Effect of 6-wk HFD on metabolic indices of CON and DEL littermates. Mice were 18 wk old and fasted for 24 h before they were killed (n = 5/group). A, Two-way ANOVA of mice switched to HFD at wk 12 indicated significant (P < 0.0001) effects of both age and genotype on body weight. Data for mice maintained on chow for 18 wk are from Fig. 2A and are presented here for comparison with mice switched to HFD at wk 12. B, Body weights for mice at 18 wk of age either maintained on chow (data from Fig 2A) or switched from chow to HFD at 12 wk of age. C–F, Additional metabolic indices of mice on HFD. Statistical analyses for B–F are by two-tailed, unpaired t tests: ***, P < 0.001; *, P < 0.05; values are means ± sem.