September 29, 2008

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."


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?


  1. Ive seen this before and know Im doomed :)

    I dont restrict and am an avowed carnivore.

    (seen this?

  2. The Bag Lady is doomed, too. But who wants to live to be 120?

  3. Really interesting and I'm glad to hear that Calorie Restriction is probably a bunch of hooey. I've tried that and lasted about 8 minutes. Calorie restriction is my worst nightmare. I think you are right, Crabby, about "all things in moderation". I have nearly the same philosophy: 'All things in moderation, except drink a lot of coffee'. Anyway, thanks for the great post

  4. I tried to read that article but it was extremely long and my attention span not so much.

    I'm in agreement with you, it seems silly to starve yourself in the name of longevity. I would much rather enjoy life for the time I'm here than to be hungry all the time.

  5. Ageing Cell does seem to be peer-reviewed - although that in and of itself doesn't make it a great journal. It doesn't mean it's a bad one just because we haven't heard of it, I think what is most likely to show this study is something worth taking note of is the number of follow up studies, so we will have to wait and see. Science is a process :)

    As for protein and veganism and so on, I've often thought I'd like to be a vegan, as it's a very healthy way to live if done right. Lots of effort goes into it though and I don't have the moral convictions necessary to stick with it. Plus I really really love cheese. And yogurt. And ice cream. And about a million other things that vegans don't eat.

  6. Give me meat and a cupcake and a bit of exercise to guide me.

    In fact, give me more protein. I have no intention to living to 120. I'm going at 93 in my sleep and if I've got a tummy filled with rare tenderloin at the time, then I go out knowing I've have a good life.

  7. I'm with MizFit in the non-restrictive/carnivore (although only non-red meat).

    However, I do it because eating 90 grams of protein ended an 8 month long ....thing (no idea what caused it or why the protein helped) where I vomited every morning (and I wasn't pregnant).

  8. Thanks for the great information, Crabby!

  9. This is really interesting! My new, vegan housemate moved in at the weekend and the second he went out that evening I (nosy parker) threw open his cupboards to see what food he had. And shrieked:

    "NO PROTEIN!!!"

    There was nary a protein source within. And he is a fit, toned and totally not-skinny chap who runs up mountains regularly.

    It made me question: do I even need protein in the first place?? I mean, I use it to feel full but that's about it. I just eat it a lot (way more than carbs) coz I think I should.

    TA x

  10. And people wonder why I am the way I am... sigh.

    Seriously though, I've always thought that protein is way overrated. Sure you need *some* but prolly not the 2.5 lbs per day Americans are puported to eat.

  11. I always felt sad when I saw the Cronies interviewed on TV.

    Luckily, I love vegan food. I was a vegan for years. Now, I eat vegan food, but I do like me the occasional piece o' bacon or a burger. ;-) Moderation in all things.

    I will say that every nutritionist I've seen associated with a major research hospital, like Duke, for example, has said protein is way overrated. So, except for my short awful stint on Atkins, I don't worry about it.

  12. Well shucks! I am all about the protein and eat a ton of calories! Does that mean I won't make it to my 40th birthday?? LOL

  13. Good post, Crabby!
    At first, when I saw the photo re rodents and humans, I thought this was a political post ;)

  14. I don't read this particular journal, but the problem is that this line of research is just way too new! Just like the calorie restriction stuff (which I think started because there's a group/village/society in asia...I think a group in Japan or China...that does this and have extremely long lives), I think I would trust it more if 1. I had read the article and 2. they (or others) could replicate their results well.

    I'm totally with the others. I would not want to live my life this way. I say quality over quantity!

  15. DOOMED! DOOOOOOOOOOOOOOMED!!!!!!!! ..... Pass the steak sauce, please.

  16. Dr. Roy Walford, who made this CR stuff popular, lived in the Biosphere and tested the restricted diet on himself. He wrote a couple books about it, if you want to read more about the CR theory.

    He himself didn't make it to 80, but that was due to Lou Gehrig's disease. That's the thing about this stuff -- you can weigh every milligram of food that goes into your body, but you might still get run over by a bus tomorrow. What the hell.

  17. Hmm, I bet the Mark's Daily Apple folks will pick up this question, but what I always ask myself is what kind of protein are they studying in these studies? Is it the typical corn-fed, chemically-laden stuff from the supermarket shelves or do they actually try to use the good stuff (grass-fed and organic)?

    Because my common sense is telling me there's probably a difference in our bodies between eating the two, but most of the studies seem to be summed up as "all meat is the same and it is BAD" (add in thundering voice of doom on "bad").

    Personal experience: I'm borderline diabetic according to the blood tests. Diabetes runs very badly on my mother's side of the family, though my father was diagnosed with it too. I have found that the less sugar and refined carbs I eat, the better I feel and I lose weight. Would I tell someone without diabetes or out-of-control weight gain to cut out all carbs? No, but I would tell them to watch out for all the fake crap (HFCS) inserted into their foods. I would recommend it for someone with my conditions.

    And please stop picking on poor Atkins. It does advocate adding back in carbs in the form of veggies and fruit first and then whole grains. It drives me crazy when people use the first two weeks of the program to sum up the entire program.

  18. SCIENCE!
    We've been looking at IGF-1 in diabetes and's related to more than just longevity. It's part of one of the major pathways in response to stress and maintaining healthy cellular activity...and that's all I'll say about that before your eyes glaze over...

    The thing is, altho the journal *is* peer reviewed, if the study were more relevant, it *would* be published in a higher impact journal (ie. one we take really seriously, as it's where all the super important, reproducable, not fishy stuff gets published). Either the study is small, not fully planned or there is something lacking for it to be published in a smaller journal. Perhaps it is interesting preliminary work, but needs more study. I'd be interested to see corroberating results from other studies comfirming this...I do believe it perked my interest enough to send me off on a search for more info tonight (oh the fascinating fun life of a researcher....we do get all the excitement!!)
    Unfortunately many studies are just published for the sake of publishing...I agree that this field is way to new to have any significance attached to it...yet.

    Plus, on a gut level, I just don't see how calorie restriction would link you to anything other than being slightly cold and grumpy all the time. Sure you'd live longer but you'd be cold and me, this is not a fair trade :)

  19. Calorie Restriction has never caused me more significant hunger, in fact, I eat more food (volume wise) that I did ad lib, and more variety. I've been doing CR for 5 years 8 months and really moderate CRON diet for 3.8 years.

    Now as to whether or not CR will extend lifespan in humans. If you refer back to some old studies done on rodents you will find that increasing protein intake, in the context of a CR diet, leads to 'longer life' in the CR group, and less disease. I'm unsure whether the protein increase (upto 50% of the diet) attenuates the reduction of IGF-1 normally seen in CR mice, but I assume it does to some extent. This is not evidence against CR at all, pretty much all previous results on humans have been beneficial. To name a findings; Virtually no risk of heart disease, diabetes or stroke. Little risk of autoimmune disease, no inflammation, less DNA damage, up regulation of genes involved in longevity (SIRT1), biomarkers that correlate with longevity such as very low fasting insulin and glucose, low body temperature, and overtime we expect less decline in DHEA. We see the same hormonal, metabolic changes. Doctor Fontana even found that those on CR have hearts that function 15-20 years younger than their ages! This is big news. We hypothesis why centenarians become 'centenarians', why they make it to that big number of 100. Well if anything is going to give you that chance it HAS to be CR right? The common characteristics that are thought to enable people to reach 100 are being found in those that go on a CRON diet. We put genetically identical mice on CR and they live upto 50% longer, this is because the longevity gene resides in us, it's just about epigenetics, turning on those genes. Right?

    Most deaths in humans is caused by cardiovascular disease, IGF-1 plays a big role in cancers and rodents DO die of cancer much more frequently than humans. I believe that this is not a negative finding at all, and people on a CR diet should really think carefully before reducing their protein intake to such low levels while on CR.

    If you want to live long enough to see real anti aging therapies. Be smart and practice some form of CR, whether it be just cutting out snacks or being on a more moderate diet. CR, not supplements or anything else is going to give the biggest chance of staying alive.

    You're welcome to check out my CR blog! Important human CR studies can be found on links on my blog too.

  20. I did a lax Atkins and South Beach thing once, which was basically me eating protein and veggies, and only having carbs if I were out at a restaurant. That kinda fell by the wayside when I discovered multi-grains.

    It's interesting, though, that while I'm an avowed meat-lover, I don't eat a ton of it. I was looking through the recipe posts on my blog, and many of them are either vegetarian or poultry based. I think that since I end up making big-pot meals all the time, beef and pork just don't do as well in them (except chili).

    I don't see myself ever becoming vegan, but I definitely eat less red meat than I used to, and I eat more vegetarian stuff as well (though I find that if I don't have protein at a meal, I sometimes will crash out at the gym later).

  21. VERY interesting stuff. I really like learning about these kinds of things.

    My question is that sure, you might live a long time (although this apparently shows that you might not- whoops indeed!), but what about your QUALITY of life? I don't want to be cold, hungry, and cupcake-less, even if it did mean I lived an extra 20 years or whatever. I want a life full of excitement!

    I am really big on having everything in moderation, and I have to say that I've never liked the superstrong promotion of protein- most people end up getting about 3x the amount of protein they need and they don't do much exercise anyways. It's the kinds of protein etc that we eat that is what we should be advocating, methinks.

  22. love the pic of the empty plate and the "where the hell is my cupcake"!!!!!!!!!

    Not a vegan......I tend to follow the everything in moderation rule except when it comes to veggies........I dive in! The protein discussion baffles me. I really love Dr. Oz and he says a small chicken breast is really about all the protein we need for a day. But in the weight loss and exercise circles, more protein is pushed. I just don't know! I do know that when I upped my protein, I broke through a plateau?

  23. I don't eat tons of meat, but would never be vegan (cheese, I love cheese).

    Wash U Medical School is an excellent research center. My researchers (who are, naturally, the best researchers in the country - maybe the world) frequently collaborate with Wash U on joint projects. I don't know the journal, but do know that it is peer reviewed and the scientists are likely highly regarded. Of course, that doesn't stop the research from being crap - even good, ethical researchers can come up with some real stinkers.
    BUT - moderation is probably still the best practice. Unless we're talking about cheese.

  24. My brother-in-law always said he'd rather eat what he likes and be happy and live to be 60 than live on rabbit food and be miserable and live to be 80. Now that he has found himself to be overweight and almost 55, he is more than happy to load up on the veggies and have dessert only once every two weeks.


  25. What smart comments, I'm learning a lot!

    Thanks in particular to Matthew the gracious Cronie who was generous enough to stop by and leave helpful information even after I teased the CR folks.

    And Clever Cranky Fitness Scientists, thanks to you folks as well! I never know what to make of these things and how seriously to take them.

    Plus I love hearing what everyone else thinks about protein in their diets because you do hear such contradictory advice about that.

  26. Thanks for posting. As a vegan I get ridiculed all the time by people telling me that it can't possibly be healthy. Ironically as a vegan I have gained more muscle than I did as a meat eater. Did the article differentiate between complete proteins and amino acid combination?

  27. I'm with purplegirl on this one.

    (And her cat face is too much!)

  28. Hmm, we're still missing a link here.

    "In animal models of longevity, extended lifespan seems to be related to this IGF-1 stuff."

    Does that carry over to humans or even all animals? Have they done any studies on that.

    For instance, anyone who has rats knows they do well on very low protein diets...if you feed them too much they get orange, itchy spots. Mine only get protein 2-3 times a week in small portions. Obviously this doesn't carry over to humans, so I'm skeptical of any model regarding protein consumption based on rats.

    If it does carry over though I am so dead.

  29. I have to admit, I am becoming a bigger and bigger believer in the idea that everyone's body is different. When I ate vegetarian, my energy levels dropped through the FLOOR. Seriously, I was sleeping 10 and 12 hours a day and I was STILL TIRED. When I added meat back in, ta-da! No more exhaustion.

    My mom? Exactly the opposite.

    Everybody's different. And I really do think that if we stopped following "diets" and stopped eating manufactured food, our bodies might actually gravitate instinctively toward what is best for us as individuals. That's just my guess, but it'd be interesting if it were true.

  30. I'm with Marste, some people do well with little protein, I'm not one of them. I need moderate protein and lots of veggies, and very little grain. Grains and I don't do well, as much as I enjoy them, especially in the form of cake, cookies, pasta and toast!

    I did great on the induction phase of Atkins as far as losing a ton of water weight (likely from inflammation from grains, I don't do well with gluten) and it showed me I just feel better off of grains. hard to do though.

    Hubby on the other hand eats a ton of carbs, not so much protein (says beef bothers him), is skinny as heck and eats all day long.

    So I'm sure that calorie restriction is a great option for some people.
    I don't know about hitting 100, even if I was "healthy", I doubt I'd be out hiking and mountain biking. Sitting around plugged into 3DTV doesn't seem all that appealing. Though if I could still say sit on a nice patio, read a good book, have a dog on my lap and a nice cup of coffee, without too much chronic pain, it would be fine.

    Great post and definitely food for thought.

  31. TK, I was with you until you got to the dog on the lap part. I'll have to get a bigger lap; I don't think my German Shepherd would fit.

    Marste, how long were you on the Veggie kick? I ask because I can relate completely -- give me a steak and I'm like a wilting plant suddenly given water -- but all the same I'm going the Veggie route. I was wondering if the body might adapt, energy-wise, after being relatively meatless for awhile.

  32. I'd rather enjoy life for a few years less than spend every day weighing my wheatgrass shots and eating quorn (seriously.) I'll look to moderation, working out, and George Burns for inspiration.

  33. I'm sort of a vague "moderation in everything" sort of chick lately, but I can't say it's based on scientific research or that it's working for me yet. It just makes some sort of sense to me.

    Also, about longevity--I wonder if that might be a bit overrated. My granny used to say "It doesn't pay to live long enough to get old."

  34. Hi, Cranky: I am relatively a new visitor here. I've been reading your blog for a little while, but this post is particularly interesting to me...

    I have tried to reduce calories or protein in various stages of my life, but neither worked. In the case of the calories, counting everything became almost a job after a while...

    In the case of protein, I don't know why, but I do feel exhausted if I don't eat at least a little protein in the day... So, I think the best is the 'all things in moderation' approach.

  35. Awesome - people keep going on an on about how I'm not getting enough protein because I don't eat meat. Thanks for the ammunition for the next argument ;)

  36. If anyone is looking for more information on the health benefits of a low-fat, low-protein vegan diet, I would recommend checking out:

    Dr. McDougall:

    and The China Study:

  37. Protein keeps my pernicious anemia in check. Twenty pounds ago, when I ran every day and lifted like a pro, I kept blacking out because I wasn't absorbing enough dietary B12. Now I am round and sedentary, but haven't fainted in months. Yay protein! And I'm sure the 20lbs will come off once I get used to running in less than optimal shape!

  38. Everything in moderation. There is no need to starve yourself..that's my opinion. Once again a great post :)

  39. I am practising CRON and I do not feel hungry at all. I eat lots of vegetables, some fruit, and a small quantity of fish.

  40. It's weird that so many people think that a quality life has to revolve around 'bad-for-you-food'. Maybe living to 120 is not ideal, but however old I end up, I'd like to get there disease free and without bathroom assistance. That would be a quality life.

    I try to limit my carbs (which means I up my protein) to limit the diseases I'll get in the future. This study is making me question that. I'd like to find out more. Thanks for the article.

  41. My life style and eating strategies are very similar to Primal, but I have been thriving on a vegan diet. I'm also enjoying food more than ever. As long as we stick with whole foods and healthy lifestyle habits, we are all going to be healthier, whether we choose to be an omnivore or a herbivore.


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