Reflecting on Calorie Restriction
As noted at Ouroboros, not all calorie restriction (CR) studies produce what appear to be positive results. As the first comment demonstrates, however, we non-scientists can't assume that something as conceptually simple as demonstrating extended healthy life span in mice is actually simple to carry out in practice. "[The results suggest] that something about the conditions in the lab - including possibly something about the CR regimen itself - was not well suited to these animals, thus causing early mortality unrelated to aging, but that aging was indeed slowed (which is what it means to say that 'CR works' in these animals), so that those animals that survived whatever killed their cohorts off early on enjoyed slowed aging and a resulting extension of maximum lifespan. ... When, famously, Weindruch and Walford revised the regimen by imposing CR gradually instead of all at once, and made sure that the diet was isonutrient outside of calories and carbs, a robust and proportional effect on lifespan was observed."
Link: http://ouroboros.wordpress.com/2006/10/30/does-caloric-restriction-extend-life-in-wild-mice/