Evidence on the COVID-19 pandemic's impact on health behaviors is limited. This retrospective longitudinal study of UK and US adults (ZOE COVID Study) analyzed diet and lifestyle data pre- and peri-pandemic, using a bidirectional health behavior disruption index. Disruption was higher in younger, female, and socioeconomically deprived participants. Greater disruption correlated with more weight loss, but also more variable weight changes. Individuals with less healthy pre-pandemic habits improved diet quality and weight more than those with healthier pre-pandemic habits, regardless of deprivation. Public health policies should prioritize diet and physical activity for all, with targeted support for younger females and those in deprived areas.

Mohsen Mazidi, Emily R. Leeming, Jordi Merino, Long H. Nguyen, Somesh Selvachandran, Joan Capdavila Pujal, Tyler Maher, Kirstin Kade, Benjamin Murray, Mark S. Graham, Carole H. Sudre, Jonathan Wolf, Christina Hu, David A. Drew, Claire J. Steves, Sebastien Ourselin, Christopher Gardner, Tim D. Spector, Andrew T. Chan, Paul W. Franks, Rachel Gibson, Sarah E. Berry