Dietary restriction (DR) is often considered as a nearly universal means to extend longevity in animal species. This article argues that whether DR will increase longevity is dependent on life-history strategies. Long-lived species are not expected to live much longer under DR, contrarily to short-lived ones. However, species able to cover long distances are not expected to live longer under DR, even if they are short-lived. Human beings are long-lived and can also cover long distances: thus, DR would probably not increase their lifespan. One may wonder whether DR mimetics would have some effects in human beings if DR does not increase longevity in this species.