Purpose: The current study examined the relevance of familial environment (negative maternal messages) to the phenomenon of maladaptive (obligatory) exercise, defined as exercise fixation. Weight/shape concerns and exercise frequency were examined as potential mediators, evaluated both with and without eating disorder symptoms as a covariate. Method: Self-report data comprising sociodemographic details and measures of parental weight messages, body image, obligatory exercise, and disordered eating symptoms were completed by 298 young female attendees of health and fitness centres. Results: The frequency of negative maternal messages demonstrated significant associations with all of weight/shape concerns, exercise frequency, exercise fixation, and eating disorder symptoms. In the initial model, partial mediation of maternal messages to exercise fixation was evident as negative maternal messages continued to have a direct effect on exercise fixation. In the second model, with the inclusion of eating disorder symptoms as a covariate, this direct effect was maintained while mediation was no longer evident. Conclusions: The data provide further support for the association between disordered eating symptoms and maladaptive exercise, as defined by exercise fixation. Nevertheless, the importance of negative maternal messages as a key environmental enabler of exercise fixation has been demonstrated, even after the effects of weight/shape concerns and exercise frequency were accounted for. Clinically, addressing weight-related talk in the family home may reduce the incidence of problematic cognitions and behaviours associated with both maladaptive exercise and disordered eating symptoms.