Not only did their calorie restricted diet ( CR) monkeys look remarkably younger – with more hair, less sag, and brown instead of grey – than monkeys that were fed a standard diet, they were healthier on the inside too, free from pathology.

Cancers, such as the common intestinal adenocarcinoma, were reduced by over 50%. The risk of heart disease was similarly halved.

And while 11 of the ad libitum (“at one’s pleasure,” in Latin) monkeys developed diabetes and five exhibited signs that they were pre-diabetic, the blood glucose regulation seemed healthy in all CR monkeys. For them, diabetes wasn’t a thing.

Overall, only 13% of the monkeys in the CR group had died of age-related causes in 20 years. In the ad libitum group, 37% had died, nearly three times as many. In an update study from the University of Wisconsin in 2014, this percentage remained stable.

The idea…