"Calorie restriction in rhesus monkeys starting at older ages does not increase survival but does improve metabolic health, according to a study initiated in 1987 by National Institute on Aging researchers and their colleagues(Mattison JA et al, Nature, published online Aug 29, 2012).
Young monkeys on a calorie restriction diet also did not have an increased life span, but they experienced several health benefits, including improved immune function and lower cancer incidence.

The findings contrast with those of other research showing that calorie restriction can extend life span in lower organisms of various species, as well as an ongoing study at the Wisconsin National Primate Research Center that reported improved survival along with improved health associated with calorie restriction in adult rhesus monkeys(Coleman RJ et al, Science, 2009; 335:201-204).

The authors of this latest study propose that the effects of calorie restriction in long-lived animals are not straightforward, with study design, husbandry, and diet composition possibly playing influential roles.
They add that it is important to continue to compare findings from ongoing calorie restriction studies in monkeys to determine the mechanisms behind the improvement in health that appears to occur regardless of effects on survival."

ㅡ JAMA, October 3, 2012