Schematic showing the experimental switch design. All mice (male C57BL/6) were fed ad libitum (AL) until 2.5 months of age and then dietary restriction (DR) mice underwent a step-down DR regime resulting in 30% DR from 3 months of age onwards. The dietary switch was initiated at 11 months of age, at which time the DR group had been on 30% DR for 8 months. The stippled lines denote the switch groups; either AL to 30% DR (AL-DR) or 30% DR to AL (DR-AL). All metabolic measurements were determined at 1 month, 6 months and 10 months post switch (equivalent to 12 months, 17 months and 21 months of age), except for fasting plasma insulin, fasting plasma insulin-like growth factor 1 (IGF-1) and insulin sensitivity, which were determined at 1 month and 10 months post switch only.