Do high protein diets shorten lifespan?

Strong old man high protein diet longevity

I’ve written quite a lot on this blog about why a high protein diet is the most effective way to rapidly lose weight and achieve an optimal body composition. I’ve also written about how it’s been shown to prevent fractures and muscle loss in elderly people.

So it comes as a bit of a fly in the ointment when you hear that “ah yes, it may help you lose weight and improve bone density and muscle mass, but it will also cause you to die sooner.”

The claim that a high protein diet shortens lifespan actually comes from the same people who discovered that protein is the central factor controlling appetite and calorie intake, David Raubenheimer and Stephen Simpson at the University of Sydney.

Unfortunately, there is at present no human experimental evidence that can show whether or not a high protein diet has a life shortening effect, so everyone on either side of this debate is forced to rely on experiments in animals. In particular, on mice. Mice, like humans, are omnivores – they generally eat whatever they can get a hold off, and at a fundamental physiological level, they’re quite similar to us. But they’re small and only live two years, which makes big diet experiments feasible.

A decade or so back, Raubenheimer and Simpson conducted a large experiment on mice, in which the mice were randomised to follow diets with varying proportions of protein over the course of their entire life span. In their book “Eat Like the Animals”, they state that this resulted in a dramatic difference in the longevity of the mice. They use the following graph to prove it:

Yes, it is a bit difficult to understand, I agree. Basically, they’ve converted every individual mouse life span in to pin point and coloured it a shade of grey, with darker representing a longer lifespan and lighter representing a shorter lifespan, and then put that colour at the junction on the graph representing the relative protein and carbohydrate intake for that individual mouse. All clear? Thought so.

When I look at the graph, my spontaneous interpretation is that the mice following a very high carb low protein diet lived a median of 117 weeks, while the mice on a very low carb high protein diet lived a median of 105 weeks. In human terms, that would represent a difference of five or six years between those following the highest protein diet and those following the lowest protein diet for their entire lifespan (two weeks for a lab mouse is roughly equivalent to a year for a human).

However, if you avoid the fancy statistics and just go and look at the overall median lifespans instead (which is intuitively easier to understand and more in line with how studies normally try to determine if there is a difference in longevity between groups), a different picture emerges:

Although the mice that were getting 60% of their macronutrients as protein lived noticeably shorter than the rest, below that extreme level there is no clear pattern. In fact, the mice on the 42% protein diet were the second longest lived, and only lived two weeks shorter than the group that was on the 5% protein diet.

Ok, so the graph is showing the protein to carb ratio, and the table is showing the total intake of each of the three macronutrients, so they’re not showing the exact same thing, but it’s odd that the picture they seem to paint is so divergent. While the graph seems to show that a high protein diet noticeably shortens life, the table suggests that it doesn’t. How do we explain the big apparent difference?

I corresponded with Stephen Simpson a few months back and was able to get an answer which finally made some sense to me. The explanation is offered by looking at another somewhat complicated graph, which was recently published in a review in iScience.

The graph shows average mortality for each age group over the course of the lifespan, with blue meaning lowest, green-yellow meaning in-between, and red meaning highest. What we see is that during the first 2/3 of the normal mouse life span, the mice are least likely to die on a relatively low protein diet, with a 0.3 protein to carb ratio appearing optimal.

During the final 1/3 of the normal life span, things switch over however, and the mice become much less likely to die if they dramatically increase their protein intake, and start to consume 1.3 grams of protein for every gram of carbohydrate.

In other words, while the mice on the high protein diet were more likely to die during their early years, they made up for this by living longer once they reached middle age.

The reason there is no noticeable effect on the overall median life expectancy is that death is uncommon during the first two thirds of the life span, regardless of diet chosen, but common during the final third of the life span. Most deaths happen in the final third of the normal life span regardless of what you do to the mice – just as most humans subsisting entirely on junk food and cigarettes will still live long enough to start collecting a pension. So although the period in life where a low protein diet is optimal for longevity is roughly twice as long as the period where a high protein diet is optimal, there is little difference at the end of the day.

I know we’re just talking about mice here, but in the absence of any good human data, it’s the best we have to work with, and it’s reasonable to think that a similar pattern would be seen in humans. As mentioned earlier, the benefits of a high protein diet in elderly people are indisputable – it prevents loss of muscle and bone mass, which should allow them to not just live, but to live independently, for longer.

So what can we conclude from this?

If you just look at overall averages, then there is no noticeable difference in life expectancy between those following a low protein and a high protein diet. If you dig in to the details however, the most optimal diet to follow for longevity appears to be a relatively low protein diet up to middle age, followed by a relatively high protein diet during the final decades of life. That is true if you’re a mouse, and might be true if you’re a human.

If you are eating a low protein diet though, you need to make sure to get lots of fibre – if you eat a low protein diet without plenty of fibre, you will absolutely get fat. The only way to avoid obesity on a low protein diet is to pare it with a high fibre intake.

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36 thoughts on “Do high protein diets shorten lifespan?”

  1. Good morning,
    Did the mice that were having a lot of carbohydrates in comparison to protein diseases like diabetes, weight problems, dyslipemia, etc. etc. and even so their life spans were better?
    I really think this research cannot apply to humans

  2. I see two flaws in this
    1. A mouse is a mouse, and a human is a human. No differences expected. However, the few mice that survived the first 2/3 of a normal lifespan on a high protein diet are less likely to die during the rest of their time. You do not se, what happens if you change the diet!
    If you offer a mouse fresh greens and fruit, seeds, grains and meat and cheese, the never touch the meat and cheese. They only do that in order to survive when starved.
    2. Carbs are NOT just Carbs. The quality of the carbs and their origin differs a lot, and one may live a long, healthy life and stay slim on a high carb diet!

    1. Same for fats and protein. There are different kinds and we need good quality and diverse combination of proteins and fats.

      The latest Zoe podcast touches on the subject of life expectancy and nutrition. Nothing groundbreaking but may be interesting to listen to for 15 minutes. Unfortunate, they also, sort of, miss the point of the quality and diversity of the food stuff.

  3. The first thing you have to remember, ANYTHING coming out of the mouth of a doctor (present company excepted) is suspect.

    I’ve said it before, and I know it’s only anecdotal, but my experience mirrors your findings.

    After trying to lose weight for almost my entire life (my grandfather and then my uncle owned a bakery and made the most incredible pastries you could EVER eat…no I’m serious I’d stack them up against the best you EVER ate…he used lard, not BS seed oils like they do today), it wasn’t until I went to a high protein eating plan, with intermittent fasting) that I dropped 60+# of BODY FAT. I went from 30+% body fat to LESS than 10%. I went from an obese BMI to normal (if BMI means anything).

    I was vegan, vegetarian, exercised like crazy and could NEVER keep the weight off. It took me over 50 years to realize carbs were the problem.

    I’ve never felt better, especially when I pull out my old clothes which I couldn’t wear because they were too tight.

    I eat meat (don’t listen to the bullshit about “bad cholesterol”), eggs, dairy, raw honey, and berries (strawberries and blueberries) and apples to snack. I drink a lot of water, when I’m not drinking milk.

    I do take supplements but am wondering if I need them anymore.

    Remember, these rat bastards are trying to kill us. Big Food makes us sick, so Big Pharma and their dope pushers … AKA “doctors” … can sell us their snake oil. They want to cull the herd … ever since the days of Malthus. They want to get rid of 6.8 Billion people. They are doing a great job. For heaven’s sale DON’T HELP THEM.

    1. Totally agree with you.
      Have organs as well, and always remember that doctors don’t know anything about health they just sell pills to stop symptoms.

  4. Was there a low carb experiment with mice with varying amounts of fat and protein and if so was the food natural or synthetic processed cr-p?

  5. Thanks Sebastian. I love your work.
    I take the liberty of adding/extending thus: (esp Prof Tim Noakes’ work/books/research/collaborations/etc) seems to offer the best/biggest teachings for diet, based on human results now and solid evolutionary data, rather than mice, theories and associations/correlations masquerading as facts/proof.
    Steve Bennett’s new vast is/aims to be the world’s biggest food/nutrition database, and this will grow, along with the data/real evidence. It looks like it’ll help substantially to create a completely new global health economy 🙂
    At the moment that’s about as far as I can go without getting into quantum and ancient/Eastern/forgotten health and healing, which when we consider optimism, placebo/nocebo, dreams, zeitgeist, love, orgasms, nature, the questionable notions about physics and universe(s), reality, and other phenomena that cannot be measured by ‘western’ science and thinking, all suggests that we are using inadequate tools and methods for approaching the subject.
    We cannot understand infinity using finite means.
    I like the analogy of the Native North American plains Indians who apparently were the tallest civilisation on the planet until about 200 years ago, and basically all they ate was buffalo, and so now have obesity/diabetes rates worse than most or any other ethnicities. They had a completely different relationship with health/life/death/cosmos/etc than we do and can comprehend.
    I also like the work of Kazimierz Dabrowski (theory of – TPD), which aligns in different ways with Frankl, Albert Ellis, Maslow, Tyson Fury, etc., about emotional rebirth after disintegrations, which is significant in people’s personalities and health/longevity, and quantum (immeasurable unknowns and energies).
    Your pattern/correlations of ‘age:diet’ does IMHO ‘map’ with human evidence, although for reasons that are different to many assumptions/confusions. Insulin resistance takes a while to become chronic.
    Some of us are genetically more prone to addiction than others, just as some of us are genetically more carb tolerant than others (although humans are not designed to eat a lot of carbs per se).
    Emotional Intelligence and Multiple Intelligence are factors, rather than conventionally measured ‘intelligence’. See Goleman, Gardner, etc., and Erik Erikson to understand more about maturity and growth.
    Some of the least wise and most fearful people I know are academically hugely ‘qualified’, and quite/very wealthy. Some of the wisest most compassionate people I know have no academic qualifications at all.
    See Nick Duffell’s work on gender, boarding schools, ‘Wounded Leaders’, etc.
    Also it’s impossible to generalise beyond some very simple ‘facts’, because every person is so different, genetically and environmentally, and fluid, and ‘balance is a process not a state’.
    We are each part of a cosmological/quantum flow, beyond measurement.
    Anyway thanks for your work as ever. IMHO you are among the great pioneering questioners of ‘accepted science’.
    Love and best wishes, Alan Chapman (, etc)

  6. Assuming we are meant to be omnivores like mice. What if we were meant to be carnivore. What’s the ph of a mouse stomach compared to a human stomach for instance?

  7. sources and references, it is a serious study on the tails end of the curve.Extrapolation from the table 1/5of the data give 4,this is the uv level I found last week.

  8. Hi Sebastian,
    Thank you for another great article.
    I want to share with you my personal experience.
    I have a great deal of difficulty in loosing fat around the abdomen.
    I am 67 yo and I train in Power Lifting three times/week.
    I am also vegan and I take stimulants to keep under control my ADHD.
    I hate cardio exercise.
    All this is a perfect condition to sabotage any attempt to lose fat. But there must be away of doing it.
    Any suggestion?

  9. Good review. The old doc, the old man
    Larry Banyash, MD, retired

    PS. Learned a few things. But total numbers are small, so a probable bias effect

  10. Earlier this year I tried a low protein diet using recipes from I lost weight quickly without feeling hunger. But my condition dropped rapidly and I started suffering from sports injuries (left and right calf.) After 6 weeks my herpes played up on my lips. This had not happened for 10 years, so I got scared and stopped the diet. Herpes used to play up after multiple days of heavy physical efforts, like a long hikes or heavy sports week. When I stopped I had lost 4kg, but I bounced back to 5kg more than I started with.

  11. Hello,

    I hope you will give your last sentence about fiber more attention in future posts. By fiber I mean “dietary” fiber; that which is fermented in the large intestine and converted by bacteria into short chain saturated fats. (In my opinion) The “ideal” diet is one which contains the necessary amount of protein, the saturated and mono saturated fats that would come along with that amount to protein and the remaining calories made up by dietary fiber. (The short chain saturated fats that bacteria create from fiber seem to be the ideal form of fat). But does not seem possible to meet our remaining caloric needs with dietary fiber due to availability and palatability reasons. I’m not a fan of eating protein much beyond my needs and while I’m not saturated fat adverse, meeting caloric needs with large amounts of mono/saturated fat has some down sides.

    So I would like to read more about dietary fiber. Sources, digestible versus fermentable calories, palatability, advantages as a source of calories versus proteins and mono/saturated long chain fats, etc.

    Thanks for all you do.

    Philip Thackray

  12. So this study of mice should apply to other rodents, such as tree squirrels. Studies indicate that elderly humans can have 1.3 grams of protein per kilogram for people over 70. Now, some same it should be mostly plant based and others advocate animal based. I have powdered egg whites and low fat cheese and occasionally flesh in secret as not to offend some people(they know who they are).

  13. Some vegetarians I know think that by gorging on chickpeas or lentils they can get a “high protein” diet. The problem is that these foods do not have a complete protein – all of the amino acids necessary for anabolic processes. To get a complete protein from lentils, they must be combined with a grain in the ratio of 1:3 by dry weight (approximately). Thus, a vegetarian diet is by definition a high carbohydrate diet.

    I grew up eating rice and lentils for dinner pretty well every day; breakfast was wheat porridge. For a family of 8 including the baby, we also had 3 l of milk/day, a real luxury, and an egg once or twice a week. Now I eat as much meat as I can.

  14. In many countries there are substantial excess deaths, that are not attributed to covid, and these deaths occur among all age groups, including younger people, according to dr John Campbell in a recent video.
    I used Our World in Data, excess mortality: death from all causes, and many countries seem to have 10-20% excess deaths the last few months and some are even higher. Sweden may be an exception, and for most periods (in 2022) it scores lower than other countries. How to explain it – since vaccination levels are high in Sweden as well?
    Campbell’s video: “A sad day”

  15. Sebastian perhaps you’d like to comment on this study published on Jama network called “Analysis of Thromboembolic and Thrombocytopenic Events After the AZD1222, BNT162b2, and MRNA-1273 COVID-19 Vaccines in 3 Nordic Countries”. Are the results alarming? If I understand correctly this is the study that Dr. Peter McCullough have commented on: “7750 People have had intracranial hemorrhage or stroke just in three small Scandinavian countries. Three countries: 7700 disastrous neurologic events within 28 days of receiving the vaccine.”

    1. “there was an increased rate of coronary artery disease following mRNA-1273 vaccination” ” There was an observed increased rate of coagulation disorders following all 3 vaccines” “There was also an observed increased rate of cerebrovascular disease following all 3 vaccines ” ” the ABSOLUTE RISK IS LOW.”
      I expect to get my second Pfizer booster that is against BA 4 and 5 in a copy of weeks since the boosters are only good for less than 6 months. Pfizer’s shots give me a mild fever that lasts for a day and it clears my body of bad bugs and I feel better afterwards. I understand that some get very uncomfortable. Everybody is the captain of their own ship and the master of their destiny, so they get to decide.
      Remember, Covid can be very bad for you, depending upon your genetic make up. I am not a gambler.

      1. And covid vaccines can be even worse for you.

        risk of 370 per million of myocarditis following covid for the unvaccinated

        risk of 580 per million of myocarditis following covid for the vaccinated

        “What is ‘exacerbation’ for 400, Alex?”

  16. Dr. Marc Siegel clarifies messaging ‘issue’ on newly CDC-approved COVID vaccine booster
    September 5, 2022 Fox News contributor and NYU Langone’s Dr. Marc Siegel says he’ll be offering the latest COVID-19 booster shot to ‘elderly, and high-risk’ patients. He says the risks of the booster is worth it for the elderly. He did not say that for the non elderly. Operation Warp Speed POTUS got his booster. “Dec 20, 2021 Former President Donald Trump has revealed that he received a booster shot of the COVID-19 vaccine and encouraged his supporters to embrace the jabs that were developed during his term of office. “

    1. Dr. Donald “Germophobe” Trump got his booster?” Shock!

      And Marc “Pfizer check-casher” Siegel…

      “Dr. Marc Siegel clarifies messaging ‘issue’ on newly CDC-approved COVID vaccine booster
      September 5, 2022 Fox News contributor and NYU Langone’s Dr. Marc Siegel says he’ll be offering the latest COVID-19 booster shot to ‘elderly, and high-risk’ patients. He says the risks of the booster is worth it for the elderly.”

      Any science behind this, or just ignorant opinion? I’m guessing the latter. Elderly and high risk patients typically have incompetent immune systems, so we can’t be sure that they will get any actual protection from covid vaccines.

      1. POTUS agrees with Dr Siegel. Your opinion has been noted . Apparently Joe Biden thinks that the elderly do get benefits from this booster. What is your view on the new flu shot for the elderly that just came out? I have been thinking about getting it.

      2. I wouldn’t get any shots from pharma, if I were you. They keep adding new, inadequately tested ingredients to their shots, messing with doses, etc.

        But at least pharma has to come clean about possible side effects on the info sheet, since flu vaccines aren’t under an EUA.

      1. Good to know your situation.
        Would be most pleased to have your blog posts resume at some point.

      2. I hope you will find the time and energy again to return to your blog, as I greatly appreciate your levelheaded and common sense information on medical research and topics.

        I liked your book as well.

        All the best, stay well.

  17. I do remember a study done on mice which purported to show that a high-fat diet shortened their life span (or maybe gave them CVD, I can’t remember), but then someone pointed out that the particular strain of mice employed had been bred to be sensitive to saturated fat!

    I wonder if the mice in question were bred to be sensitive to a high protein diet?

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