Researchers uncover how SARS-CoV-2 exposure stabilizes BMI in adults, offering crucial insights into the pandemic’s lasting impact on weight and health disparities.

Study: Body mass index changes and their association with SARS-CoV-2 infection: a real-world analysis. Image Credit: New Africa / Shutterstock

A real-world study has explored the association between changes in body mass index (BMI) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among adults.

The study is published in the International Journal of Obesity.

Background

Real-world studies conducted throughout the coronavirus disease 2019 (COVID-19) pandemic have identified certain cardiometabolic health conditions, including obesity and diabetes, as significant risk factors for COVID-19 severity and mortality.

Studies involving long-COVID patients have indicated that SARS-CoV-2 infection can even worsen cardiometabolic health, as increased rates of diabetes, high blood pressure, and dyslipidemia have been observed among infected individuals.

Real-world evidence on the magnitude and direction of changes in cardiometabolic risk factors during the post-acute period of COVID-19 is particularly needed to understand the mechanisms by which SARS-CoV-2 infection increases the rates of cardiometabolic health conditions.

In this real-world study, scientists have compared the changes in BMI over time between individuals with and without SARS-CoV-2 infection as well as a pre-pandemic group of individuals who were age- and sex-matched to those who tested positive.   

Study design

The scientists analyzed patients’ real-world clinical and socio-demographic data, which was obtained from the OneFlorida and Clinical Research Network of the National Patient-Centered Clinical Research Network.

They compared the changes in BMI over a period of 100 days between an exposed cohort, a contemporary unexposed cohort, and an age- and sex-matched historical control cohort. The exposed cohort included adult individuals who tested positive for SARS-CoV-2 between March 2020 and January 2022. The unexposed cohort included adults who always tested negative for SARS-CoV-2 during the same period. The historical control cohort included adults who utilized the healthcare systems in the pre-pandemic period (March 2018–January 2020).

The study included age- and sex-matched individuals from the pre-pandemic period to characterize the differences in patient population attributable to the pandemic.

They retrieved participants’ BMI from objective measures of height and weight in electronic health records and explored the changes per 100 days of follow-up.

Important observations

A total of 249,743 adult individuals were included in the study. Of them, 19.2% were exposed, 61.5% were unexposed, and 19.3% were from the pre-pandemic period. The average age of the participants was 51 years.

Nearly 50% of the study population belonged to minority race and ethnicity groups, including non-Hispanic Black, Hispanic, and non-Hispanic Other. The average BMI of participants was 29.5 kg/m², with 30% and 40% being overweight and obese, respectively.

Changes in body mass index

The analysis controlling for potential confounding factors revealed that SARS-CoV-2-unexposed participants had lower BMI than exposed participants and higher BMI than Pre-pandemic (control) participants at the start of the follow-up.

The analysis of BMI changes per 100 days of follow-up revealed no change among exposed participants, a reduction among unexposed participants, and an increase among control participants.

The subgroup analysis considering sex, age, race and ethnicity, and hospitalization status revealed consistent differences in BMI at the start of the follow-up and over 100 days between exposed and unexposed participants across most socio-demographic subgroups, except for adult males and those aged 65 years and older. In these subgroups, a lower BMI was observed among exposed participants compared to that among unexposed participants.  

Study significance

This real-world study finds that adult individuals with SARS-CoV-2 exposure have higher body weight at the start of the post-acute phase of COVID-19 compared to contemporary individuals who are not exposed to the virus, as well as age- and sex-matched individuals from the pre-pandemic period.

Over the 100 days of follow-up, BMI remained stable for exposed individuals, whereas unexposed and pre-pandemic control individuals experienced a reduction and an increase in BMI, respectively.

The observed associations between SARS-CoV-2 exposure and BMI changes were present among racial and ethnic minorities and young adults who were disproportionately affected by COVID-19.

The higher BMI observed among SARS-CoV-2-exposed individuals suggests that they may have been at a higher risk of severe COVID-19 when seeking care, consistent with previous findings that elevated BMI is a risk factor for severe COVID-19.

An overall induction in BMI and obesity prevalence has been observed during the COVID-19 pandemic. This could be attributed to pandemic-related movement restrictions, a rise in sedentary time and unhealthy food habits, and disruption of preventive care.

Such bidirectional association between SARS-CoV-2 infection and cardiometabolic health conditions might be mediated by excess adiposity, insulin resistance, inflammation, or delayed recovery after COVID-19.     

Further studies are required to understand the mechanisms driving this observed increase in weight retention after SARS-CoV-2 infection. Ongoing studies involving long-COVID patients should focus on BMI trajectories to more conclusively understand the causative association between SARS-CoV-2 exposure and weight retention in adult individuals.