In 2022, the smartphone ownership rate of elementary school students nationwide was 93.9%, up from 24.1% in 2012 [1]. The smartphone is an intelligent terminal that adds several computer support functions to the mobile phone and is characterized by the user’s ability to install an application desired by the user [2]. Because smartphones can be used immediately without time and space constraints, smartphones are preferred over the Internet [3]. Smartphone addiction causes maladjustment in school, home, and daily life. The maladjustment occurs because they are too immersed in the use of smartphones and cannot control themselves [4]. Overdependence has replaced addiction, a word that can give negative perceptions [5].

According to National Information Society Agency (NIA), overdependence on smartphones is a state in which the prominence of smartphones increases, and the self-control power decreases due to excessive use of smartphones, resulting in serious consequences. Among the three factors that cause dependence on smartphones, the first self-control failure is the user’s poor ability to self-regulate smartphone use compared to their personal goals. Second, salience is when smartphone use becomes the most critical activity in an individual's life above anything else. Third, serious consequences are defined by continued smartphone use despite various negative consequences to the user because of smartphone use [6].

According to a survey conducted by the Ministry of Gender Equality and Family in 2021, 129,543, or 10.4% of 1.25 million adolescents, were overdependent on smartphones. The overdependence on the Internet and smartphones also increased in 2020 for both boys and girls in the fourth grade of elementary school [7]. In a 2022 survey by NIA, middle school students were the most at-risk group for smartphone overdependence: kindergarten (24.7%), elementary school students (33.6%), middle school students (44.5%), high school students (40.0%), and college students (34.1%) [6]. The excessive use and dependence of these smart devices has become a new social problem in the health and psychology of infants and adolescents who find it difficult to self-regulate [8].

In 2014, the access to dietary information through smartphones in high school students in Incheon increased compared to the past when using computers [9]. In 2018, middle school students in Seoul mainly used social network service and smartphone as mass media to obtain dietary nutrition information [10]. According to previous studies on the influence of the Internet and various media on eating habits of 4th- to 6th-grade elementary school students, the number of snacks consumed, preference for processed food snacks, and frequency of consumption were high in groups with more than two hours of television viewing in Gyeongsangnam-do in 2013 [11]. In 2014, elementary school students in Ansan showed a negative correlation between weekend smartphone usage time and good eating habits scores. As smartphone usage time increased, they tended to consume excessive snacks [12]. In 2016, the group who used smartphones for more than two hours in Cheongju had a higher frequency of eating ice cream, snacks, and soda compared to the group who used smartphones for less than two hours; furthermore, those who used a smartphone for less than two hours had generally desirable eating behavior [13].

In 2011, among middle school students in Gyeonggi-do, the Internet-using group reported that eating speed increased and snacks increased, and the higher the degree of Internet use, the more negatively affected dietary attitudes [14]. In 2014, among high school students in Incheon, male students had increasingly poor eating habits, reflected by lower scores on eating behavior, as the degree of addiction to smartphones was higher [9]. In 2018, high school students in the Gyeonggi area and Seoul had negative effects on their eating habits if they watched food content [15]. In 2022, young people in their 20s and 30s across the country primarily viewed social media on their smartphones, and the average daily social media usage time was longer in groups with high levels of food content use. When the level of food content use was high, some poor eating habits were higher [16]. These studies demonstrate that excessive use of the Internet or smartphones negatively affects snack and eating habits.

According to the Ministry of Education’s elementary school student health test conducted in 2022, the rate of fast-food consumption more than once a week increased from 68.6% in 2019 to 77.8%, and the rate of beverage consumption more than once a week also increased from 80.9% in 2019 to 85.8%, increasing negative eating habits [17], indicating the need for improvement in dietary behavior [18]. The prevalence of obesity among elementary school students has also increased [17]. In a 2020 study of elementary school students in Busan, the overweight and obese groups had a higher intake of snacks with higher sugar content [19]. Therefore, the eating habits of elementary school students in Korea are deteriorating, and the prevalence of obesity is also increasing.

An increase in the body mass index (BMI) in childhood can be an important predictor of obesity in adolescence and adulthood [20], hence it is necessary to form eating habits properly at a young age [21]. In middle and high school students, the higher the score of obesity-related eating attitude and the shorter the eating time, the higher the BMI [22]. The ratio of overweight and obesity combined (OOC) middle school students in Gangwon-do was 42.1% (male students 43.1%, female students 40.9%) [23], which was higher than the national rate of 32.8% (male students 37.3%, female students 27.6%), and the proportion of OOC female middle school students in Gangwon-do was especially high. However, the proportion of OOC elementary school students is 27.0% in Gangwon-do, which is lower than the national rate of 29.8% [17,23], so elementary school students in Gangwon-do must form proper eating habits in the process of growing into middle school students.

Therefore, we investigated whether the use of smartphones is related to eating behavior for 4th- to 6th-graders of elementary schools in Gangneung via survey.

This study investigated whether the use of smartphones is related to eating behavior in the 4th- to 6th-grade elementary students in Gangneung. The 86.4% smartphone ownership rate of the study subjects was lower than the 89.3% ownership rate for people aged 3–19 living in small and medium-sized cities in 2022 [6] and was also lower than the 93.9% of elementary school students nationwide in 2022 [1]. The smartphone ownership rates were 84.6% of the boys and 88.9% of the girls, and there was no significant difference according to gender, and the higher the grade, the higher the smartphone ownership rate. The proportion of students in the Org was 42.1% (24 students), which is higher than the 33.6% of elementary school students nationwide in 2022 [6]. In previous studies of elementary school students, the proportion of the risk group of overdependence continued to increase to 10.1% in Ansan in 2014 [12], 2.7% in Cheongju in 2016 [13], and 18.2% in Siheung and Ansan in 2017 [26]. Despite the lower smartphone ownership rates for elementary school students in Gangenung, the proportion of the Org was higher.

In terms of smartphone dependence, 45.5% of boys and 37.5% of girls were at risk of overdependence, and there was no significant difference according to gender [12]. In the 2018 survey, male students in elementary school were more dependent on smartphones than female students [27]. In the 2022 survey, the rate of dependence on smartphones for kids between the ages of 10 and 19 was higher in girls than boys [6]. As such, previous studies showed differences in the rate of dependence on smartphones according to gender, but this study does not demonstrate a significant difference due to the small number of study subjects. Looking at the dependence on smartphones according to grade, the difference was not significant in the number of students in the Org.

Compared to the control failure (2.88 points), salience (2.75 points), and serious consequences (2.75 points) of the 2022 survey’s the risk group of overdependence on elementary school students [6], the control failure factor (3.03 points) of the Org was higher and the salience factor (2.67 points) and serious consequences (2.23 points) were lower. So the Org in Gangneung are considered to have a great difficulty in the self-control failure. The study subjects’ weekend smartphone use time was about 5.53 hours, the Org was 7.54 hours, and the Gug was 4.06 hours, which was more than the 3.86 hours for 4th-grade elementary school students nationwide reported in 2018 [27]. The use time of the Org was significantly higher than that of the Gug, and the Gug used 1–4 hours the most at 69.7%, while the Org used more than 5–10 hours the most at 45.8%.

The average healthy eating behavior of the study subjects was 2.35 points, and the average unhealthy eating behavior was 1.89 points. The average healthy eating behavior of the Org (2.26 points) was lower than the Gug (2.42 points), but the difference was not significant. The average unhealthy eating behavior (2.02 points) of the Org was higher than that (1.80 points) of the Gug, but the difference was not significant.

According to previous studies on the eating habits of elementary school students, a 2006 study [28] showed that the longer the computer use time, the lower the eating habits score. In the 2014 study [12], the smartphone addiction group had lower scores on good eating habits than the general group and higher scores on bad eating habits. In the 2017 study [26], the food behavior score of the risk group of overdependence was lower than that of the general group. As such, in previous studies, the eating habits of the risk group of overdependence were not more desirable than those of the general group. The Org in this study tended to have fewer healthy eating behaviors and more unhealthy eating behaviors than the Gug, but the reason why there was no significant difference is considered to be due to the small number of study subjects. In this study, eating sweet food of the Org (2.33 points) was higher than that of the Gug (2.00 points). In the 2016 study of 5th- to 6th-grade elementary school students, the group who used the smartphone for more than 2 hours had a higher frequency of eating ice cream, snacks, and soda than the group who used it for less than 2 hours [13]. In a 2020 study of 4th- to 6th-grade elementary school students in Busan, the overweight and obese groups had a higher intake of snacks with higher sugar content than the normal weight group [19], so it is considered necessary to control the intake of snacks with high sugar content in the risk group of overdependence.

The number of days of snack consumed per week of the study subjects was about 5.35 days, the Org was 5.75 days, and the Gug was 5.06 days, and there was no significant difference, as they all were eating snacks more than five days of the week. In 2021, the percentage of elementary school students in Gyeonggi-do who ate snacks more than twice a day was the highest at 37.6% [25]. The number of days of late-night snacks consumed per week of the study subjects was 2.47 days, the Org was 2.92 days, and the Gug consumed late-night snacks 2.15 days, and there was no significant difference. In the 2021 Gyeonggi-do study of 4th- to 6th-grade elementary school students, 55.9% of them rarely eat late-night snacks during the week and 28.3% of them eat once or twice a week [25], so it is considered that elementary school students in Gangneung eat late-night snacks more often.

As a result of analyzing the subject’s eating behavior, consumption of fast food had a positive correlation with eating fatty foods, sweet foods, and heavily seasoned foods, indicating that frequently eating fast food is closely related to unhealthy eating behavior. The number of days of snack consumed per week was not significantly related to the eating behavior variable, but in Kim & Kim’s study [12], the number of snacks consumed was positively correlated with the bad eating habits score, resulting in different results. The number of days of late-night snacks consumed per week showed a significant positive correlation with all variables of unhealthy eating behavior, so it is considered that the number of days of late-night snacks consumed per week should be treated as an important factor when investigating eating behavior.

Smartphone dependence showed a negative correlation with the average healthy eating behaviors, eating three regular meals, and eating a variety of foods, as well as showed a positive correlation with the average unhealthy eating behavior, eating sweet food, and eating heavily seasoned food.

Weekend smartphone usage time showed a significant negative correlation with eating three regular meals, and a negative correlation with other healthy eating behavior questions was found but was not significant. In Kim & Kim’s study [12], weekend smartphone usage time and good eating habits scores showed a negative correlation. And the group using smartphones for less than 2 hours had more desirable eating behavior than the group who used phones for more than 2 hours [13]. Weekend smartphone usage time was positively correlated with the average unhealthy eating behavior, eating fatty food, heavily seasoned food, and eating healthy. However, in Kim & Kim’s study [12], weekend smartphone usage time was not significantly correlated with bad eating habits.

Weekend smartphone usage time showed a positive correlation with smartphone dependence and the number of days of late-night snacks consumed per week, but in both this study and Kim & Kim’s study [12], weekend smartphone usage time was not significantly correlated with the number of days of snack consumption. This study recruited survey subjects through the convenience sampling method, and the number of respondents is small, so it is difficult to generalize.

As a result of investigating the relationship between smartphone usage in elementary school students in Gangneung region, the percentage of smartphone ownership was lower than the nationwide statistics, but the rate of smartphone overdependence was higher. Smartphone dependence had a negative correlation with healthy eating behavior and a positive correlation with unhealthy eating behavior.