Maybe there’s no need for a fountain of youth after all. New research suggests that cutting calories by 15 percent for two years can slow the metabolic process that leads to aging and protect against age-related diseases. After just one year on a reduced-calorie diet, study participants saw their metabolic rates drop significantly. The lowered rate continued into the second year and led to an overall decrease in oxidative stress, a process that has been tied to diabetes, cancer, Alzheimer’s disease and other age-related conditions.