Sometimes it's not what you eat, but when you eat it. At least when it comes to longevity diets. For some time, scientists have known that animals kept on a strict diet live longer than their well-fed peers. But this Methuselah meal plan is no ordinary just-say-no-to-that-second-slice of pie kind of diet. To reap the life-extending benefits, some of these animals cut their calorie consumption in half. Such a diet might be do-able for captive mice and monkeys, but it would be a tough sell for people. Then, five years ago, studies in mice suggested that intermittent fasting would work just as well. These mice abstained from eating every other day, and lived longer then their gluttonous comrades—without really skimping on the total calories they consumed. Now, scientists at Kyoto University have found the same thing in worms that fasted every third day. And they found a gene that regulates the effect, results reported in the journal Nature. Like the mice, these fasting worms did not cut their total calorie intake. But they boosted their lifespan by 50 percent, and showed fewer signs of physical decline than their peers. So go ahead, enjoy that extra slice of pie. Because tomorrow's another day. To not eat.