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Many of us simply roll our eyes and click away when yet another medical study contradicts the last study—so what else is new? Coffee’s bad for you, until it’s good for you—and so is red wine. Antioxidants are essential, or they’re useless. And so on. Contradictory studies are an essential part of the science-news stream—and, in fact, an important part of science itself. But that doesn’t make it any less frustrating.

The fact that it didn’t, and that the two studies conflict, has unintentionally revealed a different truth about diet and aging. In both studies, the monkeys that ate less were healthier by a number of measures—and suffered far less from age-related disease. Even better, when taken together, both studies reveal a different path toward living a healthier life—one that doesn’t require self-starvation.

Over the years, various researchers have shown that caloric restriction can extend life in bats, dogs, and even spiders, and on down to nematode worms and single-celled organisms like yeast. After decades of work, it remains the only way known to increase maximum lifespan. So a lot is riding on the concept, scientifically speaking.

In the 1990s, Leonard Guarente of MIT discovered a class of longevity genes in yeast called sirtuins that appear to be activated by a lack of food. Sirtuins appeared to be “conserved” in evolution, meaning that they appear in nearly all species, on up to humans. Sirtuins are thought to have evolved as a way to enable animals to survive periods of famine. They seem to work by regulating certain metabolic pathways and reduce the amount of damage cells endure.

If researchers could somehow identify and isolate that mechanism, they’d be that much closer to some kind of longevity pill. Except for one inconvenient fact: Caloric restriction itself does not always work.

While 80 percent of the monkeys were still alive, the restricted animals had better measures of cardiovascular health, hormone levels, and blood-sugar management, an early indicator of diabetes risk. So it came as a bit of a surprise, eight years later, to find that the hungry monkeys are not actually living longer.

In fact, caloric restriction really seemed to work best in standard laboratory mice. This may be because they are predisposed to eat a lot, gain weight, and reproduce early—and thus are more sensitive to reduced food intake. (Slate’s Daniel Engber has written about how overfed lab mice have distorted scientific research.)

But in a long-awaited, well-funded monkey study like this, an “odd” result could not be ignored. Still stranger was the fact that even though the underfed monkeys were healthier than the others, they still didn’t live longer. They had lower incidence of cardiovascular disease, as well as diabetes and cancer—and when these diseases did appear, they did so later

At first, it seemed like a scientist’s nightmare: The control group is indistinguishable from the test group. In clinical trials, a result like this would kill any drug candidate. Then de Cabo took a closer look at a seemingly minor difference between the Wisconsin and NIA studies: the animals’ diets.

Furthermore, the NIA diet consisted of 4 percent sucrose—while in the Wisconsin diet, sucrose accounted for some 28 percent of the total calories.

“In physics, a calorie is a calorie,” says de Cabo. “In nutrition and animal physiology, there is more and more data coming out that says that the state of the animal is going to depend more on where the calories are coming from.”

In his study based on the two-year experience, Walford reported that the main effect of caloric restriction was to drastically lower his fellow crew members’ cholesterol levels, to 140 and below—well below the average for people in the industrialized world. Walford concluded that a calorie-restricted diet would have the same beneficial effects that he and other scientists had observed in mice.

Several studies have shown that excessive leanness—seen often in calorie-restricting humans—can be as risky as obesity. Taken together, these studies suggest that the optimal body-mass index is about 25, which is on the verge of being overweight.

But if it’s OK to be almost overweight, it might not pay to go beyond that. Another key difference between the two monkey studies has to do with the definition of “ad libitum.” While the Wisconsin control-group monkeys were allowed to stuff themselves, with the equivalent of an all-you-can-eat buffet for several hours at feeding times, the NIA monkeys were given a fixed amount of food. “You could view it as the Wisconsin monkeys were overindulging, like the rest of the American population,” says Rozalyn Anderson, a member of the Wisconsin team. Compared with           their Wisconsin brothers, then, the NIA monkeys in the non-calorie-restricted control group were arguably practicing a mild form of calorie restriction—and that, Anderson suggests, might have made a difference.

Scientists know that certain bits of DNA on the end of chromosomes called “telomeres” shorten each time the cell divides, playing a role in cell aging and eventual cell death

New research has uncovered how stress levels and diet can affect the biological age of an organism as opposed to chronological age, or calendar years.

For years scientists thought that sequencing DNA would uncover the “gene-for” almost everything, unraveling the mysteries of disease and resulting in new drugs and gene-specific treatments. It didn’t exactly pan out that way.

So to uncover the calculus within the genome, it might take some looking beyond the genome. Genes may contribute a few elements to the inner clock, but they interact within a larger scaffolding of cell processes and environmental factors.