Apparent prolongation of the life span of rats by intermittent fasting.

When a sufficient amount of choice food is available, labora tory rats, like many humans, eat enough to become more or less obese. As a consequence, the life span of rats feeding ad libitum, like the life span of their human counterparts, is presumably shortened. This inference is supported by the repeated findings of McCay and his associates (†̃42 a, b; †̃43) that the life span of rats can be considerably prolonged by a drastic restriction in their allowance of food. The findings of McCay and his associates practically constitute an experi mental confirmation of the claims of Cornaro (Butler, †̃05) who attributed a considerable prolongation of his life to a rigid restriction of his food intake. However, since the time of Cornaro (1464—1566)no similarly prolonged and rigid voluntary restriction of the human food intake appears to have been recorded. Obviously, Cornaro †̃s prolonged prac tice of food restriction has not been widely followed because a normal appetite tends to impel its more or less complete appeasement at reasonably frequent intervals, when sufficient palatable food is easily obtainable. Only short periods of food restriction, such as the religiously interdicted periods of food restriction or fasting of the past, would seem to be practical.