Jeff Miller/University of Wisconsin-Madison
A 2009 image of rhesus monkeys in a landmark study of the benefits of caloric restriction. The then 27-year-old monkey on the left was given a diet with fewer calories while the then 29-year-old monkey on the right was allowed to eat as much as it liked. Both animals have since died of natural causes. A new study of the effects of a restricted diet reinforces the idea that reducing caloric intake has health benefits that can extend lifespan.