Although it is well documented that dietary restriction (DR) increases the life span of rodents and other animals, this increase is observed at relatively high levels of DR, in which rodents are typically fed 40% less than that consumed by rodents fed ad libitum. It is generally assumed that lower levels of DR will have a lesser impact on life span; however, there are very little published data on the effect of low levels of DR on life span. In this study, we show that 10% DR increased life span to almost the same extent as 40% DR. While both 10% and 40% DR resulted in similar changes in non-neoplastic lesions, 10% DR had no significant effect on the incidence of neoplasia (except for pituitary adenoma), and 40% DR resulted in a significant reduction (40%) in neoplasia. These data clearly demonstrate that the life span of F344 rats does not increase linearly with the level of DR; rather, even a low level of DR can substantially affect life span. This rodent study has important translational implications because it suggests that a modest reduction in calories might have significant health benefits for humans.