Is Eating Too Much Protein Bad For You? The Not-So-Bitter Truth

A picture of Too Much ProteinOne myth that seems hard to break is that eating a lot of protein is somehow bad for you.

It seems that our evolutionary heritage as meat eaters doesn’t matter, or the fact that our bodies are made with protein.

Why would evolution make us intolerant to something we’ve eaten for millions of years, and that our bodies are designed from?

Doesn’t make a lot of sense when you look at it that way, but this myth is still there, even touted by various professionals.

Let’s see if it’s true, or it’s just another myth of modern nutrition.

Is Eating Too Much Protein Bad For You?

There are two “concerns” that are prevalent about a high protein intake.

The first one, is that too much protein could be bad for the kidneys. The second one is that protein can lead to calcium loss from the bones, ultimately ending in osteoporosis.

Let’s see what the actual evidence has to say.


Do you know what the function of the kidneys is?

They “filter” the blood, removing toxins, electrolytes, fluid and various substances that the body doesn’t need anymore. When the filtered fluid that runs through the kidneys reaches the end, it is called urine.

The kidneys excrete the waste products of protein breakdown. Therefore, some like to argue that more protein adds more “stress” to the kidneys.

Here’s a newsflash: The kidney’s are always under stress. About 20% of the blood pumped by the heart goes directly to the kidneys, and they filter about 180L of blood every single day.

Adding a bit more protein to your diet might increase the workload of the kidneys, but it’s an incredibly small effect given the mind-blowing amount of work the kidneys carry out each day.

Really, this is what the kidneys are designed to do. And they’re damn good at it.

Well, enough with the ramblings. Let’s take a look at the evidence.

This large review article, published in 2004, looked at high-protein weight loss diets and discovered that there is no evidence to assume that there are any adverse effects of a high protein intake in healthy individuals (1).

They also note that bodybuilders, who have a much higher protein intake than the general population, tend to have healthy kidneys.

Another review article published in 2005, examining protein intake in healthy individuals, discovered that there is no evidence to assume that a high protein intake is detrimental to kidney health (2).

The two main risk factors for kidney disease are diabetes and elevated blood pressure.

The funny thing here is that higher protein diets actually improve blood sugar control in type II diabetes (3, 4, 5) and reduce blood pressure (6, 7, 8), suggesting that a high protein diet should actually be protective against kidney disease.

If you already have kidney disease, then you may have a problem with protein and should talk to your doctor.

If you’re a generally healthy person then there doesn’t seem to be any reason to reduce protein, at least not for the sake of kidney health.


Another common belief is that a high protein intake acidifies your blood and “leeches” calcium from the bones.

It is true that some short-term studies have found that increased protein increases calcium excretion, but the fact remains that long-term studies show that a high protein intake actually leads to improved bone health.

The truth is, that a high protein intake shows a positive association with bone mass and bone density. The advice to restrict protein in order to protect your bones may be dangerous and actually have the exact opposite effect (9).

A study discovered that a low protein intake was associated with bone loss and fractures in elderly adults and there were no adverse effects noted in the individuals with the highest protein intake (10).

A large prospective study of postmenopausal women discovered that increased animal protein intake was associated with a lower risk of hip fracture (11).

Multiple other studies and papers show that a higher protein intake is associated with improved bone health and decreased risk of fracture (12, 13, 14, 15).

The Functions of Dietary Protein

The body is in a constant state of flux. Most of our tissues are repeatedly broken down and rebuilt, every second of every day. This also applies to tissues like bone and muscle, and the protein in the diet is used to rebuild these tissues and sometimes to make even more of them (when gaining muscle, for example).

This also applies to organs, enzymes, hormones, receptors and various biomolecules that are made from protein. In order to replenish them, we need enough protein in the diet.

If you’re eating a low-carb diet, part of the protein you take in will be used to generate glucose for the tissues that need it (mainly the brain and red blood cells). Therefore, protein requirement may go up as carbs go down.

A High(er) Protein Intake is a Good Thing

Okay, now we know that the scare tactics against a high protein intake aren’t warranted, at least not when it comes to kidney and bone health.

What about other things? What about general health, body weight, etc?

Higher protein diets have a favourable effect on weight loss, leading to improved body composition and improved biomarkers of disease, most likely mediated by increased satiety and slightly elevated energy expenditure (16, 17, 18, 19, 20).

All in all, the evidence seems to suggest that a high protein intake is beneficial to humans, without any adverse effects despite the scare tactics.

Nothing to Worry About on a Real Food Based Diet

This seems to be another one of those cases where we would do best by listening to the conventional wisdom advice, then do the exact opposite.

If you eat a low-carb, real-food based diet with plenty of animal products then your diet will naturally be high in quality protein.

However, I don’t see any reason to supplement your diet with additional protein or amino acids, except maybe a bit of whey protein after a workout.

There is no reason to eat more than 30-40% of calories as protein, the rest should be from fat (and some carbs).

If you go for the fattier cuts of meat (like our ancestors would do), eat some eggs and butter then your protein levels are going to be within safe and healthy ranges.

If you don’t have any medical problem, then I can’t see any reason not to embrace your higher protein diet, knowing that it is probably good for you despite the scare tactics by the pseudo-scientists.

Your bones will thank you, your body weight will improve, you will be less hungry and given that high protein reduces diabetes and blood pressure then your kidneys may even thank you as well.


  1. ProudDaddy says:

    The only downside to high protein consumption in people without kidney disease that I have discovered is some weak observational studies associating high protein with reduced life expectancy. For a 71-year-old with a bit of belly fat, high protein with strength training is a no-brainer. I KNOW my longevity will be significantly reduced if I fall down and break a hip. (But maybe I’ll try to limit processed meats, just in case.)

  2. Always a great read, what are your thoughts on body building protein supplementation?

    • I can’t really speak for professional bodybuilders. If they feel that they need a lot of protein to grow then I’m sure it’s based on sound experience.

      For the average person who likes going to the gym and sport a little muscle, then I definitely don’t think it is necessary. Eating some animals every day should do.

      It might help slightly to take some protein before and/or after the workout. I do recommend Creatine Monohydrate though. Definitely my favourite supplement to improve performance in the gym, as well as muscle gain.

  3. Vivienne says:

    Hi Kris,

    I agree completely with your ethos of low carb high protein / fat lifestyle choice.
    Four years ago I weighed over 20stone, I decided to make some changes to my life after my father passed away and so joined a gym and changed my eating habits to pretty much everything you have said, within 9 months I had lost 9 stone, I didn’t starve myself, but in truth it did take my body about two weeks to get in line with my new lifestyle, once that happened it was so easy to make the right choices.
    About three months ago I decided to take up a White Collar Boxing Challenge for charity,and was advised to increase my carb intake for the intense training sessions….even with the intense training I still.managed to put on 1 stone, and I know this is totally from reintroduction of increased carbs, needless to say boxing over and I am back on lifestyle choices that changed my life!

    Keep up the great informative work you do.



  4. I love that ProudDaddy! LOL! I had to read it twice!

  5. Kris..good post. I have to agree with having adequate protein intake for the body in the form of animal products. What I have a hard time with is, the intake of protein from whey and other powder sources. Most of the whey is cheap and plentiful and is being touted as what’s needed to build muscle. I did some research and found that too much whey protein can kill vitamin a stores in the body which are already depleted in most people. I think people get confused and think whey protein and other powdered proteins can substitute for good ol’ animal flesh. Not so…I happen to believe our bodies like things that are natural to it. Thanks for thee post.

  6. Kris, this is a great topic. I typically have to tweak my diet plans based on my training needs. This, I have a feeling, is where a lot of people try to avoid. They want a cookie-cutter diet that will do everything for them. And this just isn’t the case. If I’m aiming for muscle growth my protein intake is on the higher end than if I’m working on fat loss. Since everyone has different dietary needs. The average person trying to get fit won’t need the same amount of protein as a bodybuilder. But, as you pointed out, we shouldn’t be afraid to eat what we’re designed to eat.


  7. Kris,

    Great post. I’m sure the average person is getting not enough protein in their diet, rather than too much, and would probably be better off replacing the processed carbs in their diet with real food protein sources.


  8. Prateek says:

    You kind of make me optimistic! I can now freely think of meat, eggs and fish! :)

  9. I 100% agree with you. Did our ancestors decide to cut back on meat some days because they were worried about protein? Absolutely not. If you’re eating a healthy, low carb diet then having a lot of protein is normal.

  10. Haukur Palmason says:

    Great post Kris. In my experience high protein/low carbs diet also makes me more active and less sleepy during the day. Are you aware of any research confirming this, or am I imagining things?

    • Kristjan says:

      I haven’t seen it in the data but I agree with you. I also feel more active and less sleepy during the day and a lot of people seem to have the same experience.

      I can imagine it having something to do with more stable blood sugar levels, also the possibility that this sort of diet may lead to altered noradrenaline activity.

      Edit: Whoops. It is there in the data of one of the controlled low-carb trials.

      If you check out “Figure 1″ you will see that fatigue scores are lower in the Low-Carb group. Hunger scores are also much lower, despite the Low-Carb group losing twice the amount of weight compared to the Low-Fat group (-12,9kg vs. -6,7kg) over a period of 6 months.

  11. Heya Kris, good stuff man. :-)

    While I don’t see a need for very high protein intake even for those that train hard (so a somewhat higher intake is justified here), I can only totally agree that protein is not the culprit.
    Stephen Byrnes, PhD, RNCP, for instance, confirms it:
    “It is excessive carbohydrate intake, not protein or animal protein intake, that can result in heart disease and cancer.”

    Talk soon,

    Mark Kislich, Olympic Performance Coach

  12. The danger here is not the protein is that fat got the usual sugar coated treatment.

    Eat LOTS of protein but without adequate fat and you will be sick, FAST. Period.

    A high protein diet in the asbence of the majority of calories from fat or carbs is indeed not healthy. My ancestors had a name for it, “Rabbit fever”, the result of spring hunts yielding only small animals like rabbit with no fat stores. This diet could take a strong brave and turn him into a wreck in a matter of a week.

    When the casual reader sees a headline like this and reads the article with only passing mention that anything more than 30 to 40 percent is useless (far from useless, from there it gets dangerous). They could well be encouraged to continue their dogma designed diet of low carb, lean protein, fear of fat.

    I think perhaps more stress on the fact we should not eat so much protein as to cause the body to switch to it for a primary energy source. Amonia in the liver and urine causes all kinds of issues. My native elders, my inuit brothers, all knew this. It is never glossed over, but simply stated, “eat the fat first”.

    An article like this, in my mind, should have included the possible end point. A mostly protein diet in the absence of sufficient fat or carb. You may well have had a more responsible headline.

    • I don’t see a problem with the headline. It doesn’t really give anyone an answer without reading the article, simply implying that the truth may not be as bad as they might think.

      “If you eat a low-carb, real-food based diet with plenty of animal products [usually high in fat] then your diet will naturally be high in quality protein.

      However, I don’t see any reason to supplement your diet with additional protein or amino acids, except maybe a bit of whey protein after a workout.

      There is no reason to eat more than 30-40% of calories as protein, the rest should be from fat (and some carbs).

      If you go for the fattier cuts of meat (like our ancestors would do), eat some eggs and butter then your protein levels are going to be within safe and healthy ranges.”

      My readers know very well that I encourage a relatively high-fat diet.

      Do you know of any cases where western dieters have suffered rabbit fever from avoiding both carbs and fat (not that this article is even remotely suggesting that)?

  13. Hey Kris!

    I started a low-carb diet about a month ago to restart my weight loss. I was keeping carb intake at about 60g or lower, sometimes as low as 45g. For two weeks I bounced around from feeling great to not so great. A lot of dizziness and feeling like I was going to black out. The days I felt better was when I included some form of whole grain carbs or extra fruit as a carb. Then I went to visit family in Hawai’i for two weeks & there was NO low carbing there! And, of course, I gained a couple pounds. So my intention is to go back to low carb eating and getting back into my routine & trying to lose weight for my son’s wedding in a month. Any suggestions on getting started again? An additional note…it took a week of adding carbs before the dizziness and black out feeling stopped. I don’t believe I “overloaded” on carbs as we ate a lot of protein rich meats/fish and rice but I definitely went over 100g. I’m 44 years old and had lost 36 pounds via the low-cal/exercise-like-mad route and now I’ve gained 10 lbs. back. I workout 3-5 times a week, various routines with weight and cardio and cross training. I feel I need to lose at least another 40-50 lbs but obviously not in a month’s time. I’d be happy to lose the 10 I’ve gained for starters.

    • Kristjan says:

      Hello Shawni. If you didn’t feel too great going very low on the carbs then maybe try not to go under 100g per day. Try throwing in a couple fruits to up your intake a little bit.

  14. I had this problem of feeling dizzy and like I was going to black out when I first tried low carb dieting. It turned out the problem was not the low amount of carbs but lack of salt.

    When following a low carb diet, your body excretes more salt, also when you cut out processed foods and refined carbs, many of these foods are high in salt, so you are taking less salt in.

    If you don’t add salt back in then you could easily become deficient. Now I add a pinch of salt to all my meals and the dizzy spells, fatigue and weakness have gone.

  15. Good review of the literature, especially the Osteoporosis bit.

    Not sure when you wrote this article but this myth was in the news again recently!

    I find it so infuriating that the british dietetic association will put out such nonsense. So I wrote a quick blog post about it here:

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