Mean body weights (± s.e.m) of the four treatment groups (n=8) during each phase of Experiment 3: (i) at baseline, before diet manipulation and treatment, (ii) when two groups were food-restricted (FR) and all groups were then habituated to the activity chamber on 6 occasions followed by sensitizing (sntz) injections of d-amphetamine (1.0 mg/kg, i.p.) or saline vehicle on five occasions, (iii) during restoration of ad libitum (AL) feeding in the FR groups, and (iv) during the three weekly d-amphetamine challenge test sessions. The rates of body weight gain during the four weeks of testing were similar for rats with and without a history of FR.