A study done on related risk factors for weight gain during the COVID-19 quarantine reports five main predictors of weight gain: inadequate sleep, snacking after dinner, lack of dietary restraint, stress eating, and lack of physical activity¹.

References

1. Zachary, Z., Brianna, F., Brianna, L., Garrett, P., Jade, W., Alyssa, D., & Mikayla, K. (2020). Self-quarantine and weight gain related risk factors during the COVID-19 pandemic. Obesity Research & Clinical Practice, 14(3), 210-216. doi:10.1016/j.orcp.2020.05.004
2. Mattioli, A. V., Puviani, M. B., Nasi, M., & Farinetti, A. (2020). COVID-19 pandemic: The effects of quarantine on cardiovascular risk. European Journal of Clinical Nutrition, 74(6), 852-855. doi:10.1038/s41430-020-0646-z