Dietary restriction, or limited food intake without malnutrition, has beneficial effects on longevity in some species, like rats, but they have to be weaned on it.
Despite that, a paper in PLoS Genetics claims it works in humans, probably to get mainstream media attention but will almost surely show that open access is even worse about peer review than subscription journals. Except despite claiming it works on humans, they do their study in roundworms, which in this case has zero relevance to human longevity, which means peer reviewers can say they addressed the study, while the scientists themselves engaged in hype.