Weight change during the study and food consumption. (A) Weight change during the study. The calorie restriction (CR) diet reduced weight (F(1,28) = 40.7, p < .0001) during the study, beginning at 12 weeks, and continuing out to 24 weeks after CR initiation (post hoc results: 6 weeks, t = 1.51, ns; 12 weeks, t = 5.92, p < .0001; 18 weeks, t = 9.05, p < .0001; 24 weeks, t = 10.9, p < .0001). Rats in CR group had slightly greater starting initial weight (t = 2.59, p < .05). This difference was unavoidable due to study design matching rats for equivalent locomotor activity mean and range. (B) Chow consumption between AL versus CR groups. Daily chow consumption varied in the AL group during the study. Data are presented as mean ± SEM. (C) Increased chow consumption in AL group during latter half of study. There was an overall 14% increase in chow consumption in AL group between Weeks 13–14 (16.2 ± 0.3 g) and Weeks 1–12 (14.2 ± 0.3 g; t = 4.84, p < .0001).