Impact of the COVID-19 pandemic on obesity: a prospective cohort study of the Canadian Longitudinal Study on Aging (CLSA)

Objectives To examine the impact of the COVID-19 pandemic on body mass index (BMI) and obesity status among Canadian residents and explore how this association varied by sociodemographic and health status. Participants 41 302 adults, aged 45–85 at baseline, participating in the Canadian Longitudinal Study on Aging.

Primary and secondary outcomes BMI and BMI-defined obesity were measured at baseline, follow-up 1 and follow-up 2 (FUP2), with 33% of FUP2 data (n=13 444) gathered after 16 March 2020, when COVID-19 restrictions began. Correction factors were applied for self-reported BMI and weighted generalised estimating equations assessed BMI changes before and during the pandemic.

Results We found a significant interaction between follow-up time and timing of FUP2 data collection (before or during the pandemic). Participants measured during the pandemic had an excess BMI increase of 0.21 kg/m² (95% CI 0.15 to 0.28) and 1.06 times higher odds of obesity (95% CI 1.03 to 1.09) compared with prepandemic trends.

Increases were more pronounced among females, middle-aged adults and those without diabetes.