Impact of COVID-19 pandemic on weight and BMI among UK adults: a longitudinal analysis of data from the HEBECO study

BackgroundCOVID-19-related restrictions impacted weight and weight-related factors during the initial months of the pandemic. However, longitudinal analyses are scarce. MethodsAn online, longitudinal study was conducted among self-selected UK adults (n=1,818), involving three surveys during 2020 (May-June, August-September, November-December), covering height, weight and sociodemographic, COVID-19-related and behavioural measures. Data were analysed using generalised estimating equations. ResultsSelf-reported average weight and body mass index (BMI) significantly increased from May-June to August-September (74.95kg to 75.33kg, 26.22kg/m2 to 26.36kg/m2, both p<0.001), and then significantly decreased to November-December (to 75.06kg, 26.27kg/m2, both p<0.01), comparable to May-June levels (p=0.274/0.204). However, there was great interindividual variation, with 37.0%/26.7% reporting an increase and 34.5%/26.3% reporting a decrease in weight/BMI greater than 0.5kg/0.5kg/m2, respectively from May-June to November-December. The average weight/BMI increase was 3.64kg (95% confidence interval: 3.32,3.97)/1.64kg/m2 (1.49,1.79), and the average weight/BMI decrease was 3.59kg (3.34,3.85)/1.53kg/m2 (1.42,1.63). In fully adjusted models, increase in weight/BMI across surveys was significantly negatively associated with initial BMI, and positively associated with monthly high fat, salt and sugar (HFSS) snacks intake and alcohol consumption, and for BMI only, older age. However, associations were time-varying, such that lower initial BMI, higher HFSS snacks intake and high-risk alcohol consumption were associated with maintenance of increased weight/BMI from August-September to November-December. ConclusionThe average weight/BMI of UK adults increased during the early pandemic months, before returning to baseline levels in November-December 2020. However, this masks substantial interindividual variation in weight/BMI trajectories, indicating vulnerabilities associated with changes in food and alcohol consumption throughout the pandemic. What is currently known from previous studiesO_LISmall increases in average weight/BMI have been reported (1.57kg/0.31kg/m2) during the initial three months of the pandemic. C_LIO_LIChanges in weight/BMI during the early months were not uniform, with significant proportions increasing (11.2-72.4%) as well as decreasing (7.2-51.4%) weight/BMI. C_LIO_LIWeight/BMI change has been associated with several sociodemographic, lifestyle and behavioural factors. C_LIO_LIWhether these weight/BMI changes persist over longer durations of the pandemic, and the factors associated with any long-term weight/BMI change is largely unknown. C_LI What this paper addsO_LIIn UK adults, average weight/BMI first increased and then decreased from May to December 2020 during the pandemic, but this masks large interindividual variability in average changes. C_LIO_LIInitial BMI at the start of the pandemic and health behavioural factors such as alcohol consumption and high fat, salt and sugar (HFSS) snacks intake were significantly associated with a change in weight/BMI. C_LIO_LIThe strength of the association of alcohol consumption, initial BMI and HFSS snacks intake with weight/BMI change was dependent on the stage of the pandemic, with more pronounced differences becoming apparent during the latter part of 2020. C_LI