For each behavior, the 2021 prevalence and 95% CIs were calculated overall and for each sex, and race and ethnicity group. Differences among prevalence estimates were considered statistically significant if the t-test p values were less than 0.05.

For dietary behaviors, 47.1% of students had eaten fruit or drunk 100% of fruit juices less than 1 time per day, while 45.3% had eaten vegetables less than 1 time per day. Of student data from 2021, 75.0% had not eaten breakfast daily, 14.7 had drunk sugar-sweetened soda 1 time per day or more, 11.2% drunk a sports drink 1 time per day or more, and 44.2% of students had drunk less than 3 glasses of plain water per day. From 2019 to 2021, 3 of the poor dietary behaviors examined increased.

For physical activity behaviors demonstrated in the report, 23.9% of students had been physically active for 60 minutes per day or more on all 7 days, while 44.9% had exercised to strengthen or tone their muscles 3 days a week or more. Of the students in 2021, 16.0% met both aerobic and muscle-strengthening guidelines, 19% attended physical education on all 5 days, and 49.1% had played on 1 or more sports teams.

The report results demonstrated decreases in both the prevalence of students who had attended physical education classes on all 5 days and students who had played on 1 or more sports teams from 2019 to 2021. No change in the prevalence estimates of having been physically active for 60 minutes or more per day on all 7 days or having met both aerobic and muscle-strengthening guidelines were observed. Overall, the study revealed none of the 11 behaviors examined improved since 2019, and certain dietary and physical activity behaviors worsened overall. Due to the association between poor dietary behaviors and insufficient physical activity and the several chronic health conditions and poor mental health, authors state these findings are particularly concerning.

According to the report, authors stated, “Health professionals, state and local health officials, policymakers, and school leaders can use the findings in this report to highlight the need for school health policies, practices, and programs that promote students’ healthy dietary and physical activity behaviors and their overall physical and mental health during immediate and longer-term pandemic recovery efforts.”

Reference:

Michael SL, Everett Jones S, Merlo C, et al. Dietary and physical activity behaviors in 2021 and changes from 2019 to 2021 among high school students — youth risk behavior survey, United States, 2021. MMWR Suppl. 2023;72. doi:10.15585/mmwr.su7201a9