The main aim of this project was to explore the efficacy of Acceptance and Commitment Therapy (ACT)‐based educational course in different formats (i.e., pure and guided self‐help with different durations, and guided self‐help with and without access to a discussion forum) for body shape dissatisfaction. Two randomized controlled studies (RCT) were carried out. In the first RCT, the participants were randomized to a 12‐ or 16‐week guided self‐help, a 16‐week pure self‐help, or a waitlist control condition. In the second RCT, the efficacy of 12‐week guided self‐help with or without access to a discussion forum was investigated. ACT‐based self‐help resulted in promising improvements in body shape dissatisfaction, and modest effects on general health indicators (i.e., symptom of depression, self‐esteem, satisfaction with life, and quality of life). The findings also showed no additional effects of support, access to the online discussion forum, and longer duration of self‐help, suggesting the 12‐week self‐help with or without support is a viable option for reducing body shape dissatisfaction.