Maladaptive exercise (i.e., exercise that is either driven or compensatory) is thought to momentarily down-regulate elevated fear of weight gain (FOWG). However, little research has examined associations between FOWG and exercise, and no research has measured FOWG at a momentary level or considered exercise type (i.e., maladaptive vs. adaptive). Thus, we examined both within- and between-subject associations between FOWG and exercise among individuals with trans-diagnostic binge eating.