Thread by @Mangan150

Calorie restriction (CR) has long been known to extend lifespan and healthspan in animals.

But the benefits of CR may be due to one thing: intermittent fasting.

When calorie restricted, lab animals are typically fed once a day, and they're so hungry, they eat all of their food at once, fasting until their next feeding.

That means that the benefits may be due to fasting, not food restriction.

Fasting alone duplicates many of the metabolic effects of CR.

How long would a human need to fast to get these benefits?

Probably a minimum of 16-18 hours, with longer being better.
pubmed.ncbi.nlm.nih.gov/8238506/

Fasting for this length of time allows insulin levels to decline to low levels, allowing lipolysis, or burning of body fat.

The metabolic benefits of fasting are also seen merely by restricting carbohydrates altogether.

pubmed.ncbi.nlm.nih.gov/1590373/

A ketogenic (very low) carbohydrate diet extends lifespan and healthspan in mice.

One mechanism through which it does this is mTOR inhibition, the gold standard of lifespan extension.
cell.com/cell-metabolis…

So, either regular fasting or nearly complete restriction of carbohydrates can recapitulate the effects of caloric restriction, which extends lifespan.

A combination of fasting with a carb-restricted diet would likely be the most effective for longevity and health.