A changed research landscape of youth's obesogenic behaviours and environments in the post-COVID-19 era.

The project 'Obesogenic Environment and Childhood Obesity' (OBECHO), carried out under the leadership of the International Institute of Spatial Lifecourse Epidemiology (ISLE), has reviewed all sufficiently reported studies of obesogenic environmental determinants published prior to 1 January 2019. Findings of the OBECHO project have formed the unprecedentedly inclusive evidence for policy-making and the establishment of the future research agenda regarding the obesogenic environment. Furthermore, the outbreak of the coronavirus disease 2019 (COVID-19) pandemic has made this evidence become an important benchmark record of how youths have interacted with the obesogenic environment in the pre-COVID-19 era. The implementation of lockdown measures worldwide for curbing COVID-19 transmission has been affecting not mere youth's lifestyle behaviours and weight status but, more fundamentally, obesogenic environments and hence youth-environment interaction patterns. However, COVID-19, although causing unfavoured changes, will speed up the transformation of the research landscape from traditional to modern modes for more reliable evidence. We should closely track and study those abnormalities caused by COVID-19 and the accompanying interventions.