Caloric restriction is a major component of most life-style interventions. Beyond its use as an intervention tool, caloric restriction can also serve as a scientific model to study important research questions. Caloric restriction in nonhuman animals can dramatically extend the life span, and this can also be tested in humans. In addition to conducting randomized controlled trials of caloric restriction, there is much knowledge to be gained by studying already existing conditions of very long-term caloric restriction. The Cronies, members from the Calorie Restriction Society, are one such model. In addition to studying biological markers relevant to aging in the Cronies, we can also study them to understand what makes them so successful at long-term eating behavior change. This information is invaluable given the difficulties people from the general population face in adhering to calorie reduction interventions.