Fasting plasma insulin, fasting plasma insulin-like growth factor 1 (IGF-1) and insulin sensitivity following dietary switches in male C57BL/6 mice. Fasting plasma insulin levels (A), fasting plasma IGF-1 levels (B) and insulin sensitivity (C), determined using the updated homeostatic model assessment (HOMA2) model in ad libitum (AL), dietary restriction (DR), AL-DR and DR-AL mice at 1 month, 6 months or 10 months post switch. Groups sharing the same letter within the same timepoint (that is, 1 month, 6 months or 10 months) were not significantly different to one another. Results are reported as mean ± standard error of the mean (SEM), with P <0.05 regarded as statistically significant. N = 7 to 10 per group.