Objective The relationship between approach–avoidance motivational processes and unhealthy body change attitudes and behaviours was investigated. Method Self-reported sensitivity to rewards (SR) and sensitivity to punishments (SP) were measured for a convenience sample of 130 women, aged 18 to 40 years, along with measures of disordered eating symptomatology and exercise dependence. Results Together, SR and SP significantly predicted variance in drive for thinness (21%), bulimia (17%), and obligatory exercise (7%). These relationships were partly mediated by internalization of the thin ideal, body comparison, and subjective importance of achieving one's ‘ideal’ body and of avoiding one's ‘worst possible’ body. Interestingly, body dissatisfaction partly mediated the relationships involving SP but not SR. Discussion The results suggest that an underlying sensitivity to punishments, but not rewards, can manifest as a ‘fear of fatness’. Both of these motivational traits can increase the salience of self evaluations, and thus indirectly contribute to unhealthy body change attitudes and behaviours.