Changes in obesity and waist circumference in children and parents during the COVID-19 pandemic.

The COVID-19 pandemic disrupted daily behaviours. We compared the annual change in obesity prevalence before and during the pandemic in children and parents. Participants were recruited from TARGet Kids! in Canada and followed prospectively. Each participant had at least one body mass index (BMI) measure before and during the pandemic. Marginal logistic models with piecewise functions were used to estimate adjusted odds ratios (aORs) for the association between year and obesity prevalence before (2015-2020) and during the pandemic (2020-2023). Among children (n = 1,163), in the 5 years pre-pandemic, the average annual increase in the odds of obesity was 18% per year (aOR = 1.18, 95%CI 1.02-1.36).This increased substantially early in the pandemic (aOR = 2.17, 95%CI 1.45-3.25), and during the second year of the pandemic it decreased (aOR = 0.66, 95%CI 0.46-0.93). Among parents (n = 653), pre-pandemic there was an annual increase in the odds of obesity (aOR = 1.27, 95%CI 1.12-1.42) but this plateaued during the early (aOR = 0.79, 95%CI 0.50-1.25) and later pandemic periods (aOR = 1.08, 95% CI:0.81-1.43). Increases in child obesity during the pandemic were greatest among lower income families and younger children. Obesity prevalence among children rose significantly early in the COVID-19 pandemic and waned in the second year but remained higher than pre-pandemic levels.Clinical Trial Registration: www.clinicaltrials.gov , ID NCT01869530.