Diet and physical activity during the coronavirus disease 2019 (COVID-19) lockdown (March-May 2020): results from the French NutriNet-Santé cohort study

Abstract

Background: Since December 2019, coronavirus disease 2019 (COVID-19) has been spreading steadily, resulting in overwhelmed health-care systems and numerous deaths worldwide. To counter these outcomes, many countries, including France, put in place strict lockdown measures, requiring the temporary closure of all but essential places and causing an unprecedented disruption of daily life.

Objectives: Our objective was to explore potential changes in dietary intake, physical activity, body weight, and food supply during the COVID-19 lockdown and how these differed according to individual characteristics.

Methods: The analyses included 37,252 adults from the French web-based NutriNet-Santé cohort who completed lockdown-specific questionnaires in April-May 2020. Nutrition-related changes and their sociodemographic, lifestyle, and health-status correlates were investigated using multivariable logistic regression models. Clusters of participants were defined using an ascending hierarchical classification of change profiles derived from multiple correspondence analyses.

Results: During the lockdown, trends of unfavorable changes were observed: decreased physical activity (reported by 53% of the participants), increased sedentary time (reported by 63%), increased snacking, decreased consumption of fresh food (especially fruit and fish), and increased consumption of sweets, cookies, and cakes. Yet, the opposite trends were also observed: increased home cooking (reported by 40%) and increased physical activity (reported by 19%). Additionally, 35% of the participants gained weight (mean weight gain in these individuals, 1.8 kg ± SD 1.3 kg) and 23% lost weight (2 kg ± SD 1.4 kg weight loss). All of these trends displayed associations with various individual characteristics.

Conclusions: These results suggest that nutrition-related changes occurred during the lockdown in both unfavorable and favorable directions. The observed unfavorable changes should be considered in the event of a future lockdown, and should also be monitored to prevent an increase in the nutrition-related burden of disease, should these diet/physical activity changes be maintained in the long run. Understanding the favorable changes may help extend them on a broader scale. This trial was registered at clinicaltrials.gov as NCT03335644.

Keywords: COVID-19 lockdown; body weight; cohort study; diet; nutrition; physical activity; sedentariness.

FIGURE 1

Modifications in the consumption of major food groups during lockdown, NutriNet-Santé cohort study (n = 37,252), March–May 2020. Bars indicate the percentage of participants who reported having increased or decreased the consumption of the food group of interest during lockdown (corresponding number shown on the respective bars); darker colors represent percentages above 15% and/or a difference of percentages between those who increased and those who decreased of more than 10%. The 95% CIs are displayed at the extremity of the bars.

FIGURE 2

Dietary intakes reported in the month of April from 2017 to 2020, NutriNet-Santé cohort study, France, March–May 2020. Quantitative dietary intakes reported in April 2020 (via 24-hour dietary records completed during the lockdown; n = 10,617) and during the month of April over the past 3 years (repeated 24-hour dietary records completed in 2017: n = 1264; 2018: n = 1075; and 2019: n = 991), shown as mean values (diamond) and 95% CIs (vertical bar). P values from Student paired t-tests are provided for the comparison between intakes in April 2020 and the average intakes reported during the month of April in the previous 3 years (2017–2019; n = 1548).

FIGURE 3

PA, ST, energy intake, and body weight changes during the lockdown in the NutriNet-Santé cohort study, March–May 2020. At the top: weight change between the weight just before the lockdown and the weight in May 2020, after about 2 months of lockdown (n = 22,042); values are mean (SD) changes in participants who gained (respectively lost) weight during the lockdown. At the bottom right, daily energy intakes in April 2020 during the lockdown (n = 10,617) and comparisons with intakes observed at the same period of the year before the lockdown (April 2017–2019; n = 1548); increases and decreases were defined as changes (positive or negative, respectively) in energy intake of at least 10%; values are mean (SD) changes in participants who increased (respectively decreased) their energy intake during the lockdown. At the bottom left, modifications in PA and ST: perceived changes (n = 36,917) shown as a bar graph, with 95% CIs displayed at the extremity of the bars; quantitative assessments of changes in PA levels (in MET-min/week) and ST (time spent seated outside sleeping hours) between, before, and during the lockdown were available for subsamples of participants (n = 29,798 for PA; n = 29,788 for ST), and are shown next to each bar as median PA levels and mean ST; corresponding IQRs and SDs are detailed in Supplementary Table 3. Changes in quantitative values are also expressed as percentage changes compared to the value before the lockdown. Pregnant women (n = 335) were excluded from these analyses. Abbreviations: MET, metabolic equivalent of task; PA, physical activity; ST, sedentary time.

FIGURE 4

Usual and lockdown-specific sources of food supply, according to the urban level of the residential area during the lockdown. NutriNet-Santé cohort study (n = 37,252), March–May 2020. ¹AMAP: associations supporting small farming. ²Followed by delivery or drive-by pick-up. ³Meals, packages, subsidized grocery stores. 95% CIs are displayed at the extremity of the bars.