The process of aging is associated with progressive remodeling. The age-dependent remodeling process mainly affects anthropometrics and endocrine function, which subsequently impact metabolic factors. In some individuals, e.g., the very select group of healthy centenarians, the remodeling process is successful. The reasons why centenarians are able to reach the extreme limits of human life span are still largely unknown; however, several studies in humans have shown that longevity is associated with a significant improvement in glucose handling - mainly, a rise in insulin sensitivity and a decline in plasma insulin-like growth factor I levels.
Caloric restriction seems to be the best positive modulator of metabolism to achieve longevity. Other specific metabolic adaptations, even those genetically induced, might also play a role in the health of centenarians.