Doctor's Note

That same data set that compared plant eaters to marathon runners was also featured in Hibiscus Tea vs. Plant-Based Diets for Hypertension and Arteries of Vegans vs. Runners.

More on the caloric consumption and longevity:

What exactly is IGF-1 and what is the relationship to animal protein consumption? View my 9-part video series:

  1. IGF-1 as One-Stop Cancer Shop
  2. Cancer-Proofing Mutation
  3. The Answer to the Pritikin Puzzle
  4. How Plant-Based to Lower IGF-1?
  5. Protein Intake & IGF-1 Production
  6. Animalistic Plant Proteins
  7. Too Much Soy May Neutralize Benefits
  8. How Much Soy Is Too Much?
  9. Plant-Based Bodybuilding

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  • rajkhosla

    This is a great informative video. Thanks for this Dr.

  • veganchrisuk

    This latest research appears to contradict earlier Caloric Restriction (CR) results re the reduction of IGF1 (for example, “Eat, Fast and Live Longer” – Michael Moseley BBC). I will personally sit on the fence on this one until all the numbers are crunched, notwithstanding the fact that I practice both veganism and about 16hrs of fasting per day.

    Any additional info re the length of CR in hours required to reduce IGF1 would be appreciated.

    • Pat

      I don’t see any contradiction, Veganchrisuk. People in the CR society limit their calorie intake to around 1800 calories a day- and in my mind, they look terrible-way to skinny! They’re probably cold all the time, can’t exercise much and get sick often. I wonder if they have any libido or good bone and muscle mass- although I understand that their blood lipid levels are as good as a vegan’s. What you practice- and I practice it too, is called intermittent fasting, not to be confused with calorie restriction. I’ve read that it may result in healthy brain aging and it’s possible that it promotes autophagy- the removal of garbage from the cells. The benefits seen in CR seems to be in the body producing ketone bodies from the breakdown of fat, which also happens around 16 hours of fasting, but without depriving yourself of the daily calories you need. Thanks for the Michael Moseley reference; I’ll have to read it.

      • veganchrisuk

        Hi Pat – thanks for the reply. I certainly think you will find the BBC documentary very interesting – I’ve just searched for it and it’s available free on a site with the intitials D M (not sure if I can promote it here). The Cronies (calorie restrictors on optimal nutrution diets) do appear to be aging better than the average person, however I have not seen any comparisons made re vegans or vegetarians therefore I wouldn’t be so quick to discount them, as like all things in life, certain factors affect different people in a variety of ways; what will work for you may not necassarily work for me, and so on.

        Re the IF, I think you’ve got me slightly confused – what I practive is a daily regime (last meal about 7-8pm, next meal about 12 midday (following a gym session). If I were an Intermittent Faster I would be fasting on an intermittent/irregular basis – you say potatoe, I say potato…..

        If you’re interested in science as well as nutrution you will also be able to find other BBC Horizon documentaries re The Wonders of the Solar System, and The Wonders of the Universe – fortunately for me they are presented in laymans terms, whereby you are presented with such facts as the human body being comprised of 99.9999% empty space due to the composition of the atoms that we are made of. Or that by jumping from the height of 2 metres on a neutron star (exploded sun), by the time you hit the ground you’d be travelling at 4 million miles per hour – if only we devoted more money to science and the pursuit of knowledge.

      • Golgo33

        The key phrase being “in my mind”. It is all in the mind.

        Cronies who do it right follow a healthy diet that is based on minimally processed roots and tubers, starchy vegetables, grains and legumes, with the addition of vegetables and fruits. These foods are low in caloric density, high in nutrient density and high in satiety (potatoes and sweet potatoes are by far the most filling foods). Cronies eat whenever hungry, until they are comfortably full. They are as lean as possible within the normal range of body weight, as the WCRF/AICR recommend. They wear extra clothing for warmth instead of extra fat reserves, but they are more comfortable when it’s hot/warm too. By definition, optimal nutrition is essential for optimal energy levels, immunity, sexual function and bone and muscle mass.

        Caloric restriction is the most powerful intervention to extend healthy lifespan in mammals.

        The longest-lived populations have all practiced caloric restriction.

      • nutritionmama

        Hey Pat – It’s interesting to read about fasting from your perspective. I am in a Master of Nutrition and Integrative Health program right now. I’m studying physiology, and I can’t see a benefit to fasting – except that it creates a routine that is satisfying to you. However, I’m no expert (yet! :-) ). Mostly I wanted to write to correct your information about ketones, as they are not made from the breakdown of fat. Ketones are formed from the breakdown of amino acids to feed the cells energy when glucose availability is severely restricted. Amino acids are used for hundreds of physiological functions, including structural – bones and muscle. It is from muscles (skeletal muscle, heart, and kidney muscle) that the body sources the amino acids it needs to make ketones. They are particularly provided to the brain, nervous tissues, and kidneys, which have the enzymes that can transform them into energy. The body produces ketones when there are not enough fatty acids to recreate into glucose, or when that limited supply of glucose must be used by red blood cells (as that is the only source RBCs can use for energy). It’s the body’s emergency back-up for energy resources. It’s certainly useful, but it’s easy to let get out of hand if utilized too persistently.

        Ketones are formed to produce energy under certain, usually extreme, circumstances, mostly during severe carbohydrate restriction, starvation, or when diabetes is present. The risk of using ketones as a dominant energy source instead of glucose and fatty acids (as our bodies are designed to do) is that it can progress to ketoacidosis, resulting in lowered blood pH (acidic blood), nausea, and even coma and death. So, it really is wise to provide your body enough fuel along and along so that your body has a steady, regulated stream of glucose. Adipose tissue balance is created when 1) food provides glucose for the few hours after eating. 2) Then as those glucose levels dip during the post-absorptive state, the body accesses fatty acids in adipose tissue to provide the steady levels of glucose needed for continued energy through the day. Then it’s time to eat again. Insulin and glucagon provide this energy homeostasis in response to our food intake. Excess glucose, fatty acids, and amino acids are turned into adipose tissue (fat), so that’s where amounts of macronutrients needs to be considered to create adequate energy without packing on the pounds.

        Nevertheless, there has been increasing evidence that extending the post-absorptive state (which is short of fasting, which technically lasts 24 hours) contributes to long term brain health and longevity. It sounds to me as though what you and veganchrisuk practice is the extension of the post-absorptive state. There’s got to be a snappy term for that!

        • Ed

          Actually, ketone bodies are created by the breakdown of fatty acids, (ketogenesis), like Pat said:

          The human body doesn’t convert fatty acids to glucose in any appreciable amounts.

          Perhaps you’re confusing ketogenesis with gluconeogenesis, which is the production of glucose from glucogenic amino acids?

          • nutritionmama

            Hi Ed, thanks for your response. As I mentioned, I’m still working on becoming expert – clearly not there yet! :-)

            I’m pretty sure I understand gluconeogenesis, so I don’t think that I mixed up the two. In looking back over my text and notes, I think the presentation didn’t draw enough of a distinction between the use of fatty acids vs. ketogenic amino acids. The concept of ketogenesis is obviously still new to me, so I didn’t pick up on the primary use of fatty acids in that process. Still, I understand that under extreme conditions when fatty tissue is used up, lean muscle tissue is converted for energy as amino acids are taken from them for ketogenesis. Those are not the conditions of the post-absorptive state or even fasting.

            My text describes that fatty acids are tapped by “many cells” during the post-absorptive state as an energy source to produce enough glucose for red blood cells (gluconeogenesis). “Many cells” is pretty vague, but it does make it sound as though fatty acids are routinely tapped to make glucose. Also, during the post-absorptive state, declining insulin and rising glucagon stimulate lipolysis and the release of free fatty acids into circulation. At this point would you say that the fatty acids are being used for gluconeogenesis or ketogenesis? Ketogenesis is explained by my text as being stimulated primarily in response to starvation (starting as one hits a state of fasting, which is much longer than the post-absorptive state), persistent low carb intake, and diabetes.

            Under the fasting state, the body must rely on gluconeogenesis when glycogen is depleted. Muscle tissues contribute amino acids, lactate, and glycerol to that process, and adipose tissue contributes fatty acids. I’m guessing this is the point where I lose touch with what happens next. I know that ketogenesis begins when glucose sources run dry.

            Thanks for clarifying and enhancing my education! I think that I will copy this post and put it on my class forum as well. This is one of the few spots in my physiology and macronutrients courses where I still need to shake out misunderstandings before I move ahead. I’m studying nutrition mostly to be able to work with people with allergies and mental illness, but the facet of energy metabolism is critical to any study of nutrition, so I need to be sure I’ve got it!

      • Eva

        I’d say, vegans today are not skinny exactly, they are as they should be. I have seen loads of old black-and-white movies where we can see how people actually looked like in the past, like 50-60 years ago for example. Some women were chubby, others and most of the population, including men, were extremely skinny and bony. And I am not talking about malnutrition, I am talking about structure, they looked healthy, they smiled, etc… So I think the human body is not supposed to be that meaty, if I can say so, to be that heavy (if you were in the wild after a dear would you be even able to run after it if you weighted 80 kg… tough job, I think :) ) These latest videos here were really interesting, I always watch them after receiving the daily newsletter.
        And finally, I never count my calories, but when it happens to do so in days when I had huuge appetite and didn’t restrict myself, I would go beyond 2000 calories per day, in the end I feel bloated, heavy, even breathing is a bit hard…. thanks, but I’d stick to below 2000 calories/day… my best days are around 1500-1800… I can’t even understand how other women are supposed to eat 2000+ daily (and most people eat more than that)… I’d be permanently obese…

        In most japanese regions, and I believe chinese too, people are always skinny because they have smaller portions. Oh, and in some japanese rural areas people live the longest compared to other countries. So, again… I’d stick to lower calory intake. I won’t starve on 1800 calories, but raise the chances of being healthier at older age and maybe even living a bit longer than average. Physical food is not the only food in this world.

        I know my post gets very long, but I’d like to share something else. I love mountaineering. My country’s mountains are just breath-taking, and every time I go there, strangely, the scenery being that beautiful, I honestly forget about the food. I enjoy the trekking and climbing so much that it fills me constantly with joy and adoration for this beautiful nature… and then… when after hours and hours of climbing, I sit after all to have some lunch or such, then the food tastes the best!!! It never tastes so good when at home or work, or the city…. never…. while in the nature, after hours of beauty, the food is almost godly… although it may be just a silly sandwich… In such trekking days I may even eat lest than usual and the feeling of tiredness is actually even pleasant…

        Since then I know that eating physical food is not the only thing.

      • kath

        i dont limit calories because plant calories are already low and i eat plenty (i am Polish with big appetitie). At 65, I go to the gym 6 days a week for strength and cardio. Did my first sprint triathlon at 65 (3rd place–only 3 women in my age group LOL). I dont get sick and can chase my grandkids around like crazy. Dont generalize

    • Charma1ne

      Thanks very much for that BBC Moseley link. I watched the video and found it interesting.

      • veganchrisuk

        Good, I’m glad you liked it…..

        Apologies for the late reply BTW

  • HemoDynamic, M.D.

    I love that I can get up in the morning and in 4 to 6 minutes learn more information about nutrition than I learned in my whole seven years in medical school and residency. That’s not saying much because the residency programs should be teaching this but it is truly awesome that you put this information together so I can pass this information along to my patients!
    Especially during this month of Noshember. (No Shave November)

    • Lookin’ good Doc!

      • HemoDynamic, M.D.

        You are too kind. That pic ended up being too big. Your beard looks better!!!

        • About those well-trimmed beards! Do women like kissing you? Of course, they like you You are both handsome and wonderful men from whom I have learned much, but I am asking about the greyed thistle-texture of the beards? I could not resist asking!

          • HemoDynamic, M.D.

            You say such wonderful things and you are too kind.
            Actually I have never grown a beard before. It’s only on my face because of the Noshember idea which I use to bring awareness to cancer and reducing ones risk by eating plant based.
            Interestingly, I wasn’t going to do it but my wife liked it so I will keep it going but you are right about the texture. She doesn’t like the feeling of the thistle-texture on her. ;(

    • tbatts666

      It is sort of embarrassing.

      I am in my second year as a med student. We know nothing about nutrition. It isn’t covered on step 1 (that looming standardized test) so we have trouble finding the motivation.

      Without dr g’s videos my nutritional knowledge would be terrible.

      • HemoDynamic, M.D.

        Some residencies are changing but not fast enough.
        I had to stay in the “fire” (residency) until I was able to get out and make my own “water”.

        Hang in there because it is worth it! There is nothing better than watching your patients actually reverse their chronic diseases and improve their quality of life!!

        • tbatts666

          I have some years of training ahead.

          In my education I’ve only really heard veganism be mentioned as a connection with B12 deficiency.

          How did you improve your motivational interviewing, patient interaction type skills? I still quite often leave patient interactions feeling like the visits are unfocused.

      • Ike

        When you have chronic disease staring you in the face daily, the same people coming back, and you know you are not helping them, believe me you will find the motivation, (if you love medicine and people) otherwise you might be tempted to quit medicine…

        • tbatts666

          Oh I am concerned about it.

          Motivational interviewing is a practiced skill.

          It’s hard to figure out all the social causes of disease going on in people’s lives. I hope some things I’ve said in patient interactions have helped people make “better” lifestyle choices. But when someone is weighed down by so much of the stuff of life I’m not sure where the best place to start is.

          • HemoDynamic, M.D.

            You start where the patient is.

            Meaning you meet them wh10 PMere they are. Some people will never be able to accept a lifestyle Change and that is OK. I always find ways to bring up plant based eating and “test the waters” so to speak.

            If I feel like someone is staunchly against changing their lifestyle I don’t push it (you’re meeting them where they are). But if they give me an inch, I will take a mile and educate them about their personal benefits if they change their eating habits.

            This means if they come in for diabetes u ask them if they would like to get off their medication regarding diabetes. I don’t tell them about lowering their blood pressure. You see? I met them where they are. That is what u call motivational interviewing

      • someGuyOnTheInternet

        At least you know enough to know you don’t know anything. Most people haven’t even learned that much. :)

    • Pat

      Since we “nosh” so much on turkey day, we have other reasons to call the month Noshember.

    • Hana

      Thank u doctor, it is so nice to see sometime for change some open minded M.D.

  • Pat

    The last statement in this video:

    “It’s not how many calories we eat, Protein intake may be the key
    determinant of circulating IGF-1 levels in humans, and so reduced
    protein intake may become an important component of anticancer and
    anti-aging dietary interventions.”

    doesn’t make any sense in light of which tells us that vegens get as much protein as everyone else. I myself, get about 80 grams of protein a day, much of it from beans. And I don’t think it would be a good idea to stop eating beans to reduce my protein level. So, it can’t be the protein that reduces IGF-1 in vegans, unless the quality of protein in vegetable food is different somehow than in animal “foods.” Other videos indicate that vegans get less leucine and methionine, two components of protein, than do meat eaters. Perhaps that, along with reduced body fat is the reason for the greatly reduced cancer rates in vegans.

    • Frank

      Animal protein and isolated soy protein will both increase IGF-1 levels, whereas regular plant protein will not. So avoid anything made out of isolated soy protein such as soy “chicken” and protein bars.

      • NitaBoc

        What about whey isolate?

        • Amy Johnson

          Whey is dairy product disguised by a different name. Any isolate is processed, and it is best to steer clear of processed foods in general. Being that it is a dairy product, it is also a cancer promoter. If you haven’t seen “Forks Over Knives” (the documentary on Netflix), I highly recommend watching it.

      • Corina-Aurelia Zugravu

        from where do you take this fact?! it`s not true at all, soy protein are ok, in reasonable quantities, of course…

    • Catherine J Frompovich

      When I studied nutrition I learned about complementary proteins, which are plant proteins/amino acids that, when combined, are equivalent to animal source proteins, e.g., peas and rice combined can equal animal protein amino acids. Not much is said anymore about complementary cooking and combining at meal time. It is my opinion that many are under the impression that plant protein is high quality protein, which is not factual UNLESS or UNTIL complementary cooking and eating is practiced.

      May I suggest this site for a ‘crash course’ in complementary proteins.

      • Laurie Masters

        Hi, Catherine. The complementary protein mythology has long since been proven incorrect. See here:

        • Jackie Thomas

          yeah, Catherine. I thought I read about a year ago that this thing is a myth. Glad to see you dispel it.

          • Corina-Aurelia Zugravu

            It is not at all a myth. You don`t have to eat them at the same meal. However, you have to eat complementary proteins.Just think cereals don`t have enough lysine. Without legumes, which are complementary to grains and nuts, it will be very hard to fulfill your necessities in essential amino acids.

          • Thea

            Corina-Aurelia: The information on the following page contradicts your post. I don’t believe there is anything in the following article that is disputed. As long as you eat enough calories in a whole plant food diet that includes more than just fruit, you don’t have to worry about protein combining or getting enough of certain amino acids. As explained in the following article, the person who originally came up with the idea of needing to worry about complementary proteins has long since retracted it:

      • VeggieRD

        Hi Catherine! Thankfully, we now know that carefully matching complementary protein within meals is not necessary. You may find this resource from the vegetarian dietetic practice group of the Academy of Nutrition and Dietetics informative:

      • Thea

        Catherine: You have already gotten some great replies to your post. Here is another resource that is wonderful for understanding the big picture about protein. In other words, it does more than dispel that one myth. It’s a very good education about protein in general:

  • Misterimpatient

    Is IGF-1 a standard test my doctor can order AND, as testing procedures vary leading to varying nominal results, how would we best use that information? I would guess we’d want our IGF-1 levels to be below normal, as normal would be what a western diet produces.

    • IGF-1 testing (also known as somatomedin C) is not routinely used in clinical care. It’s possible that reference ranges haven’t been established, and, much like a blood glucose level, one isolated reading wouldn’t be very informative due to normal fluctuations. It is occasionally used in some pediatric diseases (to which I cannot speak), but generally, this test is only used in research protocols.

      • Misterimpatient

        Thanks Kerri. I am a bit of a numbers nerd so I like stuff like this. I take your point that a single data point is not useful, but, if the test were inexpensive (unlikely) and available I would have it done as a curiosity, even out of pocket. Also I have another interest in the test. My family doesn’t sucomb to heart disease. Cancer is our achilles heal, and, in the first instance brought me to veganism 4 years ago. Since then, the moral and ethical issues have made it a lifestyle easy to maintain.

  • bobluhrs

    It would be really useful to have a video on protein, less from the chemistry building blocks (amino’s, etc) and more from the practical dietary viewpoint. What plant proteins can be listed as best and worst? It seems there’s some question about soy-derived products vs animal proteins, and this question is always coming up. Dr Greger’s videos and blogs are the first thing I do in my email every day, and I even post them on Facebook, contribute, buy the DVD, etc. It’s wonderful, I urge everyone to connect up, give and take from this bounty.

    • Thea

      bobluhrs: I totally agree with you that NutritionFacts is awesome. Thanks for your post.

      Concerning the topic of protein: I think you would find the following articles to be real eye openers. By the time you work your way through these two articles, you will have your answer, and so much more.
      Why Protein Is A Non-Issue:

      To fill in yet some more details is Dr. McDougall article from December 2003:
      You might also check out the January 2004 newsletter article, Protein Overload.

      Hope that helps!

      • HemoDynamic, M.D.

        Thea, Thanks for posting the, “Why protein is a non-issue” article. I’ve never seen that article before and it is very good.

        • Thea

          Your welcome! That article really helped me when I was first thinking about going vegan. It really helped allay my fears about protein concerns so that I could focus on what really matters.

  • refusenik2012

    A plant based diet may unintentionally create calorie restriction. How about the feast/famine complex. A person in famine may develop fat cells to survive. Isn’t a base number of calories necessary? Granted that eating fruit and vegetables may seem like a feast but does it meet minimum required calories. Also, fat cells carry estrogen but, don’t plants have estrogenic reactions as a defense mechanism? I have been a vegan for the last 20 years.

  • Gerald

    More great information! One question re. plant protein: As a vegan bodybuilder, I have a pea protein drink ea. day. Does that form of plant protein also increase IGF-1 levels?

    • olaf

      i was about to post an almost identical question but then just in time saw this. I’m not body building but i’m a long distance runner and have a protein enriched shake a day, containing about 30g of plant based protein isolates (pea, brown rice and hemp protein) and was wondering as much as Gerald if those protein isolates also have the potential of increasing IGF-1 levels?

      • Neil

        Only animals produce IGF-1. But plant protein, specifically soy protein, also seems to trigger our body (muscles and liver) to make it:

        Dr. Fuhrman suggests that if one wants to eat plant protein isolate (although one doesn’t need it; eat more whole plant foods that are high in protein rather than processed powders) then pea protein is a good choice (as is hemp and rice).

        In addition, plant protein in general (excluding soy apparently) seems to bring our IGF-1 levels down:

        They believe the issue with soy is that it’s amino profile is too similar to animal protein.

        • olaf

          very reassuring :)


      • Dylan

        I’ll 2nd that Olaf. I too am very active and prefer to use pea protein from time to time. All the research I have done has since shown nothing but good health benefits and no adverse change in cardiovascular markers and common blood panels. Nevertheless, I am not a researcher. If there is other evidence out there, someone please post.

        • Dave

          I use pea protein as well.
          PS. Combine brown rice and pea proteins :-)

      • Carol Demas

        Methionine-restricted mice have lower serum IGF-I, insulin, glucose, and thyroid hormones. If you wish to downregulate IGF-1 levels, you could consider lentil, kidney bean, adzuki, and split pea instead of soy. To be prudent, you should still meet your RDA for methionine. We don’t know what level of lowered intake is safe in the long term. You can track your micronutrient intakes at a number of free sites (,

        Miller RA, Buehner G, Chang Y, Harper JM, Sigler R, Smith-Wheelock M.
        Methionine-deficient diet extends mouse lifespan, slows immune and lens aging, alters glucose, T4, IGF-I and insulin levels, and increases hepatocyte MIF
        levels and stress resistance. Aging Cell 2005;4:119–25.

    • This is not a snark, but why does someone need more protein when they are physically active? I can understand more calories are burned but why do you need more than the usual proportion of protein found in whole plant foods? thanks

      • Gerald

        I include a protein drink for three reasons: one, observational: vegan bodybuilders are smaller than non-steroid carnivore bodybuilders (one big difference, protein consumption, I think); two, research: lots on protein amt & synthesis & muscle growth (as Casey Stengel said, “You can look it up”; three personal: I feel better & my muscles are a tad bigger with my protein drink. Your observation is reasonable, Coacervate, & I’ve wrestled with it myself, but I do think I’m a bit more buff with the protein drink (I’m not a big guy — 165 lbs. — so I want all the power & muscles I can pack in & on)

      • olaf

        There are a few reasons why I add some extra protein to my
        post workout shake. Not that I can quote any studies here but it appears that
        there’s a window of about 30 – 90 minutes after a strenuous workout during
        which the body is more ‘open’ to absorb nutrients. So I mix carbs (bananas,
        dates, etc) with oat milk, some blueberries if I have some, raw almonds, once
        in a while even leafy greens as spinach and 30g of protein powder. That is much
        quicker done and digested than boiling rice and lentils – so it can be regarded
        as a convenient thing.

        It does fill me up and it also lasts much longer as if I skip
        the protein. Without the protein, I’m very often extremely hungry within 1,5 –
        2h max after that shake.

        Above average workout does call for above average nutrient
        intake. So I thought that 30g of extra protein won’t hurt but this particular
        video raised some doubt.

        • Gerald

          I, too, subscribe to the “window open for absorbing nutrients.” There is research supporting it (I’ve come discussions of it in bodybuilding magazines), but I’ll also add, just with respect to personal experience, that when I’m lifting, I sip my pea protein drink (mixed with pomegranate juice, a banana) throughout my workout, and it definitely adds endurance & zip to having a good workout, in contrast to times when I don’t have the drink. When I do aerobic work (powerwalking) every other day, I have the drink after the workout, primarily for the reason you explained.

        • Neil

          Hey, Olaf. Anecdotal evidence aside, it seems, according to this study, that the belief of an optimum after-workout window in which to digest protein is an urban, or rather gym, myth:

          What Coacervate may have been getting at is that we can get all the amino acids we require, and can use, through eating whole plant foods. If we exercise more, we burn more calories, requiring us to eat more. If we eat more whole plant foods as a calorie source, we naturally consume more amino acids (aka proteins).

          Here is a very in-depth article on protein requirements from the World Health Organization:

          It states:

          “A more active person expends greater amounts of energy, consumes greater amounts of food, and hence has a higher absolute level of protein consumption.” p.12

          And, as this study out of MIT shows, it is a myth that we cannot easily get our protein requirements from plants. It is also a myth that we need to mix protein sources at the same meal. Our body stores, intracellularly, amino acids that our bodies do not make. So when we eat foods with these limiting amino acids, like lysine, our body stores them, and uses them as needed. See page 1209S, last full paragraph here:

          The other critical misconception is that we, as a society, see nutrition as compartmentalized: proteins, carbs, minerals, etc. We don’t realize how that there are thousands of chemicals and hormones and micro and phytonutrients at play in ways we may never understand. Muscle formation, in other words, depends on so much more than just taking in more protein because there is so much involved on making muscle tissue. Here is one more quote from the WHO study:
          “The pathways of amino acid metabolism and interchange are critically dependent on adequate micronutrient status, and hence upon the amount and quality of food consumed. *** In addition, with either supplementation or food fortification, disposal of any excess consumption of micronutrients can impose . . . stress on the body.” See page 12.

          In other words, pounding our body with supplements (like protein isolate in any form) in excess of what we need only makes our body work harder to get rid of the excess. This doesn’t happen if we just get our calories (and hence amino acid requirements) from whole plant foods.

          Point being that supplementing your diet with more protein is not needed. But since it is plant protein, there is no harm, whereas doing the same with animal protein (whey, dairy, meats, etc.) does have harmful effects.

          • Thanks for putting it into words. On a personal level my family and closest friends are so concerned that äm I getting enough protein”. Cripes, I’m building green houses and installing water pumps around the farm…what do they want? I’ve never felt better. I think some confuse vegan with Whole Foods, Plant based. The two can be lightyears apart. WFPB = health. Blood simple

          • Neil

            No problem. I enjoy researching this stuff. I always learn something. You can have your family read the MIT article on protein myths. Also, show them these two vegan/plant-based athletes, just as examples: MMA fighter Mac Danzig, and one of the world’s strongest men, Patrick Baboubian, who recently set a world record in one event. These guys can achieve and maintain their endurance, strength and muscle mass although they are training harder than 99% of the population ever will. In other words, if they get enough protein without animal products, I’m sure the rest of us will be alright.



            I agree that vegan and whole food, plant based (WFPB) are different. I try to make the distinction with people all the time. They see that I don’t eat animal products, and they say I’m vegan. At the most I could say I eat like a vegan almost all of the time. Vegan, to me, however, means a lifestyle based on the moral and ethical issues behind the killing of animals for food and clothing (no wool, no honey, no leather, etc.). Whole Food, Plant Based, for me, means a primary focus on my personal health through the consumption of whole plant foods, although secondary issues are definitely environmental, ethical, and moral issues that deal with factory farming specifically. With health not being the primary focus with some vegans, they may tend to eat a lot of processed “vegan” food, and be just as unhealthy as someone on the SAD diet. This is why I don’t like calling myself a vegan. I eat honey, have leather clothing, have recently eaten venison from deer that friends have gotten. Calling myself a vegan only takes away from what the word really means.

            Your post reminded me of this cartoon:

          • oh crimmony! what a great ‘toon…I’m mass distributing asap.

            Remember the catch-phrase Ïts the economy, stupid.” Well, I’d leave out the “stupid” because people are brainwashed, but I would love to drill everyone with Ïts the Nutrition”! Leave the belief systems out of it. The science is about nutrition and that is what we ALL should be adopting as the common denominator …. he said, preaching to the choir :)

          • Neil

            Yeah. I love that ‘toon. You should read Michael Moss’s book, “Salt, Sugar, Fat: How the Food Giants Hooked Us”. Incredible. Pulls the curtain back on how the food industry, as you say, brainwashes us.


            Yes, nutrition should be the common denominator. Health costs, environmental issues (less factory farmed animals) and other issues would fall in place if people adopted a mostly whole food plant-based diet. But people on this site are the “choir”!! Which is why I try to get people on this site and watching documentaries about nutrition and where their food comes from. Chipping away one person at a time…

      • Neil

        Coacervate, here is my response to Olaf, but it actually addresses your question, too, so I’m replying to you.

        Hey, Olaf. Anecdotal evidence aside, it seems, according to this study, that the belief of an optimum after-workout window in which to digest protein is an urban, or rather gym, myth:

        What Coacervate may have been getting at is that we can get all the amino acids we require, and can use, through eating whole plant foods. If we exercise more, we burn more calories, requiring us to eat more. If we eat more whole plant foods as a calorie source, we naturally consume more amino acids (aka proteins).

        Here is a very in-depth article on protein requirements from the World Health Organization,
        It states:

        “A more active person expends greater amounts of energy, consumes greater amounts of food, and hence has a higher absolute level of protein consumption.” p.12

        And, as this study out of MIT shows, it is a myth that we cannot easily get our protein requirements from plants. It is also a myth that we need to mix protein sources at the same meal. Our body stores, intracellularly, amino acids that our bodies do not make. So when we eat foods with these limiting amino acids, like lysine, our body stores them, and uses them as needed. See page 1209S, last full paragraph here:

        The other critical misconception is that we, as a society, see nutrition as compartmentalized: proteins, carbs, minerals, etc. We don’t realize how that there are thousands of chemicals and hormones and micro and phytonutrients at play in ways we may never understand. Muscle formation, in other words, depends on so much more than just taking in more protein because there is so much involved on making muscle tissue. Here is one more quote from the WHO study:

        “The pathways of amino acid metabolism and interchange are critically dependent on adequate micronutrient status, and hence upon the amount and quality of food consumed. *** In addition, with either supplementation or food fortification, disposal of any excess consumption of micronutrients can impose . . . stress on the body.” See page 12.

        In other words, pounding our body with supplements (like protein isolate in any form) in excess of what we need only makes our body work harder to get rid of the excess. This doesn’t happen if we just get our calories (and hence amino acid requirements) from whole plant foods.

        Point being that supplementing your diet with more protein is not needed. But since it is plant protein, there is no harm, whereas doing the same with animal protein (whey, dairy, meats, etc.) does have harmful effects.

  • Ginger C

    Thanks for another video to keep me plugging along at this.

  • Kitsy Hahn

    “But the vegan group didn’t just eat less animal protein, they ate fewer calories.”

    That sentence reads like they did eat “some” animal protein. Not so, though, right Dr. G?

    • Mike Quinoa

      They did eat “less” animal protein than the other group to the tune of zero (or they wouldn’t be vegans).

      • Kitsy Hahn

        Yes, that’s the point I was trying to make. A female can’t be “less” pregnant, say, than Suzy. Either she IS pregnant or she AIN’T. Same with vegans They don’t touch animal products, so IMO the sentence came off as awkward. “Less” should not have been used.

  • Bristol4

    You should make a video explaining how statistics work, in layman’s terms. I’m curious about the exact meaning of “metastudy,” for example.

  • Moonrisin

    Igf 1 seems to be of benefit to older people.

    • Mike Quinoa

      If this is true, a vegan could consume more isolated soy protein to increase his/her IGF-1 levels.

  • cindy

    I’ve gained weight since going vegan. I wasn’t overweight before but now i’m about 10 pounds overweight. Help! any ideas? I really want to stay on a plant based diet but this is frustrating.

    • Johanna

      Check your fat intake as well as how much of your food is processed. Chronometer is a good place to keep a diary. Also, you might be gaining water weight, as plant foods, more simply carbs, require water molecules to travel to your cells. Make sure you get enough water so that you don’t become bloated. My 2 cents.

    • unf13

      I’m experiencing analogous problems. I have noticed that eating cooked foods make my abdominal fat grow especially if i try to get some muscle mass on. Trying to get enough plant protein I eat a lot of whole grains and legumes. But they are very rich in carbs. Ol of them contain more carbs than protein.
      I’ve also noticed that I’m gettin skinner when eatin more raw foods.

    • Thea

      cindy: Most people lose weight when they go vegan. A small, but noticeably “lucky” few gain instead. I can understand your frustration. Usually the weight gain is easy enough to fix if you tweak your diet using the basic principles discussed in these talks:

      1) Free lecture available on line by Dr. Lisle.
      “How To Lose Weight Without Losing Your Mind”

      2) Try Jeff Novick’s DVD, Calorie Density; Eat More, Weigh Less and Live Longer. Also check out Jeff’s DVDs in the Fast Food series. Great, affordable food that is easy to make. All of these are available on Amazon. Here is the first one:
      There are some good resources/cookbooks that give more detailed guidance on putting the above ideas into action. So, after you watch one or both of the above lectures, you might take a look at:
      > The Starch Solution (Dr. McDougall)
      > Breaking The Food Seduction (Dr. Barnard)
      > Consider going through the free 21 Day Kickstart program by PCRM. They will hold your hand for 21 days, including meal plans, recipes, videos, inspirational messages, and a forum where you can ask questions.
      (Click the green “Register Now” button.)

      Hope that helps.

  • Luke

    So how would athletes perform / build strength if they limit igf1? Sounds like you can either have close to 0 risk and be learn, small and have the body run in a maintenance mode do to speak but to build strength size or have increased ability your risk rises…

  • Ronald M. Chavin

    Unfortunately, the connection between IGF-1 and cancer is not as simple as Dr. Greger would have us believe. For example, the older we get, the MUCH HIGHER our risk of developing cancer but the MUCH LOWER our blood levels of IGF-1. Also, a person who needs to increase their bone density and muscle strength would greatly benefit from eating extremely healthy foods such as natto, tofu, edamame, unsweetened soymilk, soy yogurt, soy sprouts, fenugreek seeds, wheat germ, and/or wild ocean fish, all of which are high in the amino acid, methionine, and therefore will successfully raise our blood levels of IGF-1, thereby increasing our bone density and muscle strength.

    Meanwhile, here’s an interesting scientific study that links LOW blood levels of IGF-1 with INCREASED risk of developing aging-related diseases and SHORTER lifespans in real human beings. Strangely enough, when this same experiment was done with worms, flies, or mice, researchers got the exact opposite result:

    • unf13

      I wonder if there is any statistics about the longevity and general health of meat eating bodybuilders since they apparently should have relatively high blood levels of IGF-1 due to constant consumtion of animal proteins either from foods and protein supplements. I personally know a couple of amateur bodybuilders in their 50 who seem to be quite healthy and vital.

    • largelytrue

      This study in mice suggests a possible causal link between reduced IGF-1 with aging and decreased survival. Specifically, the authors suggest that it’s a combined relationship, with high GH in the face of low IGF-1 being what is driving the extra mortality in these mice.

    • bob

      There is also this:

      “Research suggests that as people age, their ability to absorb or process protein may decline. To compensate for this loss, protein requirements may increase with age. Megumi Tsubota-Utsugi, PhD, MPH, RD, of the National Institute of Health and Nutrition in Japan, and her colleagues in Tohoku University and Teikyo University, Japan, wondered whether protein intake might affect the functional capabilities of older adults. They designed a study to investigate the relationship between protein intake and future decline in higher-level functional capacity in older community-dwelling adults in Japan. Their analysis included 1,007 individuals with an average age of 67.4 years who completed food questionnaires at the start of the study and seven years later. Participants were divided into four groups (quartiles) according to their intake levels of total, animal, and plant protein. Tests of higher-level functional capacity included social and intellectual aspects as well as measures related to activities of daily living.

      Men in the highest quartile of animal protein intake had a 39 percent decreased chance of experiencing higher-level functional decline than those in the lowest quartile. These associations were not seen in women. No consistent association was observed between plant protein intake and future higher-level functional decline in either sex.”

      My impression is that up to age 65 or so…being a vegan pays off in reduction in cancer…after 65 see the above?

      Also this:

      l-Arginine: anti-aging pilot study

      “In an open-label randomised limited study conducted by the author, 5 g/day l-arginine base was administered orally once at night for 28 days in 21 subjects with age ranging between 41 and 75 years old (14 between 41 and 49 years, 4 between 50 and 59 years, 2 between 60 and 69 years, and 1 between 70 and 79 years), 16 were males and 5 females, 17 were non-smokers and 4 smokers, and 18 of the 21 subjects were taking other medications to control either hypertension, myocardial ischemia, diabetes, gastro-oesophageal reflux disease (GERD) and hyperacidity, hypothyroidism, neuritis, or rheumatoid. All recruited subjects gave written informed consent that complied with the principles of the Helsinki declaration.”

      The cohort of people over 65 is increasing daily…yet there’s not a lot of research related to healthy aging? Younger people are going to be so distracted by trying to survive the effects of resource depletion and global warming that they won’t need to worry? Please…do not harm the messenger.

  • Jordan

    What about this?

    “Our study shows how calorie restriction practically arrests gene expression levels involved in the aging phenotype — how some genes determine the behavior of mice, people, and other mammals as they get old,” says senior study investigator and NYU Langone neuroscientist, Stephen D. Ginsberg, PhD. Ginsberg cautions that the study does not mean calorie restriction is the “fountain of youth,” but that it does “add evidence for the role of diet in delaying the effects of aging and age-related disease.”

  • Suzir

    Thank You. Always great info

  • Youcef

    Hi everyone. Thanks Michael Greger M.D. for this video. Very interesting :)
    I am just struggling to understand why you presented the last frame, which I find rather misleading (from “These findings” to “interventions”).

    The conclusion on rodents/humans seems invalid, unless the studies on rodents compared CR and non-CR using a western diet both with animal protein. More importantly, when it comes to the benefit of protein reduction, this cannot be concluded without the important protein distinction (animal vs. plant), which we know to impact IGF-1 metrics. Also, quid of soya consumption?

    New question: Why is there such a focus on the IGF-1 by-product instead of the GH that it came from?

  • Larry Taylor

    Dr Gregor. I have a related question. I am a 100% high carb vegan. Presumably i have lower serum IGF-1 levels than the meat & dairy eating population. If i switch from endurance exercise to weight training am i likely to weaken that advantage?

  • Lucia Redondo Cuevas

    May be not all the proteins have the same effect in IGF-1 levels… There are some papers about the differences of the effect of meat protein and milk proteins and it seems that only milk proteins have this effect…

  • gursharan singh

    hello Dr i am suffering from diabetic nephropathy with creatinine 2.2 plz suggest me what should i eat and how much

  • David Fell

    Does the link between “reduced protein intake” and decreases IGF-1 apply any protein or just animal protein?

  • Derrek

    What diet do you follow and why? 80/10/10? And any research?

  • Is the source of protein relevant here for IGF-1 in terms of animal or plant-based? I currently supplement with several scoops of vegan plant-based protein powder each day. Should I be concerned about cutting this to a certain level or is this only relevant to a certain type of protein? thanks.

  • Pedro Sousa

    Well, this still ends with a big maybe.

  • PRO

    This guy is extremely knowledgeable but why does he speak like he has marbles in his mouth?
    The facts are great but it’s difficult to listen to him for longer than 30 seconds.

  • Michael

    At the end of the video, the Dr. says something to the effect of people with high protein intakes generally have a higher IGF-1 levels. Does this include plant based protein sources? I can’t imagine the doc saying that protein from beans, for example, are just as unhealthy as protein from an animal source.

    Thanks for all your efforts and information

  • unf13

    It’s very controversial. What about this study?
    “A study from Tulane University published this year (2014) showing that people who went on a low-carbohydrate diet lost more weight in one year than did those in a group who followed a low-fat diet for the same amount of time. More importantly, the study showed that the people on the low-carbohydrate diet ended up with fewer cardiovascular risk factors. ”

    • NFc

      Here’s the study being referenced

      First thing to point out is “lost more weight” and “ended up with fewer cardiovascular risk factors” tend to mean the same thing in these short term studies. Losing weight alone improves bloodwork, so the way this and many other trials like it are designed, it’s simply whichever group loses the most weight will look the best on paper.

      Second thing to point out is that 30% of calories coming from fat isn’t “low fat,” and the 15 grams of fiber a day (the same as the low carb group, even though fiber itself is a type of carb) points to refined carbs in the low fat group rather than whole foods that are associated with lowering cholesterol and blood pressure. These studies aren’t very useful for determining what we should eat since they basically just put people on the standard American diet and another group on a slightly less bad diet and then see who loses more weight. It doesn’t mean you should eat less carbs and more fat, it means if your diet is already terrible, reducing the amount of refined carbs you eat (and the calories you consume) will give slight health improvements that may ultimately do nothing for you.

  • Tal

    I have a question for Dr. Greger
    What is your recommendation regarding how many calories one should consume? Of course when on a plant based diet.
    Thank you

    • Toxins

      Tal, as long as you consume whole, unprocessed plant foods, calorie needs will be dictated by hunger needs. Eat when you are hungry, till you are full. Counting calories is not necessary.

      • Tal

        Thank you very much :)

    • Thea

      Tal: Just to underscore/support what Toxins just wrote to you, here are Dr. Greger’s overall nutrition recommendations.

      Note how the recommendations do *not* specify a calorie count. That’s because, *if* you eat the right foods, you naturally consume the correct number of calories for your needs. That instinctual ability is built into all animals. Dr. Lisle does a great job of explaining this concept in the following entertaining lecture (which was a great eye opener for me when I first heard it!):

      “How To Lose Weight Without Losing Your Mind”

      If you get a chance to watch the above video, I would be curious to hear if you feel that it answers your question to your satisfaction.

  • Nia Veg

    can’t get anyone to answer me regarding the latest diet war on youtube,
    perhaps the NF team can?! The big claim is adult women can eat 1600
    calories per day (and even lower, I have seen people doing 800-1000) with lots of exercise, and this is a healthy weight
    loss plan. I wonder if this is true, because online calculators put me
    at needing 2400 a day to walk my dog, and I am a 31 year old woman who
    is 5’8″, 115 lbs, and have always had a bmi of only 18 which I think
    classifies me as one of those “naturally tiny people”. I do not
    understand how it could be healthy to eat less than what is needed to
    sustain a tiny body like mine. Can you guys help me understand this?

    • Joseph Gonzales R.D.

      Hi Nia. Calorie needs are vague and confusing. There are many ways to calculate energy needs using a plethora of equations that take into account age, activity level, disease states, etc. I cannot crunch your individual numbers, but I might add it may not be necessary. Here is the DRI for energy intake, if interested. Here is more information that may help: In this study, A multicenter randomized controlled trial of a plant-based nutrition program to reduce body weight and cardiovascular risk in the corporate setting: the GEICO study participants followed a plant-based diet with no portion control and still found significant weight loss. A few more videos on calorie restriction and diet from Dr. Greger if interested. And here. Let me know if this helps? I tend to avoid youtube wars :) as there are so many different approaches to diet and health it’s hard to know who is “wrong” or “right”. That’s why we have the research here free and available so everyone can make up their own mind.

      Thanks for your questions,

  • Courtney

    How many calories should a person eat? I feel a lot of people (plant based and not plant based) argue on what really is calorie restriction and what is considered over eating therefore gaining weight.

    • Joseph Gonzales R.D.

      Hi Courtney. I touched on this below. Please see my comments and let me know if they’re helpful? The short answer is am not sure what the perfect amount of daily calories, especially because what we eat varies daily and we’re all different. Most of the studies I have been a part of discouraged calorie counting and portion control. I cited that study below. See if it helps.


  • KS

    Unfortunately this video represents the CR community in a bad light. As a result of that study (from way back in 2008) many people following a caloric restriction diet reduced their protein intake to the levels recommended by Dr. Fontana. To verify that the changes had an effect, most CR followers now test for IGF-1 levels and adjust their protein intake accordingly. Just like the followers, CR people follow the science. When the science changes our understanding, most of the people follow. I started CR in 2009 and have never followed the high protein version of CR. It’s working well for me.

  • Baylen Miller

    Dr. Greger appears to recommend daily intake of nutrients. What about people who fast for 20+ days and blood work looks good? It would appear daily nutrition is not vital. What is the first nutrient your body begins to need in an extended fast? Thank you Dr. Greger & team for your dedicated service — I can’t thank you all enough.

    • Thea

      Baylen Miller: I just had the privileged of hearing Dr. Klaper speak. Dr. Klaper is from the True North Center, a place that helps people reverse serious medical conditions through extended fasting, such as 20+ days like you mention. But Dr. Klaper tells his patients that the fasting is the teeny tiniest of blips in their journey to health. What matters is the food that is eaten afterwards. Dr. Klaper recommends a whole plant food diet just like Dr. Greger. In other words, being healthy is not about fasting being good and then only certain nutrients coming into play. Being healthy is about eating whole plant foods in order to get all of the nutrients you need whenever you decide it is time to eat.
      Or put another way: Long term, intermittent fasting can be healthy, but in the end, we all have to eat. And to be healthy, that food we eat should mostly be whole, minimally processed plant foods. That’s how you make sure you get the nutrients you need.

      • Baylen Miller

        Thank you for that response, it was informative and I agree. I struggle with overeating often (WFPB foods) and I wonder if, compared to a person who eats less, I am taxing and aging my digestive system more than is optimal. But IF helps me not overeat so I am sticking with that for now. I also wonder if a prolonged fast every now and then is good rest for one’s digestive system, helpful in cleaning out existing food matter, and letting the body heal itself (as woo-woo as that sounds).

        Ray Cronise has published research on his “metabolic winter hypothesis” that discusses a possible evolutionary adaptation to a scarce & restful winter. And in our society, of course, “winter” never comes. Not sure about it but interesting food for thought.

        • Thea

          Baylen: I used to consider the idea of prolonged fasting to be pretty woo woo myself But the more I learn about it, the more I think there might be something to it. Or at least intermittent fasting. Thanks for your thoughts/reply. Nice post.

  • Scott

    So what about planties who also regularly fast?
    Are there extra benefits to both eating a WFPB diet and intermittent fasting?