Self-regulation is a critical ability for maintaining a wide range of health behaviors, especially in preventing overeating and weight gain. Previous work has identified various threats to self-control in the eating domain, chief among which are desire strength and negative affect. In the present study, we examined individual differences in college-aged dieters' experiences of these threats as they encountered temptations to eat in their daily lives, and tested whether these differences characterized sub-groups of dieters with divergent self-control outcomes. Specifically, 75 dieting females (age range: 18–23) participated in a combined functional magnetic resonance imaging (fMRI) and experience sampling study. Participants passively viewed food cues during a fMRI session, and then reported their daily eating behaviors for one week via ecological momentary assessment. We examined the characteristics of dieters who exhibited the most favorable combination of the aforementioned factors (i.e., low desire strength and positive mood) and who were thus most successful at regulating their eating. These dieters endorsed more autonomous reasons for their self-regulatory goals, and during the food cue reactivity task more readily recruited the inferior frontal gyrus, a brain region associated with inhibitory control. We suggest that these motivational and neural correlates may also be implicated in self-regulation of other important health behaviors.