Caloric Restriction vs Plant-based Diets

Image Credit: Heather Hammond / Flickr. This image has been modified.

Caloric Restriction vs. Plant-Based Diets

Hundreds of thousands of deaths in the United States every year are attributed to obesity, now overtaking smoking as perhaps the main preventable cause of illness and premature death. In particular, excess body fatness is an important cause of most cancers, according to a meta-analysis of studies done to date. For some cancers, about half of the cases may be attributable to just being overweight or obese.

What’s the connection, though? Why do individuals who are obese have increased cancer risk? To answer this question, we must consider the biochemical consequences of obesity, like IGF-1; insulin like growth factor one is a cancer-promoting growth hormone associated with a variety of common cancers in adults, as well as children. Kids who got cancer had about four times the levels of IGF-1 circulating in their bloodstream, whereas people growing up with abnormally low levels of IGF-1 don’t seem to get cancer at all.

I’ve talked about this cancer-proofing mutation (See Cancer-Proofing Mutation), the role animal protein intake plays in boosting IGF-1 production from our liver (Protein Intake & IGF-1 Production), which may explain plant-based protection from cancer (The Answer to the Pritikin Puzzle), and how plant-based one has to eat (How Plant-Based to Lower IGF-1?), but our liver is not the only tissue that produces IGF-1; fat cells produce IGF-1 too. That may help explain this “twenty-first century cancer epidemic caused by obesity.”

So, of course, drug companies have come up with a variety of IGF-1 blocking chemo agents, with cute names like figitumamab, but with not-so-cute side effects “such as early fatal toxicities.” So, perhaps better to lower IGF-1 the natural way, by eating a plant-based diet, as vegan women and men have lower IGF-1 levels. Maybe, though, it’s just because they’re so skinny. The only dietary group that comes close to the recommended BMI of 21 to 23 were those eating strictly plant-based diets; so, maybe it’s the weight loss that did it. Maybe we can eat whatever we want as long as we’re skinny.

To put that to the test, we’d have to find a group of people that eat meat, but are still as slim as vegans. And that’s what researchers did – long-distance endurance runners, running an average of 48 miles a week for 21 years were as slim as vegans. If we run 50,000 miles, we too can maintain a BMI of even a raw vegan. So, what did they find?

If we look at blood concentrations of cancer risk factors among the groups of study subjects, we see that only the vegans had significantly lower levels of IGF-1. That makes sense given the role animal protein plays in boosting IGF-1 levels.

But the vegan group didn’t just eat less animal protein, they ate fewer calories. And in rodents at least, caloric restriction alone reduces IGF-1 levels. So, maybe low IGF-1 among vegans isn’t due to their slim figures, but maybe the drop in IGF-1 in vegans is effectively due to their unintentional calorie restriction. So, we have to compare vegans to people practicing severe calorie restriction.

To do this, the researchers recruited vegans from the St. Louis Vegetarian Society, and went to the Calorie Restriction Society to find folks practicing severe caloric restriction. What did they find?

Only the vegan group got a significant drop in IGF-1. These findings demonstrate that, unlike in rodents, long-term severe caloric restriction in humans does not reduce the level of this cancer-promoting hormone. It’s not how many calories we eat, but the protein intake that may be the key determinant of circulating IGF-1 levels in humans; and so, reduced protein intake may become an important component of anti-cancer and anti-aging dietary interventions.

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.

These studies are highlighted in my video Caloric Restriction vs. Plant-based Diets.

More on the caloric consumption and longevity:

What exactly is IGF-1 and what is the relationship to animal protein consumption?:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of DeathMore Than an Apple a DayFrom Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

62 responses to “Caloric Restriction vs. Plant-Based Diets

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      1. Thanks! This website and I’m sure many other sites promoting WFPB is making a difference . I live small town Ontario population 6000 and to day they have a down town farmers market . Three of the vendors are promoting vegan foods and they do have fairly steady customers . This from a area that bills itself the “Heart Of Beef Country” See pic of Big Bruce. Having said that the one vendor set up a BBQ and selling Bangers N Sauerkraut has people lined up down the street. lol I guess that is reality.

        1. Esben, I too live in an Ontario town of 6k with a farmer’s market – Perth. We pride ourselves on our greenness but throw most of it the benefit away on a Rib-fest “pigout each year.

  1. Does the value of the best of two worlds adds up? How about the combination of vegan diet and caloric restriction?
    Personally I feel I’m in my best shape physically and emotionally only when practicing regular intermittent fasting. And munching on vegan food in-between.

    1. No, for the greatest part these effects do not add up.
      At least when it comes to mTor pathway activity decrease caused both by plant-based diet and CR.
      If mTor is suppressed by a plant-based diet then CR will not suppress it any more.
      Besides it is postulated that mTor suppresession caused by CR it is a consequence not of the calorie restriction but protein restriction. So the same thing (ie. protein restriction) happens with plant-based diet.
      Plant-based diet is superior to CR in terms of having more phytonutrients, antioxidants, vitamins, omega-3, etc. which may be difficult to provide with CR.

      1. This is really interesting what you stated here. “The suppression of IGF-1 in caloric restricted individuals was not due to actually restricting calories, but was due to the decrease in protein consumption.” So, the bottom line here is to just focus on a vegan diet. However, one could be eating vegan all day long, but consuming to many calories, and then the result would be weight gain. And, weight gain is usually fat, and those fat cells could produce IGF-1. So, in a round about way, calorie restriction should be a concern.

        1. OK, good point, my bad, but as I understand you did not come across the video in which dr Greger described vegan diet consisting of beer and french fries (and possibly ketchup :-) ).

          So, basically by vegan diet we all here mean whole plant based diet which usually does not provide too many calories. Of course, what I have stated above may be wrong but it’s only meant to point you into a direction where to look, and you are welcome to look for yourself.

          The point is that CR is difficult to adhere to in the long run, there is no clear proof of it’s effectiveness in primates (in simple terms: looks like primates already do have a lower level of metabolism than for example rats in which CR lowers metabolism and thus works like a charm) and people are usually unable to work productively when fasting.

          Beside that whole plant based diet has many many more benefits compared to CR. Too many to describe them here…

      2. I have been a CR vegan since 1993, have participated in the CR Society Web discussions and there has long been a consistent group of vegans in the CR Society. Interestingly, the omnivores practicing CR are well aware of the dangers of meat and dairy thus they typically consume minimal animal foods like egg whites or small amounts of white chicken breasts, nothing like the SAD diet. In fact, when you look at the typical daily list of food eaten (often posted), the CR omnivores are probably getting more servings of veg and berries than the average “salad & veggie burger” vegan. Most of us practice the CRON (Optimal Nutrition) so I would take issue with any difficulty in getting enough “phytonutrients, antioxidants, etc”. Finally, it is my belief that the small number of vegans who primarily eat vegetables, lower calorie fruit, beans, nuts/seeds and smaller amounts of whole grains and only eat fruit for dessert are actually eating a CR diet or quite close to it. I eat about 1800 ca/day and easily meet all nutrient levels, with zinc being between 80 – 100%. Prior to CR I was eating about 2200 ca/day which included thick slices of daily ww bread, daily brown rice and plenty of sugary, fatty vegan desserts.

    1. Hi Johanna, incase it helps I always just read the transcripts on the videos – there’s a button underneath. Generally it all still makes sense without any pictures and is silent!

    2. I really like the blogs too because Dr. Greger often uses them to give great summaries that tie together many different videos/different aspects related to a given topic. I am finding myself more and more giving a link to a blog post rather than a single video when I want to point somebody to an overview of the science on a given topic.

  2. What about people who are vegan and obese? I began my vegan journey in January and lost 40 lbs but have a long way to go and may never get thin. So in the meantime how do these factors apply to obese vegans?

    1. If you follow a whole food plant base diet without oils it’s impossible to be obese. Give it time and you will return to your ideal weigh for sure. If a vegan is fat is generally because he is eating processed foods or drinks or because he is using too much oil. Anyway you’ll have lower IGF-1 levels than a obese meat eater.

    2. If you follow a whole food plant base diet without oils it’s impossible
      to be obese. Give it time and you will return to your ideal weigh for
      sure. If a vegan is fat is generally because he is eating processed
      foods or drinks or because he is using too much oil. Anyway you’ll have
      lower IGF-1 levels than a obese meat eater.

      1. There are whole food plant based diets and there are whole food plant based diets. I remember one story of a person who remained obese despite a whole food plant based diet – but then he was eating 40 oranges a day. And try losing weight by living on avocadoes, nuts, figs, olives, seeds and the like. Even amaranth and quinoa are pretty high in calories.
        Calories and energy density do matter – even on a whole food plant based diet.

        1. Exactly thank you. Even Dr Greger has said in interviews about that he is aware of the law of thermodynamics. The only sort of exception would be nuts.

    3. Simple carbs with too many calories will cause obesity. Being vegan isn’t the primary goal. The primary goal is to stop eating processed foods with simple carbs. Eat raw plants (except for cooked beans and some cruciferous) instead of processed food, meat, or dairy. How do you do that? Start with a green smoothie for lunch or breakfast. Try sprouting buckwheat as a breakfast cereal instead of processed or cooked cereal. Eat a salad with beans for dinner. Within about 30 days, the yeast in your gut will die off considerably, reducing your cravings for simple carbs. If that doesn’t happen and the cravings are intense, then I suggest looking into some form of therapy for food addiction. Unfortunately, we are all emotionally addicted to sugar and other simple carbs. Overcoming our addiction is the hard part, not choosing healthy food. I wish you the best!

    4. no oil plant based style diet endorsed by most of the plant based doctors, will for most people reduce weight . But if you fail to get to an ideal BMI weight , these same doctors will accuse you of being misinformed, accuse you of using oil or eating processed foods . Even seen one doctor calling one person who was failing to lose weight a liar ! Some of these doctors don’t realize how efficient we can become.
      Truth is you can be overweight following to the letter these PB diets. The key is to have 13 hours between your last meal at night and first meal in the morning so 6pm and earliest 7am , most likely you can go to 10 or 11 am. For me that has been the key to losing weight. It’s not all bad news , if you try this there is a huge bonus , food tastes so much better

        1. Just realize that with your plant based you have more protection than a thin person eating normal food. It’ll happen, and you might hit road blocks but you got it done and just tweaks will get you past them

        2. Just make sure you are taking Vitamin B-12 sublingual supplements, and getting plenty of omega 3’s by adding ground up flax seed and chia seeds to your smoothie or your oatmeal.

        3. Think of all the good you are doing to your body eating all of those nutrient rich anti-oxidant vegetables and berries while you are getting there!!

        4. As a fellow cancer survivor I 100% agree (knew I should have had that mole checked out much earlier! Happily my doctor caught the melanoma just before it escaped out of the epidermous when 5 year survival rates drop from nearly 100% to 30%. Don’t ignore that funny looking mole, get it checked!). Never want to go back to the place of fear and uncertainty.

          I think the key is that you have made a fundamental paradigm shift that will yield immediate and substantial benefits to remaining healthy and cancer free. As you lose weight those benefits will perhaps get a little bit bigger, but I would say that the majority of the benefits a plant based diet happens within days of switching. The compounds that actively fight cancer jump, those that actively promote cancer drop precipitously and the many thousands that support your general health wash through every cell in your body in a healing bath.

          There are a number of compounds in plant foods that just hell on wheels with regard to cancer. Some of those include things like lignans in flax seeds and sulforaphane in cruciferous vegetables (broccoli and the like). These compounds look like they actively kill cancer cells without affecting normal cells.

          There is also the fact that a WFPB diet doesn’t include a number of what I call cancer fertilizer foods, foods that stimulate cancer cells to grow. Methionine, an essential amino acid, is critical to the growth of many cancers. You have to consume some methionine, but excess methionine appears to be key to cancer progression. The same is true for leucine, another essential amino acid, that plays a role in stimulating the production of the enzyme TOR, which appears to be a key cell regulator. Animal protein by far is the largest source of these amino acids. The highest sources of methionine and leucine per calorie is fish and chicken!. Eggs and dairy make honorable mention status with regard to leucine. So much for fish and chicken being the healthy alternatives to red meat or getting rid of meat but keeping the eggs and dairy by being vegetarian. Sure you might have slightly lower rates of heart disease by switching to fish, chicken and low fat dairy, but then die prematurely because you were feeding the cancer you didn’t know you had.

          And a plant based diet contains literally thousands of plant compounds that your body uses to help heal and repair from all of the little and not so little insults and injuries we suffer by just being alive. So while not everything we eat has a direct impact on cancer, eating more plants gives our body the resources we need to keep ourselves healthy so we our own systems, especially the immune system, can work to eliminate any cancers that might form. Animal foods do not have these phytonutrients and so when we eat animals we don’t get the nutrients from the whole plants that get kicked off of our plates to make caloric room. And since animal foods are so much more calorically dense than whole plant foods, adding even a little animal foods means that a lot of plant food has to be removed to make room.

          So a plant based diet is helping you right now to stay healthy and cancer free and that will only get better as you continue to lose weight.

      1. esben andersen: You wrote: “no oil plant based style diet endorsed by most of the plant based doctors, will for most people reduce weight” That’s an odd claim to make since almost every participant on this website reports losing weight when they follow a low calorie dense, whole plant food diet. This does not just mean oil-free, but I think you know what I’m talking about. I’m sure there are some people who have a hard time getting to their target weight, but that doesn’t mean that “most people who eat a diet endorsed by most of the plant based doctors” will fail to lose weight. Almost everyone loses weight on those diets.

        1. I think that is what Esben wrote. My paraphrasing of the first sentence = The no-oil plant based style diet will most cases help people lose weight. This is clear from the rest of the post.

          1. Tom Goff: You could be right. I read the statement multiple times and took it in context with the rest of the post. I interpreted the statement the opposite of what you did.
            That said, the heavens know that often enough I have written my own awkward sentences which ended up saying the very opposite of what I meant them to say. If I misinterpreted, then my reply would make no sense. (But to be fair to me, there is at least one other person who interpreted the statement the same way that I did.)

            1. Oh, yeah. I do that myself.

              I must admit though that I couldn’t understand what your and Alan’s objevtion was when I fist read your comments. Funny how people will read the same sentence and come away with completely different understandings of what it meant.

              Ambiguity (or at least a lack of specificity) is a wonderful thing. I have known people buy very large wine glasses because they were told that they should drink no more than one glass of wine per day.

              1. re: “I have known people buy very large wine glasses because they were told that they should drink no more than one glass of wine per day.” Oh, that’s hilarious. You just made me laugh.

            2. Sorry I meant an oil free plant based diet. Yes Thea I agree the majority of people who I have talked to will lose weight and even more importantly feel a lot better. I now know 3 people who are PB and everyone has lost weight , however everyone thought they should have lost more . Myself I lost 20 lb and then that was it until i started intermittent fasting.

      2. Could you show us any proof at all on that first sentence? I have a very hard time with it. I am wondering if you count yourself as most people ??

    5. Denise Passmore: Good for you for starting on this journey. Before addressing your question, I want to first acknowledge that you did something very hard that most people fail to do – you changed your diet for the better. And not only have you changed your diet, but you lost 40 pounds in about 6 months. That’s awesome!
      Now to your question, which is interesting. I know you are getting responses about losing weight, but that is not what you asked. As I see it, your question is: If I eat a vegan diet, how much cancer risk do I have if I’m not yet a healthy weight? What if I never reach a healthy weight even though I seem to be going in the right direction?
      I’m not an expert, but I have some thoughts/speculation for you. What I picked up from the article above is that IGF-1 levels can increase a) through eating animal protein and b) through our fat cells. Thus, just being overweight in and of itself may raise our risk of getting the type of cancer that is sensitive to IGF-1 levels. However, as shown above, when tested various ways, it appears that the biggest factor in controlling our IGF-1 levels is the animal protein. So, while not a guarantee that you will never get cancer, I would think that your diet is helping even if you never reach your weight loss goals. You are controlling your IGF-1 levels as best you can.
      You didn’t ask for weight loss tips and you appear to be doing great all on your own. However, I have some great tips that will help you lose weight in a healthy way (and that don’t require fasting!). If you reach a plateau or if you just want the tips any time/now, let me know. I’m happy to share.

      1. Thank you that was what I was asking and in fact I am a cancer survivor and really don’t want to go down that road again

        1. You’re doing great! Forty pounds weight loss in about 5 months (two pounds a week) is, as I recall, about what the patients of Dr. John McDougall report — and they are on a very restrictive no-oil regimen. Some of his patients took years to lose all their extra weight.

          Regarding cancer and IGF-1 levels, you might look into the work of Dr. Valter Longo:

          Dr. Long is affiliated with a company that markets, through your doctor’s prescription, packaged foods for intermittent fasting to lower IGF-1 levels. He has done research with cancer patients. (ADDING intermittent fasting that to a plant-based diet is something you would have to research.)

          IGF-1 levels can be checked through blood work at your local hospital.

      2. Thea, please share your ideas with us all. I’m struggling to get the fat out, and still need to drop another 10 pounds.

        1. Rebecca Cody: I’m glad you asked! (I can’t share all this info unless someone really wants it. It’s just too big. But I love to share this stuff.) 10 pounds to go is not bad. But I’m all for meeting one’s goals.
          The nice thing about your situation is that you already understand half the battle. I know that you already understand about the importance of a whole plant food diet and know generally how to implement it. That’s half the learning curve and so I’ll skip all that info. The other half of the learning curve is understanding the concept of calorie density and how to apply it to weight loss so that you don’t get hungry and you still get all the nutrients you need.
          Dr. Greger covers calorie density, but not in enough detail in my opinion for someone who wants to apply it for the first time. I believe that Doug Lisle is one of the experts in the Forks Over Knives documentary, and he gives a great ‘calorie density 101’ talk officially called: How To Lose Weight Without Losing Your Mind. I have watched the following talk from Doug Lisle several times and think very highly of it. And it’s free!!! And it’s entertaining!
          As good as Doug Lisle’s talk is, it pretty much just gives you a solid understanding of the concept, but not enough practical information in my opinion. For starting to get the practical information, I recommend a talk from Jeff Novick,Calorie Density: “How to Eat More, Weigh Less, and Live Longer,” which is no longer for sale. Argh! (I mention it just in case you can get your hands on a copy. Happily, there is a very good second best source for that information: an article that Jeff wrote that you can get here:

          Be sure to pay attention to the charts.
          Chef AJ tells people who want to lose weight to eat “left of the red line”, where I believe the red line is on a diagram of hers representing is 600 calories per pound. And “left of the red line” is all the whole plant foods which are below 600 calories per pound. The above article from Jeff Novick gives you a good sense of which foods are “left of the red line” by food category. But if you want to look up the calorie density of specific foods, you can find many foods on the following site: Most foods on that site have the option of choose an ‘ounce’ as a size. Then you can multiply by 16 to get the calories per pound.
          It would be perfectly respectable if you are one of those people who are just not interested in the theory. You just want to dive right in and want straight how-to information. If you would rather not think about any of that (or start with the theory and then move onto this step), I have one more suggestion that Dr. Greger also recommends in his book, How Not To Die. Consider going through the free program from PCRM (Physician’s Committee For Responsible Medicine) called 21 Day Kickstart. The program will “hold your hand” for 21 days, including meal plans, recipes, videos, inspirational messages, and a forum (moderated by a very respected RD) where you can ask questions.

          (Click the green “Register Now” button.)
          At the end of the program, you will have a very good practical knowledge about how to eat with healthy and “low” (normal for most people) calorie density.
          Another recommendation that Dr. Greger and I share is to get Jeff Novick’s Fast Food videos for tasty, affordable, fast and healthy calorie density recipes. Also, on-line and free is a YouTube series of recipes/cooking shows called something like Chef AJ and The Dietician. I know that Chef AJ will not steer you wrong in terms of weight loss and providing accurate nutrition information.
          How’s that for some tips? If you give these ideas a try, please report back and let us know how it went.

        2. The only thing that I would add to Thea’s excellent reply is that PCRM has a page on healthy weight loss which is worth reading. In particular it notes:
          “Nuts, seeds, avocadoes, olives, peanut butter, chocolate (non-dairy), and full-fat soy products such as tofu, tempeh, and soy cheese, come from plant foods, but are too high in fat to be conducive to weight loss. These foods may be used in modest amounts on rare occasions.”

          1. Thank you both, Thea and Tom Goff. I’ve been watching and listening to some of the linked videos from Thea, and find them helpful and entertaining. I especially love Doug Lisle’s humorous talks and Chef AJ’s talk at Dr McDougall’s gathering, “From Fat Vegan to Skinny Bitch” is a poignant story with many good lessons.

            Now, to get serious about getting the fat out of the diet. That has been the hardest part for me. I don’t eat a lot of it, but I do have two avocados in the fridge right now and usually eat a few nuts daily. I could probably add those back in judicious amounts after losing that 10 pounds and having that loss stabilize.

            Nobody ever talks about this, but I’ve been thinking that, since I’ve shrunk about 1.5″ from my glory days of 5’4″ to now only 5’2.5″, I should possibly consider losing even more than 10 pounds. We’ll see how that goes!

            1. Rebecca Cody: Thank you for that lovely feedback. It’s always so gratifying to me when someone actually clicks a link I provide. :-) But it’s even more gratifying to know that I have helped in some way.

              I’m rooting for you!

              1. Thea, I know how it feels, because I have a cousin who is quite receptive to nutrition information, while so many friends and family think I’m some kind of wing nut!

  3. Devils advocate question: IGF levels are not the goal, lower incidence of cancer is the goal. I know one usually leads to the other, but I’m curious to see a study like this that shows cancer incidence in addition to IGF (much longer and expensive, I know). Are there any studies like this? Maybe one has been done with just rats?

    In other words, there is always the possibility that caloric restriction could effect other processes not being tested that could lead to less cancer. Maybe it’s possible that caloric restriction could have higher IGF levels than vegans, but similar cancer incidents to vegans. I don’t that question has been answered yet, am I right?

    1. I Think the problem is how could you measure cancer rates? We don’t have the technology, it would take many many years and still miss slow growing cancers. For things like this you need to turn to the Adventist studies, but even those aren’t as detailed.

      1. Thanks for the article. At any rate, I’d rather eat a bunch of plants than a little of animals. Actually, I’d rather eat a lot of both! But alas, my logic usually wins out over my gluttony. ;-)

    1. The videos Dr. Gregor has recently completed speak to the problem of variability in testing so perhaps testing isn’t the best approach. Certainly we know that obesity negatively affects health on so many levels, focusing on weight loss through a whole food plant based diet might be better.

  4. I suspect that fat vegans see equal benefits. The weight bias among researchers undermines their work in so many ways and directly fuels the prejudice and discrimination that fat people (and larger than average weight people) face in society and also in seeking medical care. I look forward to the day when medicine stops practicing corporeal phrenology. People interested in the benefits of weight-neutral approaches to health can search on the term Health At Every Size. Signed – Marilyn Wann, author of FAT!SO?, longtime fat rights activist

    1. Congratulations on your weight loss ! Not everyone has the same results however. Some lose little to none on a unrestricted WFPB diet, for sure those people are a minority.
      In horses having a complete natural diet , some horses are notorious for getting too heavy and have serious health problems because of it . Horses are ideal to study for they only eat vegetation , are hind gut fermentators and the only animal that sweats like humans. Almost every farm kid who has ever had a pony knows you must restrict feed to those pony breeds , even in the most natural habitat .

  5. Hello, I wonder how the vegan diet-low IGF-1 connection is applied to the obese or overweight vegans. Vegan diet does not mean staying slim by itself, and I met many vegans who are not on a good diet (probably too much sugary drinks, chips, vegan ice cream..) and are unexpectedly overweight/obese.

    1. I agree, a vegan diet is not a panacea. You still have to focus on whole and minimally processed plant foods. One the most pervasive high calorie processed foods in most people’s diets is refined oil. Vegans with a health focus are pretty good about pointing to the negative health effects of sugar, chips and ice cream, but still can get a surprisingly high percentage of their calories from refined oil from cooking and from salad dressings, not to mention vegan butter and vegan mayo. I know I was completely shocked the first time I did a total food log and entered everything I put into my mouth for a week into cronometer.

  6. For vegan plant food nutrition, 10% calories plant protein is just about right. Mother’s milk has about 7% protein for humans who are growing fastest, note that protein is specifically designed for growing human infants.
    “The China Study” by Cornell nutritional biochemist prof. T. Colin Campbell has several studies where more than 10% protein promoted cancer growth for Philippine children to rats on a control study.
    There are ultra marathon runners who eat just plant foods and have set records. No animal food needed.
    We do vegetables, fruits, nuts, whole grains, legumes no portion control needed, just stop when full. I gradually lost 25 pounds and am at correct weight for my build. No “diet” required.

    1. Thanks for your comment April.

      I tried finding data to compare both groups and could find one study on women:

      “Vegan women had a 13% lower mean serum IGF-I concentration than both meat-eaters (P 0.001) and vegetarians (P 0.0006) (…) The differences in mean hormone concentrations between diet groups were similar after additional adjustment for BMI was made, with the exception of IGFBP-1, where BMI reduced some but not all of the difference between the diet groups”.

      Another study, in men, showed that:

      “Vegan men had on average 9% lower IGF-I levels than meat-eaters (P < 0.01) and 8% lower levels than vegetarians (P < 0.01); adjustment for BMI made little difference to these values".

      Hard to answer your question with precision but that's all I could find.

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