Protein: Getting Enough Without Busting the Budget

photo: Robert Huffstutter

Today we have a guest post by Andi Singer, who works with the folks over at ihmonline. She is way more of a badass than Crabby, and describes herself as: "a fitness and nutrition blogger and athlete based in the Boise area. She can deadlift 265lbs, run 5 miles, do the splits in all three directions, and kick a grown man through the wall."

Ooops: Calorie Restriction, Protein and Longevity

People are not rodents?
I coulda told you that!

Ever feel vaguely guilty because you're not one of those Calorie Restriction People who is supposedly going to live to be 120? Well, feel better: new research suggests the picture may have gotten a bit more complicated. Turns out, Calorie Restriction may not extend human lives the same way it does for rodents.

And if you're on a high protein diet? Er, you may want to give this study a bit of a look-see as well.


Bony Cronies?

There's an impressive amount of evidence out there that lab animals on very, very low calorie diets can live extremely long lives. And there is a group of Calorie Restriction People out there who apparently take this animal research very seriously.

From what I can tell, these poor guys (most of them are men, apparently), eat practically nothing and get very thin and cold but are perfectly happy living like that. There's a whole society of them, some of whom call themselves Cronies--(from "Calorie Restriction with Optimal Nutrition").

But even with their cute acronym, I've never been too tempted to join them. I'm guessing a Cronie doesn't get to eat much in the way of cupcakes. Maybe it's just me, but I'd rather have a shorter, cupcake-inclusive life than live to be 120.

Where the hell is my cupcake?

Who Cares About IGF-1?

Most of us have never heard of it, but it stands for insulin-like growth factor-1. Blah blah blah, right? But here's the deal:

In animal models of longevity, extended lifespan seems to be related to this IGF-1 stuff. And in calorie-restricted animals, their levels of circulating IGF-1 decline 30 percent to 40 percent.

Turns out in humans on Calorie Restricted diets? Not so much. The researchers took a look at Cronies who'd been on a calorie-restriction diet for an average of seven years: their IGF-1 levels were "virtually identical to sedentary people who ate a standard, Western diet."

Whoops.

If I'd been nearly starving myself for seven years for the sake of longevity and found that out? I would not be a happy camper.

(MJM is not, to our knowledge, a Cronie;
he just takes a cute angry picture)

However, there was one group that did see reduced IGF-1 levels. Guess who? The vegans!

Hooray, happy Vegans!
(art by VeganWarrior)

Protein: Not So Good for Longevity?

The researchers already suspected, from previous research, that protein consumption could affect IGF-1 levels, so they compared the Cronies, who got 23-24% of their calories from protein, to a population of strict vegans who got only about 10% percent of their total calories that way.

Result? "The vegans had significantly less circulating IGF-1, even if they were heavier and had more body fat than Cronies," said the study's lead author, Luigi Fontana. "Protein in the diet seemed to correlate with the lower levels of IGF-1."

They also took a subgroup of the Cronies and had them lower their protein intake. After three weeks, "their circulating IGF-1 declined dramatically."


Bottom Line: You Might Want to Look at Your Protein Consumption

Fontana noted that the findings were preliminary and need to be confirmed. And he doesn't recommend a drastic low-protein diet either. Instead, he suggests limiting your consumption to the RDA, which is roughly 46 grams for women and 56 grams for men. (It depends on body weight: .82 grams of protein per kilogram.)

An interesting final quote:

"It's much easier to restrict protein than to restrict calories. If our research is on the right track, maybe humans don't need to be so calorie restricted. Limiting protein intake to .7 or .8 grams per kilogram per day might be more effective."


A Little Help from the Scientists, Please?

I don't know how seriously to take this study or these recommendations.

Frankly, I've always been an advocate of moderation when it comes to nutrition: a little bit of everything is sort of my philosophy. So I never signed on to the "eliminate all those scary carbs and get all the protein you can!" approach.

But I couldn't help but notice that this did not seem to be some widely publicized study out of the New England Journal of Medicine or anything. It was done out of the Washington University School of Medicine in St. Louis and published in the online journal Aging Cell. Unfortunately, the Cranky Fitness Academic Research Library consists solely of the Google, and I'm not familiar with the reputation of these sources. I don't even know how to quickly discover if a journal is peer-reviewed or not.

I know some of you out there are actual scientists--perhaps you might have a better idea how seriously to take this?

(And I wonder if the folks at Mark's Daily Apple will take a look at this one. They're both big on science and big on protein; I don't always agree with their conclusions but they're definitely a bunch of smarties over there and if they come across it, they may have some interesting things to say.)

What Do You Folks Think? Any opinions on Calorie Restriction, High-Protein diets, Veganism, or Whatever?