Back in 2009, a study was published that said monkeys who received a very lean --ascetic, really -- diet lived significantly longer than monkeys fed a more generous diet. This matched with other studies of laboratory rats, and also with certain unscientific observations about humans, viz., that most of the very old people we can document in medieval societies were semi-starved monks. So the grim word went out: to live longer, starve yourself.
(If that made you miserable, too bad.)
Now the results are in from a second, larger study of monkeys, and in this study the lean diet produced no prolongation of average life span. The researchers note that just the count of calories is not the only variable here, and suggest that "study design, husbandry and diet composition may strongly affect the
life-prolonging effect of caloric reduction in a long-lived nonhuman primate."
People are reacting to this news according to their own tastes. One scientists told the Times, "This shows the importance of replication in science" and went on to claim that the earlier study "was not nearly as conclusive as it was
made out to be." Others say things like "I wouldn’t discard the whole thing on the basis of one study, when
another study in the same species showed an increase in life span. . . . I would still
bet on an extension of life."
Personally I plan to use this result as an excuse to keep gorging myself on chocolate chip cookies whenever circumstances require it.