Dietary restriction (DR), a reduction in nutrient intake without malnutrition, is the most reproducible way to extend lifespan in a wide range of organisms across the tree of life, yet the evolutionary underpinnings of the DR effect on lifespan are still widely debated. The leading theory suggests that this effect is adaptive and results from reallocation of resources from reproduction to somatic maintenance in order to survive periods of famine in nature. However, such response would cease to be adaptive when DR is chronic and animals are predicted to allocate more resources to reproduction. Nevertheless, chronic DR can also increase the strength of selection resulting in the evolution of more robust genotypes. We evolved Drosophila melanogaster fruitflies on ‘DR’, ‘standard’ and ‘high’ adult diets in replicate populations with overlapping generations. After ~25 generations of experimental evolution, male ‘DR’ flies had higher fitness than males from ‘standard’ and ‘high’ populations. Strikingly, this increase in reproductive success did not come at a cost to survival. Our results suggest that sustained DR selects for more robust male genotypes, which are overall better able to convert resources into energy, which they allocate mostly to reproduction.