Trajectories of BMI Before, During and Following the COVID-19 Pandemic among Participants in the MACS/WIHS Combined Cohort Study.

Introduction: Obesity is increasing across the US, with people with HIV experiencing greater risk of obesity-related adverse health outcomes including metabolic diseases. Weight gain has been shown during the widespread shutdowns during the COVID-19 pandemic. We examined weight trajectories before, during and after the COVID-19 pandemic among people with and without HIV.

Setting: Participants in the Multicenter AIDS Cohort Study-Women's Interagency HIV Study Combined Cohort Study (MWCCS).

Methods: Study time periods were: 1) Pre-pandemic period, May 15, 2018 through March 15, 2020; 2) Pandemic period, March 15, 2020 through September 30, 2021; and 3) Post-pandemic period, October 1, 2021 through September 30, 2024. A piecewise linear mixed effects regression model adjusted for baseline age was fitted with a random intercept for individual. Interaction terms examined differences by sociodemographic characteristics.

Result: Among 1,586 participants, 66.5% were living with HIV. From the pre- to during-pandemic period, there was a statistically significant 0.14 kg/m2/visit increase in BMI (95% CI:0.07. 0.22). There was a 0.3 kg/m2 reduction in mean BMI in the 36 months from pandemic [32 kg/m2 (SD: 8.6)] to post-pandemic [31.7 kg/m2 (SD: 8.5)] periods. Similar trajectories were noted among sociodemographically vulnerable subgroups.

Discussion: Contrary to our hypothesis, we observed a downward BMI trajectory back to baseline with the exception of those with residential instability in the post-COVID-19 pandemic period following a statistically significant weight gain during the pandemic. Understanding factors associated with decreasing BMI trajectories in the post-pandemic period is important in continuing to address the obesity epidemic in the U.S.