I noticed a recent review paper that does a good job of summing up the present consensus on the practice of calorie restriction - eating fewer calories while still obtaining all the necessary micronutrients - in humans:
There are currently no interventions or gene manipulations that can prevent, stop or reverse the aging process. However, there are a number of interventions that can slow down aging and prolong maximal lifespan up to 60% in experimental animals. Long-term calorie restriction without malnutrition and reduced function mutations in the insulin/IGF-1 signaling pathway are the most robust interventions known to increase maximal lifespan and healthspan in rodents.
Although it is currently not known if long-term calorie restriction with adequate nutrition extends maximal lifespan in humans, we do know that long-term calorie restriction without malnutrition results in some of the same metabolic and hormonal adaptations related to longevity in calorie restriction rodents. Moreover, calorie restriction with adequate nutrition protects against obesity, type 2 diabetes, hypertension and atherosclerosis, which are leading causes of morbidity, disability and mortality.
More studies are needed to elucidate the molecular mechanisms underlying the beneficial effects of calorie restriction in humans and to characterize new markers of aging/longevity that can assist clinicians in predicting mortality and morbidity of the general population.
It should be clear by now that even absent significant longevity benefits in humans, there are many very good reasons to be practicing calorie restriction - such as a much better chance to avoid the common conditions that cut people short in later life. Every additional year of healthy life you can engineer for yourself is an extra year you can wait for longevity science to advance to produce methods of repair for the damage of aging. At the present pace of basic research, enabled by biotechnology that continues to improve at a breakneck rate, a few years is a significant length of time.