Calorie restriction in monkeys does lengthen life

A 25-year study of diet and aging in 76 rhesus monkeys shows a significant reduction in mortality and in age-associated diseases among those on calorie-restricted diets.

These findings contradict an earlier primate study, perhaps because the current study reduced the diet of the experimental group by 30% based on what the adults wanted to eat. In the earlier study, both experimental and control animals were given diets based on a standardized food intake chart — meaning that the controls may have been on a restricted diet too (an idea supported by their weight, which was at all times less than that of the controls in the current study). Moreover, the earlier study, although reported as showing calorie restriction is ineffective, had 4 of the 10 experimental group achieve the unusual age of 40+, as did 1 of the 10 controls.

The current study also saw diabetes occurring in the control group, who were allowed to eat what they wanted.