A novel coronavirus, known as coronavirus disease 2019 (COVID-19), was identified in late 2019 and rapidly spread worldwide, becoming the most significant global public health threat of the century (1). To prevent the spread of COVID-19, the Korean government implemented a social distancing policy on March 21, 2020 (2). It included limits on the number of people in gatherings, permitted crowd sizes at sports facilities, requirements for electronic log systems, restrictions on business hours, and bans on eating food in indoor public spaces—all of which can affect individual’s social activities (2).

Obesity is an important risk factor for various chronic diseases, including type 2 diabetes, cardiovascular diseases, musculoskeletal diseases, and several types of cancer (3). According to the 2023 Obesity Fact Sheet of Korea, the prevalence of obesity increased from 30.2% in 2012 to 38.4% in 2021, and that of abdominal obesity increased from 21.4 to 31.0% in the same period of time (4). These consistent upward trend in obesity prevalence has been observed across both sexes and all age groups in Korea (4). Previous studies have reported that the prevalence of obesity, morbid obesity, and mean BMI increased during the COVID-19 pandemic compared to the pre-pandemic period (5–7).

The implementation of social distancing policies during the COVID-19 pandemic may have influenced changes in health behaviors and restrictions on daily life for the general population. Additionally, these unhealthy lifestyle factors may be associated with social distancing policies, such as a lack of physical activity (8). Therefore, our study aimed to investigate the association between restrictions on daily life during COVID-19 pandemic and obesity levels in Korean population using the Korea Community Health Survey (KCHS).

In this study, self-reported restrictions on daily life during COVID-19 were more frequently reported by obese men than by those with normal weight. Additionally, both decreased physical activity and increased fast food consumption were more common among the obese group. In women, daily life restrictions did not significantly differ between BMI groups. However, similar to men, decreased physical activity and increased fast-food consumption were more frequent in the obese group. These two factors also showed a significant trend across increasing obesity levels.

This study showed differences in the presence of daily life restrictions, decreased physical activity, or increased fast food consumption based on obesity levels. These unhealthy lifestyle factors were observed during the study period when social distancing policies were implemented in Korea and their prevalence varies according to the degree of obesity. Previous studies have reported that social distancing policies and restrictions on daily activities contribute to increased obesity and weight gain (15, 16). A large study conducted among older adults in England reported that a short 2-month lockdown in 2020 during COVID-19 pandemic led to weight gain, which was associated with decreased physical activity, increased sedentary behavior, increased food intake, and longer sleep duration (15). However, it focused on the health behaviors changes related with weight gain during lockdown and did not compare weight changes between the normal weight and obese group. A study from Brazil similarly found that social distancing policies were related with weight gain (16). Specifically, while 46.6% of individuals with a normal BMI reported weight gain, this proportion rose to over 87% among those classified as overweight or obese. Also, the overweight and obese groups reported less total weekly physical activity and more frequent binge eating compared to the normal-weight group (16). However, the study had a small sample size based on an online survey, which may limit the generalizability of the findings.

We found that individuals with obesity were more likely than those with normal weight to experience limitations in daily life, reduced physical activity, and increased consumption of fast food during the implementation of social distancing policies. Moreover, the finding of this study is that these tendencies became more pronounced with increasing obesity severity. Supporting our findings, a recent qualitative study has shown that obese individuals find more challenging to make healthier choices when faced with the option between a healthier choice and an easier choice (17). Additionally, although the study focused on children, a recent study about Austrian pediatric population reported that approximately half of overweight children became obese during the pandemic (18).

In our study, the presence of self-reported restrictions on daily life increased among obese men, but did not differ by weight group among women. Similar with our study, a previous study about Korean general population showed that obesity increased from 2019 to 2020 among men but not women, which was mainly associated with decreased physical activity (19). In Korea, since men generally tend to have higher levels of physical activity compared to women, it is possible that men’s physical activity may have been more affected by COVID-19 pandemic (20). Additionally, women usually have more social pressure to maintain their weight in Korea (21). A previous study in Korea reported that women engaged in more weight control efforts, which were associated with their subjective perception of their body rather than their actual BMI (22). Thus, women may have paid more attention to weight management than men during the COVID-19 pandemic. From a biological perspective, cortisol levels in men tend to be higher than in women in response to stress (23). Perceived stress may influence HPA axis function, thereby affecting the risk of obesity and metabolic syndrome. Moreover, in men, serum free cortisol levels and cortisol production rates were associated with increased visceral fat and insulin resistance (24).

Most previous studies primarily focused on data from 2020 (15, 16, 25), covering only a limited period even though the COVID-19 pandemic continued until 2021. In contrast, our study analyzed data collected during August to October of both 2020 and 2021 including the period following the start of the vaccination rollout—adding significance to our findings. In particular, Korea’s social distancing policy was implemented through a graded system, where restriction levels were adjusted according to the number of confirmed COVID-19 cases (26). Furthermore, we used data from the Korea Community Health Survey, a nationwide survey, enhancing the generalizability of our results. As noted in previous research (27), social distancing policies may contribute to further obesity in obese populations already affected by obesity. It suggested that consideration for individuals with obesity may have been necessary in the implementation of policies.

This study has several limitations. First of all, as this was a cross-sectional study, it was difficult to establish causal relationships. Although we presented that participants with obesity reported decreased physical activity and increased fast-food intake, it is also possible that those who experienced decreased physical activity and increased fast-food consumption became obese during the COVID-19 period. Second, as obesity and influencing factors were assessed based on a self-reported questionnaire, some discrepancies compared to actual measured values may exist. Participants may have underreported their weight, potentially leading to an underestimation of the obesity prevalence. However, our results are based on relative differences in self-reported decreases in physical activity across BMI categories, rather than actual measurement of BMI. While one study has shown that self-reported BMI did not significantly differ from actual measurements (28), another study showed a tendency toward underreporting BMI, especially among high BMI individuals (29). Self-reported physical activity and dietary habits may have recall bias and social desirability bias (30, 31). A previous study has also shown that women tended to underreport their energy and fat intake (30). Regarding physical activity, self-reported activity levels may differ from objectively measured levels (31). Therefore, the findings of this study may have been underestimated and the overall direction of the results is expected to remain consistent. In addition, this study asked about perceived increases or decreases in activity, and thus the results can be interpreted as reflecting individuals’ subjective evaluations of changes in their behavior. Furthermore, previous research has shown acceptable test–retest reliability for health behavior questionnaires in the KCHS (32), indicating they may be used to assess changes in health behaviors. Third, while physical activity can be influenced by seasonal variation, both the 2020 and 2021 Community Health Surveys were conducted during the same period, from August to October. As such, the likelihood that seasonal effects significantly impacted the reporting of physical activity levels is considered low. Finally, we used quartile-based categorization of daily life restriction scores considering their distribution. This is a commonly used method for categorizing variable but the lack of validation is a limitation of this study. Nevertheless, this study is representative of obese groups by sex and has yielded significant findings, evaluating that obese individuals reported the greater restrictions on daily life.

This study found that individuals with higher obesity levels were more likely to report negative changes in their health behaviors such as decreased physical activity and increased fast food consumption. These findings highlight the need for targeted strategies to support people with obesity during a public health crisis. A recent study showed the clinical effectiveness of telemedicine for the control of chronic diseases including physical conditions (33). A recent study reported that app-based programs for individuals with obesity, including self-management, self-monitoring, and audio- or video-based education, can lead to weight loss (34). Accordingly, various home-based exercise programs, mobile applications for dietary and activity monitoring, and strengthened health education targeted toward high-risk groups might be beneficial for their health. In situations like the COVID-19 pandemic, when face-to-face access is limited, such digital and remote interventions can play a crucial role in supporting the health of vulnerable populations. Accordingly, it may be beneficial for health policies to consider strategies for the management of obesity in these high-risk groups.