Partial/complete explanation of CR effect?

[Guest guest]

First, we know that there are fat centenarians, so fat isn't necessarily

inconsistent with long life for some people (although they might be extreme

exceptions). Second, one-celled organisms, like yeasts, have extended

lifespans under caloric restriction, yet they don't have insulin, afaik. One

might better postulate the free-radical theory of aging in the case of yeast.

It

has also been proposed as a general theory of aging for all life forms.

Perhaps the lower levels of insulin per se, and not the leanness, are causing

the 18% extended lifespan. Insulin has multiple effects, and, in high

concentrations, acts as a growth factor associated with various disorders

(such as diabetic neuropathy, retinopathy, etc.). I believe that aging is a

multivariate process, so the various serious theories of aging probably all

come into play to one extent or another. CRON probably works through more

than one mechanism as one would infer from Walford.