Eating Disorders (ED) represent a group of psychiatric disorders characterized by disturbance of eating behaviors, which results in altered food consumption and impairments in physical health and psychosocial functioning [1].

The clinical burden of ED is frequently worsened by a series of mental or physical comorbid conditions, such as Mood Disorders, Personality Disorders, Autism Spectrum Disorder, and cardiovascular problems [2,3,4,5]. According to recent studies and clinical guidelines addressing ED in the developmental age, ED treatments may include nutritional interventions, family-based treatments, cognitive behavioral therapy, adolescent-focused psychotherapy, and psychotropic drugs [6,7,8].

Current research suggests a role that multiple and different factors play a role in the pathogenesis of ED, including genetic, neurodevelopmental, environmental and cultural factors [9]. Specifically, multifactorial hypotheses on the pathogenesis of ED distinguish among predisposing (genetic, biological, individual and family psychological, social), precipitating (abuse, illness, divorce) and maintenance (hormonal and neurotransmission imbalances) factors [10, 11]. In recent years, the role of Internet use in the pathogenesis of ED has been repeatedly studied [12, 13].

Two new terms have become part of the common language of the Web: pro-Ana and pro-Mia. Pro-Ana, which stands for pro-Anorexia, means “promoting Anorexia Nervosa” (AN). This may refer to websites, blogs, or communities that enhance AN and provide users with advice on how to achieve AN and its commonly-referred features. Similarly, pro-Mia, which stands for pro-Bulimia, means “promoting Bulimia Nervosa” (BN) [13, 14]. Pro-Ana and pro-Mia (pro-ED) communities promote ED as a lifestyle choice rather than as disorders that ought to be treated [15,16,17,18]. These trends – in fact “movements” with followers and devotees – have massively evolved since their first appearance in and as websites in the 1990s [19] on account of the radical change brought about by “highly interactive” social media (SM) communication dynamics. Sites have changed from providing a static and heavily moderated context to being a more visual and considerable [1] less hierarchical environment, which is more easily accessible and open due to the high number of public accounts and thus, more difficult to moderate due to the large volume of cross-tagged images and related hashtags [20].

The focus of this investigation is the SM TikTok, which was launched in 2016 and is one of the fastest-growing mobile applications with an estimated 800 million active users, the majority of whom are children and teenagers [21, 22]. This application is based on the sharing of brief videos associated with captions and several hashtags. Its remarkable peculiarity is that it is a completely algorithm-driven and content-oriented platform; so, each user will automatically receive personalized content on their main feed based on user interaction (i.e., like, dislike, but also video completion rate), video information (e.g., hashtags, captions or sounds) and account settings. Moreover, unlike other SMs, TikTok users receive personalized content from anyone on the platform rather than just from the accounts that they follow [23, 24].

Given the platform’s architecture and the variety of cross-linked hashtags, users who may be watching videos on weight loss or calories checks may soon receive a greater variety of eating-related information in their main feed, from “thinspiration” contents, which cover more mainstream dieting practices, to clearly “pro-Ana” ones [25].

A similar dynamic has been descripted for the phenomenon known as “challenges” [26]. Challenges bring many TikTok users to make videos of their attempts to reproduce the same specific trending tasks. Some of these challenges revolve around ED-related topics. Examples include the “#A4waistchallenge”, where people demonstrate that the size of their waistline is less than the width of an A4 sheet of paper placed vertically, or the “#headphonechallenge”, based on measuring waists using headphone wires [27, 28]. In a socio-cultural context already characterized by an increasingly blurred line between pro-ED contents and mainstream espousals of thinness [29, 30], TikTok challenges facilitate and increase the exposure of a growing number of users to all kinds of ED-related problematic content, which adds to the impressive adaptability of the app – through, for instance, the simple creation of new hashtags via the misspelling of previously banned ones – to evade strict oversight [31,32,33].

At the same time, due to the more open and public configuration of this application and the changed approach of new generations of users, who tend to share more openly and are more committed to raising awareness about and normalizing mental health issues [34], TikTok has simultaneously proved to be a thriving opportunity to create an easily accessible digital space for the positive content of such hashtag communities as “pro-EDrecovery”, “raisingEdawareness” and others [35, 36]. Clustering under the same hashtag, the users of these communities share their experiences and provide advice and support to one another by sharing their recovery processes, struggles and personal stories. They assert themselves and others by challenging the emphasis society and culture place upon being thin. They do so, for example, by countering those trends which praise thinness, by using the same hashtags to spread, instead, body-positivity messages (see #dontjudgechallenge #bodyodychallenge) [37]. It is thus possible to categorize materials and hashtags relating to diet as a general concept (food, its preparation and relationship with the body), pro-Ana (promoting eating disorder-related behaviors and mindsets), and pro-ED recovery contents (focusing on spreading awareness about ED and encouraging people with to continue their treatment path).

In light of all the above, a pressing need exists to understand the complex nature and conflicting characteristics of SM usage, and to fully explore how a relationship with SM, whether actively sought or accepted through passive exposure, can influence a sensitive population group such as our young and adolescent patients with regard to body image concerns and eating disturbances. This paper describes the use of TikTok in a group of children and adolescents referring to a third-level Italian center for ED during the SARS-CoV-2 (COVID-19) pandemic, with the goal of identifying general patterns in the use of TikTok by young people with ED. This study is the first survey conducted in Italy on the use of TikTok among patients with ED in developmental age. Our working hypothesis is that the analysis of the personal views of individuals with ED on TikTok may provide new insights into the potential risks and benefits of SM use in mental health.