The COVID-19 pandemic impacted dietary habits and physical activity patterns, with some long-term consequences. This study evaluated the effects of the pandemic on adults' dietary habits and physical activity in Jazan and compared them to pre-pandemic. An analytical cross-sectional survey was conducted among conveniently selected 559 individuals in Jazan, Saudi Arabia, in February 2022 using a validated online questionnaire. Data was collected to assess changes in eating habits, food intake, and weight before and 21 months after lifting of COVID-19 curfew restrictions in the region. Chi-squareand McNemar's tests were used for analysis. The proportion of individuals consuming homemade meals decreased from 50.6% (n=283) before the pandemic to 46.5% (n=260) during the pandemic, while the proportion of participants consuming less than three meals per day increased from 42.2% (n=236) to 45.4% (n=254), and breakfast consumption decreased significantly from 58.1% (n=325) to 53.5% (n=299) (p = 0.033). There was an increase in the consumption of fast food from 10.7% (n=60) to 12.0% (n=67) and dining at restaurants from 18.4% (n=103) to 19.3% (n=108); however, these increases were not statistically significantcompared to pre-pandemic rates. During the pre-COVID-19 period, 46.9% (n=262) reported engaging in physical activity one to three times a week, whereas this frequency decreased to 41.3% (n=231) during the pandemic (p = 0.017). In contrast, a significant increase was observed in the duration of computer usage as prior to the pandemic, 20.2% (n=113) reported spending more than five hours per day on the computer, while this proportion increased to 31.8% (n=178) during the pandemic (p < 0.001). Furthermore, a considerable proportion of both males and females, constituting over one-third (n=189) of the total sample, reported an increase in body weight. The findings suggest that the adult population in the Jazan region of Saudi Arabia experienced significant lifestyle changes during the COVID-19 pandemic, including altered dietary patterns and a significant decline in physical activity. To mitigate potential adverse effects on future well-being, it is crucial to implement enduring initiatives promoting healthy lifestyles.