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. doi: 10.1038/nature11432 [published online August 29, 2012]).
Young monkeys on a caloric restriction diet also did not have an increased life span, but they experienced several health benefits, including improved immune function and lower cancer incidence.
Hampton T. Calorie Restriction in Monkeys. JAMA. 2012;308(13):1310. doi:10.1001/jama.2012.13153