Over at Fight Aging!, Reason spanks Oprah and sensationalist popular-medicine author Dr. Oz for promulgating unrealistic expectations about the lifespan extension benefits of CR:

Hence for a discussion of longevity, wild and unsupported claims are fair game. At the present time, the scientific consensus is that human practice of calorie restriction will not greatly enhance maximum longevity, but does greatly improve health and greatly reduce risk of age-related disease. That isn’t as exciting, however, as earlier speculation on attaining 120 year or more life spans, so the more exciting “fact” is what gets aired:

Dr. Oz says calorie restriction is the number one way doctors say we can extend longevity. “The data that we have in rodents and some larger animals now indicate you can probably extend your life expectancy by up to 50 percent potentially from doing this,” he says.

Don’t get us wrong: As Reason takes care to point out, CR is almost certainly good for you. Biogerontologists have shown that CR yields benefits at the molecular, mitochondrial, and cellular level, and it’s likely to improve human health. It is not clear, however, whether CR will extend the human lifespan to the extent seen in short-lived animal models; indeed, there are reasons to believe that it won’t.

(Qualification: the definitive studies are ongoing and haven’t been completed yet — by their very nature, they take a long time. The issue is still controversial, in the way that issues often are when the data’s not in yet. The scientific consensus hasn’t really been established; to the extent that there is one, it’s based on extrapolation from preliminary data, and the jury is still out.)

On the show appeared members of the Calorie Restriction Society, who are plugging the broadcast on their website. (I want to preface the following by saying that I generally respect CRS; I’m pretty picky about what goes into the blogroll). In light of Reason’s commentary, I realize that their website is rhetorically slanted in favor of the claim that CR confers life extension: from their motto (“Fewer calories. More life.”), to the big graph of rodent lifespan curves on the front page, to the conclusion that CR is a “proven life-extension method” (eliding the lack of definitive human data), the site is rich with implication that CR will extend longevity — a claim that hasn’t been proven.

CRS could be doing a lot better job of portraying the subject in a scientifically accurate way — toning down the implications about certain lifespan extension, focusing on the more clearly established health benefits, and giving voice to countervailing studies. Openness about the weaknesses of a theory, after all, are part of the rigorous logical testing that produces better theories. And just as with book reviews, acknowledging the negative might go a long way toward increasing the credibility of positive claims about CR.