Association of Changes in Obesity Prevalence With the COVID-19 Pandemic in Youth in Massachusetts

The COVID-19 pandemic and its social stressors have hindered obesity prevention and management. Obesity prevalence has been rising in the US, particularly in Black and Mexican American adolescents.¹ Few population-level studies have examined the effects of COVID-19 on childhood obesity prevalence. An observational study found childhood obesity prevalence in the Philadelphia, Pennsylvania, region increased from 13.7% to 15.4% (2019-2020).² The study included all patient visits and analyzed 2 time periods without a control period. Given obesity prevalence had been increasing prior to COVID-19, the observed increase may be overstated.¹ Using the Massachusetts Department of Public Health’s disease surveillance system (MDPHnet), we examined obesity prevalence in 3 periods from 2018 to 2020 in a fixed cohort of children and adolescents.

MPDHnet allows authorized users to query the electronic health record systems of 3 practice groups across 59 sites in Massachusetts serving 1.5 million socioeconomically diverse patients.³ We identified a cohort of individuals aged 2 to 17 years in 2018, with body mass index (BMI) measured from July 1 to December 31, 2018 (historical control period), July 1 to December 31, 2019 (pre–COVID-19), and July 1 to December 31, 2020 (post–COVID-19 initial surge). We assessed obesity prevalence (BMI ≥95th percentile per standardized growth charts⁴) overall and by sex, age (2-5 years, 6-11 years, 12-20 years) at time of BMI measurement, and race and ethnicity (Asian, Black, Hispanic, White). Race and ethnicity were reported by parents/guardians and captured in each practice’s electronic health record (eMethods in the Supplement). We calculated differences in trends by subtracting change in obesity prevalence pre–COVID-19 (2018-2019) from the change post–COVID-19 initial surge (2019-2020). Our study did not meet criteria for human subjects research by Massachusetts General Hospital’s institutional review board.

Among 46 151 included participants, 4197 (9%) were Asian; 4582 (10%), Black; 5862 (13%), Hispanic; 46 (0.1%), Native American; 24 751 (54%) White; and 6713 (15%), unknown race and ethnicity (Table 1). Obesity prevalence increased during 2019 to 2020 to a greater extent than expected based on the increase in pre–COVID-19 years, from 15.1% in 2018 to 15.7% in 2019 and 17.3% in 2020 (differences in trends, 1.1%; 95% CI 0.3%-1.9%). There were greater than expected increases in obesity prevalence among boys aged 6 to 11 years overall (2.8%; 95% CI, 0.8%-4.8%), specifically in Black (6.3%; 95% CI, –1.0%-13.6%) and Hispanic (7.1%; 95% CI, 0.1%-14.1%) subgroups, although the former had a wider 95% CI that crossed the null (Table 2).

Although childhood obesity prevalence was rising prior to COVID-19, the prevalence increased by a greater difference in Massachusetts youth during the COVID-19 pandemic. Our overall findings coincide with recent studies by the US Centers for Disease Control and Prevention and Kaiser Permanente, which found higher increases in obesity prevalence and BMI during COVID-19 vs before COVID-19, although they did not analyze subgroups by race and ethnicity.^5,6 Consistent with the study by Jenssen et al,² we observed greater increases in obesity prevalence during the COVID-19 pandemic in Black and Hispanic youth, particularly in boys aged 6 to 11 years.

We expect minimal residual confounding as we followed the same cohort from 2018 to 2020. We accounted for changes to health care utilization due to COVID-19 by requiring our cohort to have BMI measured in each period studied. However, our findings may not be generalizable to populations from different settings because this study was limited to individuals who sought in-person care during the COVID-19 pandemic from 3 Massachusetts practice groups.

COVID-19 has exposed and magnified health disparities, which will persist beyond the pandemic unless targeted obesity prevention and management policies and initiatives are implemented. Our findings beg further research to disentangle the structural and social factors, including the effects of racism, that influence rising childhood obesity prevalence surrounding the COVID-19 pandemic and support the need for dedicated measures to counteract the pandemic’s impact on obesity.

Corresponding Author: Allison J. Wu, MD, Division of Gastroenterology, Hepatology and Nutrition, 300 Longwood Ave, Hunnewell Ground Floor, Boston Children’s Hospital, Boston, MA 02115 (allison.wu@childrens.harvard.edu).

Accepted for Publication: October 3, 2021.

Published Online: December 13, 2021. doi:10.1001/jamapediatrics.2021.5095

Author Contributions: Dr Wu and Ms Rocchio had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Wu, Aris, Hivert, Klompas, Taveras.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Wu.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Wu, Aris.

Obtained funding: Wu.

Administrative, technical, or material support: Rocchio.

Supervision: Wu, Aris, Hivert, Klompas, Taveras.

Conflict of Interest Disclosures: Dr Wu reported grants from the Agency for Healthcare Research and Quality during the conduct of the study. Dr Klompas reported grants from Massachusetts Department of Public Health and the US Centers for Disease Control and Prevention during the conduct of the study. No other disclosures were reported.

Funding/Support: This study was funded by the Agency for Healthcare Research and Quality (grant T32HS000063).

Role of the Funder/Sponsor: The Agency for Healthcare Research and Quality had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Contributions: The authors wish to acknowledge Alex Gitungano, MPH, from the Massachusetts Department of Public Health, as well as the MPDHnet advisory panel, including Myfanwy Callahan, MD, MPH, from Atrius Health; Brian Herrick, MD, and Michelle Weiss, MPH, from the Cambridge Health Alliance; and Marlene Abreu, MA, and Lynette Mascioli, MPH, from the Massachusetts League of Community Health Centers. The authors also thank Aileen Ochoa, MPH, from Harvard Medical School and Harvard Pilgrim Health Care Institute. No compensation was received.