As Internet technology continues to develop, social media such as Weibo, WeChat, QQ, Tik Tok and so on have become an indispensable part of life. According to the latest released official report from the China Internet Network Information Center (CINIC), there are almost 0.751 billion netizens in China, accounting for 1/5 of the netizens globally . Of these, most social media users constitute young adults at the age of 18–24 years. The top three most popular used social medias were Wechat (utilization ratio: 85.5%), QQ (utilization ratio: 67.8%), and Sina Weibo (utilization ratio: 37.1%) . As early contact and wide users of social media, college students' dependent behavior of social media is particularly prominent . Its widespread use has increased the ease of interpersonal communication between individuals, and socialization processes; yet, problematic use of social media has become prevalent among a large proportion of users and led to significant behavioral and psychological problems . Problematic social media use has repercussions on users’ social, psychological, and personal lives . When individuals are so engaged in social media that they feel distressed when they are unable to use it, such misuse is widely referred to as social media dependence (SMD) [5, 6].
Online social media behaviors (e.g., viewing and commenting) have been significantly correlated with a drive for thinness among undergraduate students . Eating disorders (ED) risk, especially among young adults, have become a worldwide concern . Stanghellini proposed  that persons with ED experience their own body first and foremost as an object being looked at by another, rather than from a first-person perspective. They developed and validated a new self-reported questionnaire named IDEA (IDentity and eating disorders), which represents a multidimensional, brief, versatile, easy-to-perform instrument . IDEA has been reported to be specifically associated with the core features of ED psychopathology and to show good internal consistency, valid incremental validity as compared with other scales devoted to the measure of eating disorders psychopathology (e.g. eating disorders Examination Questionnaire and eating disorders Inventory, EDI-1) [9,10,11].
The relation between social media dependence and eating disorders risk among college students
Social media dependence has been associated with an increased risk of eating disorders especially among young adults who are easier to access internet and spend most of their time for social networking . Associations between social media use and ED pathology was found [7, 13,14,15,16]. Time spent on Facebook appears to be associated with body image dissatisfaction and eating disorders pathology, with the relationship between Facebook and ED stronger compared to viewing ‘Barbie’ type models on television and magazines . Social media can create a climate of social comparison and preoccupation with thinness and beauty, which can pose risks for emotional problems, such as depression and social anxiety. With the widespread use of social media, this behavior triggers the extreme pursuit of thinness and beauty among youths. In face of beautiful images on social media, young adults are more likely to resent their physical image . Those who are more dissatisfied with their appearance are more likely to suffer from depression, eating disorders risks . Previous studies have found, young adults who use more Facebook are more dissatisfied with their appearance . Besides, Facebook use may contribute to disordered eating by maintaining risk (i.e. weight/shape concerns and state anxiety) for eating pathology compared to an alternate internet activity . In many ways, social media dependence and eating disorders tendency are closely intertwined [14, 20].
The use of social media is most common among college students than other adults . Young adults primarily use social media for communication, entertainment, and professional development, making it indispensable for college students . Life habits are usually formed during young adulthood . College students are easy to form habits in life and behavior, and more easily influenced by their peers, with strong plasticity . More time spent on Facebook relates to more frequent body and weight comparisons, more attention to others’ physical appearances, and more negative feelings about their own bodies . College students are, thus, at risk of disordered eating attitudes owing to the elevated mental and physical demands of higher education .
Impulsiveness as a moderator
Does the relation between social media dependence and eating disorders risk have something to do with impulsivity? Impulsiveness is defined as action without good planning and with little consideration of the consequences. Self-control can be defined as the choice of a larger, more delayed reinforcer over a smaller, less delayed reinforcer, and impulsiveness as the opposite . Acting impulsively is an action based on the impulse to express a desire . Acting impulsively also means acting without thinking about the action first, a behavior that wants to get immediate feedback from the environment, or impatient behavior to delay its desire. The cause of a person behaving impulsively is a case related to attention and active behavior, so there is no definite cause. According to experts, there are many factors that encourage a person to behave impulsively, such as the nature that tends to hyperactive, temperamental, environment influences. The message that ‘thinness is beauty’ circulated in social media environments, attracts expanding research attention and growing interests. Impulsivity was regarded as a multi-dimensional construct. Historically, research on impulsivity in eating disorders has been primarily focused on individuals with bulimic-spectrum disorders (i.e., those involving binge eating and/or purging behaviors, including bulimia nervosa, binge eating disorders, purgative anorexia nervosa and binge eating/purging subtype of anorexia nervosa) .
Although social media use, such as Facebook, may lead to eating disorders risk , it is possible that not all people are equally influenced by its effects. Consequently, it is important to examine variables that may moderate the relationship between social media dependence and negative outcomes. It’s worth noting that restrictive anorexia nervosa patients (AN-R) reported less impulsiveness scores than controls [27, 28]. In general, maladaptive aspects of perfectionism (e.g., perseverance behaviours), the opposite of several traits of impulsiveness (e.g., lack of planning and perseverance), is well-established as the risk factors for the relationship between social media environment and eating disorders [29, 30]. They found support for the moderation hypothesis, with girls high on both perfectionism and body dissatisfaction exhibiting the highest levels of eating disorders symptoms. Thus, impulsiveness may be an important factor that impacts the relation between social media dependence and eating disorders risk . Therefore, the relationship between the social media environment and eating disorders was not only related to the level of social media dependence but to impulsivity and self-control. The higher the degree of social media dependence and the planned self-control, the more likely individuals are to be influenced by the social media thin-ideal content and adhere to unhealthy eating behaviors and body image dissatisfaction. On the contrary, for the individuals with high impulse-type and poor self-control, although they are influenced by social media thin-ideal content, it is difficult for them to stick to their idea and actions .
The current study
In the present study, we tested moderator models of the relation between social media dependence and eating disorders risk. To summarize, the current study examined the relationship between social media dependence and eating disorders risk. Firstly, we expected that social media dependence would be a risk factor for eating disorders tendency, with high social media dependence predicting high eating disorders tendency. Secondly, we further explored whether this association would be moderated by impulsiveness, and expected that the direct effect would be stronger for individuals with low impulsiveness than for those with high impulsiveness. Given that low self-control may buffer people from the negative impact of social media environment, we expect that high impulse-type might instead serve as a protective factor for the effect of high level of social media dependence on identity and eating disorders risk .