Aim This study aimed to determine whether the negative effects of maternal ‘junk food’ feeding on food preferences and gene expression in the mesolimbic reward system could be reversed by weaning the offspring onto a low‐fat diet. Methods Offspring of control (n = 11) and junk food‐fed (JF, n = 12) dams were weaned onto a standard rodent chow until 6 weeks (juvenile) or 3 months (adult). They were then given free access to both chow and junk food for 3 weeks and food preferences determined. mRNA expression of key components of the mesolimbic reward system was determined by qRT‐PCR at 6 weeks, 3 and 6 months of age. Results In the juvenile group, both male and female JF offspring consumed more energy and carbohydrate during the junk food exposure at 6 weeks of age and had a higher body fat mass at 3 months (P < 0.05). Female juvenile JF offspring had higher tyrosine hydroxylase, dopamine receptors and dopamine active transporter expression in the ventral tegmental area (P < 0.05). In the adult group, there was no difference between control and JF offspring in energy and macronutrient intakes during exposure to junk food; however, female JF offspring had a higher body fat mass at 6 months (P < 0.05). Conclusion These results suggest that the effects of perinatal junk food exposure on food preferences and fat mass can be reversed by consuming a low‐fat diet from weaning to adulthood in males. Females, however, retain a higher propensity for diet‐induced obesity even after consuming a low‐fat diet for an extended period after weaning.