Thursday, September 16, 2010

Caloric Restriction

You've heard of Caloric Restriction (CR), right?

As its name suggests, CR is a dietary approach that restricts caloric intake. Done properly, it slows the aging process and extends life.

No, I'm not making this up.

Lab mice on CR can live up to 50 percent longer than if they ate a more typical diet.
The maximum life span of a typical lab mouse is 39 months, corresponding to 110 years in humans. [UCLA Professor and Biosphere 2 crew member Roy] Walford and researchers have demonstrated that mice that eat only 60 percent of their preferred diet will live as long as 56 months -- the equivalent of 165 human years -- provided they start their diets before three months of age. Although these mice are smaller than their normally fed peers, they seem to retain their youthfulness and intellects well into their extended old age. “We’ve found that a 36-month-old restricted mouse will run a maze with the same facility as a six-month-old normally fed mouse,” Walford says. “That’s a substantial preservation of intellectual function.”
Similar results are seen in studies involving all sorts of living creatures, from yeast cells and roundworms to fruit flies and spiders. Even rhesus monkeys live a lot longer on CR, with significantly reduced rates of diabetes, cancer, and heart and brain disease.

There aren’t yet any published studies on CR’s effects on the average human lifespan, but research shows that humans on CR are healthier, with lower cholesterol, fasting glucose, triglyceride levels, and blood pressure. Based on available evidence, scientists believe that a 30 to 40 percent reduction in caloric intake could significantly extend human lives.

The problem?

CR is not fun. As Michael Eades points out:
When rats live out their little ratty lives calorically restricted in their cages, they seem to show signs of depression and irritability. Primates do for sure. If primates don’t get enough cholesterol, they can actually become violent. But if you’re willing to put up with a little irritability, hostility and depression, it might be worth cutting your calories by 30 percent for the rest of your long, healthy miserable life.
Plus, as characterized by a New York Magazine writer who hosted a CR dinner party, the hardcore CR lifestyle can seem deeply bizarre:
[T]he weirdnesses are starting to pile up, and my guests are looking weirder and weirder themselves, like emissaries from a future I’m not sure could ever feel like home: a world where the food grows in vats, where the porn industry just barely survives on government subsidies, where the physically ideal male has the BMI of Mary-Kate Olsen and the skin tones of an Oompa-Loompa.

I take a deep breath then and think, A world where 80 is the new 40. And suddenly, all those little weirdnesses seem quite manageable again.

At which point Michael, having finished his helping of asparagus and Quorn, picks up his plate without a word and does what any normal person who has not eaten a truly filling meal in years would do: He holds the plate up to his face and commences licking it clean. April looks on smilingly, and though I feel another tingle of vertigo coming on at the sight, it passes soon enough.
I’m not one to shy away from trying different strategies for better health, but I have zero interest in experimenting with CR. Call me spoiled, but I’m no ascetic. Eating’s too much fun to deprive myself of its pleasures.

And I ain’t eatin’ no Quorn. (Well… maybe I’ll give it a taste, just to see if it’s as unappetizing as it looks.)

But consider this: There’s evidence that Intermittent Fasting (IF) offers the same benefits of CR -- but without having to reduce overall caloric intake.

It probably won’t shock you to learn that M and I have been playing around with a variant of IF for a couple of weeks, limiting our daily eating windows to an 8-hour period. (Sound weird and complicated? Think of it this way: We don’t snack after dinner -- say, after 6:30 -- and we delay breakfast until later in the morning -- like 10:30.)

I’ll post more about IF (and our experiences with it) soon, so stay tuned.