Background <p>Theoretical models suggest a dynamic interplay between self-compassion and disordered eating over time at the within-person level. Responding to periods of distress with self-kindness rather than self-judgment is assumed to reduce the risk of disordered eating, possibly by introducing self-compassion as a more effective emotion regulation strategy. Accordingly, periods of self-kindness should be associated with periods of healthier eating. However, long-term studies of the associations between moments of self-kindness and levels of disordered eating are lacking. This study aims to address this gap. We examine temporal associations between self-kindness and self-judgment and disordered eating over four years.</p> Method <p>The study is a prospective longitudinal cohort study with repeated measures. A non-clinical sample of 196 individuals with an average BMI of 32.0 (SD = 6.9), who self-identified as experiencing disordered eating were examined at four time-points over a four-year period. Participants attended an eight-week low-threshold mindfulness/self-compassion - based intervention at the start of the study.</p> Results <p>Within-person analyses showed that higher-than-usual (for that individual) self-kindness scores and lower-than-usual (for that individual) self-judgment scores predicted lower disordered eating at each measurement time-point.</p> Conclusions <p>The results accord with findings from diary studies showing that disordered eating is less likely at times when self-compassion scores are high. A potential clinical implication is that self-compassion during times of distress (including distress caused by disordered eating), might prevent disordered eating from becoming more serious and persistent.</p> <p><i>Trial registration number:</i> ClinicalTrials.gov ID: NCT05539807, 24.08.2022</p>