Long a subject of debate—and experiments with everything from yeast to mice—the question of whether a lower calorie diet increases life span while decreasing disease has a new smorgasbord of evidence.

A 20-year-long rhesus monkey study, released today in Science, found that monkeys that consumed 30 percent less calories than average peers were one third as likely to get a age-related disease and were likely to live longer. 

Of the monkeys in the trial, 80 percent of those on the restricted diet are still alive, whereas just half of those that ate as they pleased are still around.

The diet also seemed to improve brain function into old age. “The atrophy or loss of brain mass known to occur with aging is significantly attenuated in several regions of the brain,” lead author Richard Weindruch, a professor at the University of Wisconsin-Maidson School of Medicine and Public Health, said in a statement. “That’s a completely new observation.”

Recent studies have shown that lighter diets can also keep memory wheels spinning into older age.

Weindruch, wrote an article for Scientific American called “Caloric Restriction and Aging” in 1996, in which he discussed early findings from the primate work.

But before you cut out cake entirely, the study authors note that the principle has yet to be proven to be equally effective in humans. 

Image of a rhesus monkey eating an ice cream courtesy of Manuel Millway via Flickr