A 20-year study found that Rhesus monkeys fed a nutritious, low-calorie diet have fewer age-related diseases than counterparts on a normal diet, researchers report July 10 in Science. Since both groups of monkeys are on a very healthy diet, people who go from a high-fat Western diet to a healthy, restricted diet may experience even greater health benefits than seen in this study. Over the course of the study, monkeys on the full-calorie diet were three times more likely to die from an aging-related disease than monkeys that ate 30 percent fewer calories, the researchers found.