This might come as "discouraging news" to a country with 200 million people who are overweight or obese, said Karen Kaplan in the Los Angeles Times. Researchers who tracked 76 rhesus monkeys for as long as 20 years found that the risk of death from age-related disease—such as cancer, heart disease, and diabetes—fell by two-thirds for monkeys that consumed 30 percent fewer calories than monkeys on a normal diet. And that's not all—the monkeys that ate less had less atrophy of gray matter in their brains, and "they even looked less wrinkled and flabby."

"Scientists have long known that dramatically cutting calories can extend the lives of yeast, flies, and rodents," said Carolyn Y. Johnson in The Boston Globe. But this study, funded by the National Institutes of Health and published in the journal Science, is the first to show that the same rule holds true in "a genetic cousin of humans." Still, some biologists point out that the scientists left out deaths in dieting monkeys not attributed to aging—so it's too early to say whether this means monkeys, or humans, can add years to their lives by slashing calories.

Even the scientists who conducted the study cautioned against reading too much into the results, said Nicholas Wade in The New York Times. But it's clear that the effects of a low-calorie diet on aging in monkeys has more meaning to humans than previous studies showing similar results in mice, which respond differently to treatments for diseases such as cancer. So rhesus monkey studies provide the best picture yet on "the prospects of finding drugs that might postpone the aging process in people."