Impact of the COVID-19 pandemic on initial weight loss in a digital weight management program: A natural experiment

Objective The aim of this study was to assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on initial weight loss during a digital weight management program. Methods Participants (n = 866,192; BMI 33.6 [SD 7.4] kg/m(2)) who joined a digital weight management program (WW) in the first 30 weeks of 2020 (COVID-19 cohort) were compared with participants (n = 624,043; BMI 33.1 [SD 7.2] kg/m(2)) who joined the same program during the same time period in 2019 (control cohort). Weight change (percentage) and self-monitoring over the first 4 weeks of enrollment were compared between the cohorts. Significance was defined as meeting the criteria for a small effect (d >= 0.2). Results Over the 30-week enrollment period, the COVID-19 cohort experienced significantly less weight loss than the control cohort but only for 7 weeks of enrollments. The COVID-19 cohort also had fewer days of food tracking but only for 3 weeks of enrollments. There were no differences in the self-monitoring of weight and activity at any time between the two cohorts. Conclusions Over a 30-week enrollment period, COVID-19 had negative effects on both weight loss and food self-monitoring, but the effects were short-lived. Those participating in evidence-based weight management programs can expect similar levels of initial weight loss as those experienced before the pandemic.