IntroductionCOVID-19 is a virus that has spread rapidly and brought economic and social crises all around the world. The current study aimed to investigate the impact of COVID-19 quarantine on dietary habits, physical activity, food purchasing, smoking, and sleeping patterns in the United Arab Emirates.MethodsA cross-sectional study was conducted using an online questionnaire between November 1st, 2020 and the end of January 2021. Citizens and residents of the UAE aged ≥ 18 years old were asked to complete an anonymous electronic questionnaire created via Google Forms and distributed on various platforms, such as WhatsApp, Twitter, and email. A total of 1682 subjects participated in the study.ResultsThe results included that during the COVID-19 lockdown, more participants (44.4%) reported an increase in weight. This gain seems to be linked to increased food consumption [(Adjusted Odd Ratio) AOR = 1.68, 95% (Confidence Interval) CI = 1.12, 2.54, p = 0.022], decreased physical activity (AOR = 2.25, 95% CI = 1.58, 3.21, p < 0.001), and increased smoking (AOR = 1.90, 95% CI = 1.04, 3.50, p = 0.038). The groups that were most likely to gain weight included those who consumed more cereals (AOR = 1.67, 95% CI = 1.08, 2.57, p = 0.011), had an increased desire for sweets (AOR = 2.19, 95% CI = 1.50, 3.19, p < 0.001), and an increased desire for food (hunger) (AOR = 2.19, 95% CI = 1.53, 3.14, p < 0.001). In contrast, those who exercised more were more likely to lose weight (AOR = 0.61, 95% CI = 0.44, 0.86, p < 0.001) as well as those who slept over 9 h a day (AOR = 1.90, 95% CI = 0.45, 0.88, p = 0.006).DiscussionOverall, it is essential to promote healthy habits and methods of healthy diet maintenance during stressful and unusual times when people might find it difficult to put effort into their health.