Eating disorders are psychopathologies with serious repercussions on the somatic, psychological and social level. Currently available treatments are unfortunately for now not fully efficient, therefore researchers have recommended to develop prevention initiatives. Until now, no study has been carried out in Switzerland to evaluate the efficacy of an intervention for the prevention of eating disorders.

The goal of the present study is to evaluate two eating disorders prevention intervention that have been largely validated in the US, called the Body Project (BP) and the Healthy Weight Program (HW). Both interventions target body dissatisfaction, which is a well-identified risk factor of eating disorders. They will be compared to a one-month waiting list. Because of the pandemic situation due to the Severe Acute Respiratory Syndrome coronavirus (COVID-19), both interventions will be delivered virtually via a collaborative platform. The sessions will be recorded to carry out a quality control.

To compare the BP and HW interventions to a waiting list, a three-arm randomized controlled study will be carried out, including female students from French-speaking Switzerland. Recruitment will include 90 participants. Participants will be randomly assigned to one of the three arms of the study. They will be evaluated before (T0) and after (T1) the interventions or the waiting list. Following the interventions, the participants will have one month of follow-up before a final evaluation (T2). Participants on the waiting list will receive the BP following the one-month waiting period and will then be evaluated (T2).

After having signed the consent form, the participant will be randomized to one of the three study arms, with a 1: 1: 1 allocation ratio. Interventions will be given in groups of six participants. Randomization will be blocked to ensure groups of equal size, and that groups of six participants for each arm are regularly formed. The blocks will be of variable size (3, 6, 9) to protect the concealment.

The hypotheses are as follows:

1. The two interventions BP and HW will have an effect on body dissatisfaction (primary outcome) as well as on the thin-ideal internalization, dietary restraint, negative affect, and eating disorders psychopathology (secondary outcomes), compared to the waiting list;
2. There will be no differences between the BP and the HW on the primary and secondary outcomes;
3. The effects observed thanks to the interventions will be maintained after one month of follow-up.

Inclusion Criteria:

• Female student;
• Aged between 18 and 25 years old;
• BMI between 18.5 and 30 kg/m2;
• French-speaking (or understand French sufficiently to participate in the intervention) and having lived in Switzerland for at least six months;
• Suffering from body dissatisfaction and obtain a score of at least 26 on the Body Shape Questionnaire 8-item (BSQ-8C) which represents a moderate concern with her body image;
• Accepting the use of a collaborative platform to participate in the intervention group, which implies that her name may be revealed, and accept that the sessions be recorded.

Exclusion Criteria:

• Eating disorder according to the Diagnostic and Statistical Manuel of Mental Disorders 5th edition (DSM-5) diagnostic criteria (past or current);
• Diagnosis of mood disorder or anxiety disorder;
• Pregnancy.

At the end of the study, the data will be stored in a repository which guarantees archiving and data sharing in accordance with Findability, Accessibility, Interoperability, and Reuse of digital assets (FAIR) principles.

The participants and the collaborators performing the interventions will not be blinded to the conditions. In order to minimize bias, the main statistical analyses aimed at evaluating the hypotheses will be performed by a statistician blinded to the participants' allocation.