BackgroundMental health is more than the absence of illness and includes the ability to cope adaptively with stress. To shed light on the factors that promote mental health in people with eating disorders, this daily diary study examined whether daily and trait levels of self-compassion predict adaptive coping behaviours in women with symptoms of bulimia nervosa (BN).MethodsWomen (N = 124) who met the DSM-5 criteria for BN completed 2 weeks of nightly measures assessing their daily level of self-compassion and their daily adaptive coping behaviours, namely, their use of problem-solving strategies, seeking and receiving of instrumental social support, and seeking and receiving of emotional social support.ResultsMultilevel modelling revealed that on days when self-compassion levels were higher than their personal mean level or than the preceding day's level, participants reported greater use of problem-solving strategies, greater seeking and receiving of instrumental social support, and greater receiving of emotional social support. Daily levels of self-compassion, but not increased self-compassion from the preceding day, were associated with emotional support sought. Further, higher trait self-compassion, as measured by participants' mean level of self-compassion over the 2 weeks, was associated with increased seeking and receiving of instrumental and emotional social support but not with problem-solving strategies. All models controlled for participants' daily and mean eating pathology over the 2 weeks, highlighting the unique contribution of self-compassion to adaptive coping behaviours.ConclusionsResults suggest that self-compassion may help individuals with symptoms of BN cope with challenges in their daily life more adaptively, an integral component of positive mental health. The present study is among the first to suggest that the benefits of self-compassion for individuals with eating disorder symptoms may lie not only in facilitating reduced eating pathology, as evidenced by prior research, but also in promoting positive mental health. More broadly, findings underscore the potential value of interventions designed to build self-compassion in individuals with eating disorder symptoms. Plain English summaryThere is a call in the eating disorder field to identify factors that not only reduce eating disorder symptoms, but also promote positive mental health. Yet, the factors that interventions might target to accomplish both of these goals remain relatively unknown. Self-compassion, which is a way of responding to personal distress with care and understanding, has been linked to fewer eating disorder symptoms. In non-eating disorder populations, self-compassion also promotes adaptive coping behaviours, including problem-solving and calling on others for support, key aspects of mental health. To test whether these benefits of self-compassion extend to people with eating disorders, we had women with symptoms of bulimia nervosa complete questionnaires about their daily level of self-compassion and their daily adaptive coping behaviours every night for 2 weeks. We found that on days when women were more self-compassionate than usual or more self-compassionate than the day before, they reported using more adaptive coping strategies. Further, individuals who were generally more self-compassionate than others over the 2 weeks reported receiving more social support from others. Our results are the first to suggest that, by treating themselves with compassion, individuals with eating disorder symptoms may cope more effectively with challenges in daily life.