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High protein diets, weight & death

On May 8th 2015, The Independent, and a few other newspapers, reported “High-protein diets increase risk of weight gain, study finds”.

The abstract can be found here. Sadly the full article is not on open view, but I’ve got a copy to dissect it for you below.

The PREDIMED study

In this study, the researchers used the PREDIMED (PREvencion con DIeta MEDiterranea) data to look at the association between protein intake and weight and then protein intake and deaths.

I’ve written about this study before. PREDIMED is actually a randomised controlled trial, rather than a population study, as the 7,447 participants were divided into three groups at the start of the study. Two groups were put on a diet called “The Mediterranean Diet”, which was described as follows: “The traditional Mediterranean diet is characterized by a high intake of olive oil, fruit, nuts, vegetables, and cereals; a moderate intake of fish and poultry; a low intake of dairy products, red meat, processed meats, and sweets; and wine in moderation, consumed with meals.” This is not what people actually eat in the Mediterranean. They eat a diet high in: meat, especially red and cured; fish, especially oily; dairy products, especially cheese; eggs; vegetables; and fruits in season. They also eat potatoes and white grains (bread, rice, pasta) and they drink red wine – not sure about the moderation!

The control group was put on a low-fat diet (that was an adverse intervention, not a control, therefore). The other two groups were put on this Fictitious Mediterranean Diet (FMD from now on) and they were also told to avoid soda drinks, bakery goods, spreads, red and processed meat (apart from the red meat, this is excellent advice). The low-fat diet group was told to have at least three servings a day of bread, pasta, potatoes, rice etc – those nicely fattening products that raise triglyceride levels. The FMD groups were told to have oily fish. The low-fat group was told to avoid it. One of the intervention groups was encouraged to add 50g or more of olive oil daily to their FMD and the other FMD group was given 30g of mixed nuts per person per day.

Of the 7,447 people in the study, 57% were women. The women were aged 60 to 80 and the men were aged 55 to 80. The participants had no previous cardiovascular disease at enrollment, but they were deemed “at-risk”, as only people with type 2 diabetes or at least three other “major risk factors” (smoking, obesity, family history of heart disease etc) were included in the study.

This particular study using PREDIMED data

7,216 of the original 7,447 subjects were included in this protein study. 231 people were left out for having extremely high or low energy intake and/or incomplete dietary data. The 7,216 people were placed into five groups in order of average energy from protein intake – low to high. There were 1,443 people in each group (1,444 in the middle group). The lowest protein intake group averaged 83 grams per day and the highest 96.6 grams, so we’re talking a couple of eggs difference between highest and lowest protein intake here, or 50 grams of tuna.

There were some striking differences in the five groups. They were similar for age, BMI and waist circumference, but the highest protein group were healthier for smoking and drinking: 72% of the highest protein group had never smoked vs 47% of the lowest protein group; 1.1% of daily calories came from alcohol for the highest protein group (HPG) vs 4.5% for the lowest protein group (LPG).

However, some other substantial differences were working against the HPG. Prevalence of diabetes was 60% in the HPG vs 37% in the LPG. Family history of cardiovascular disease was 25.1% vs 19.6%. 40% of the HPG were taking oral anti-diabetic drugs vs 24% of the LPG and three times as many of the HPG were taking insulin as the LPG. The HPG also did less activity than the LPG.

The energy intake of the five groups was one of the most striking differences: an average of 1,972 calories per day in the HPG and 2,453 calories per day in the LPG. The substantial difference in calorie intake impacts the percentage of energy from protein intake (the denominator effect for the mathmos). The article thus claims that the lowest calorie intake group was at greater risk of weight gain!

Model 1 in the paper adjusted for age, smoking, exercise, alcohol and similar lifestyles factors (and for the PREDIMED intervention!) Models 2 and 3 further adjusted for health conditions and medications, but they also played around with other macro nutrients (fats and carbs), as we’ll see.

After the baseline differences, the next interesting thing was that the study defined weight change as those who lost or gained ≥ 10% of body weight. That’s a lot in study terms. A weight change of 5% is more typically used as a measure. Everyone else was put in the “maintained weight” category. This high bar meant that, during a median follow-up of 4.8 years, 186 cases of weight loss were recorded and 149 of weight gain. So, the headlines about weight gain are immediately based on 149 people, not 7,447.

Then, of these 149 people who gained weight, 93 were in what was considered a normal protein intake range, 37 had protein intake lower than this and 19 had protein intake higher than this. Now we’re down to the headlines being based on 19 people. (This part of the paper looked at just three groups – low/normal/high – not the original five).

For the raw data facts, 2.1% of the lower protein group gained 10% or more of their starting body weight; 2.1% of the normal protein group gained 10% or more of their starting body weight and 1.9% of the higher protein group gained 10% or more of their starting body weight. The higher protein group thus had a lower incidence of weight gain (fractionally) than the other two groups.

When it came to losing 10% or more body weight, this was achieved by 2.6% of the lower protein group, 2.4% of the normal protein group and 3.5% of the higher protein group.

So the higher protein group had a lower incidence of weight gain and a higher incidence of weight loss. None of these results was statistically significant, but they make a mockery of the media headlines.

The one significant result

When protein intake alone was looked at, using the standard measure of grams of protein per kilogram of body weight (with data unadjusted or fully adjusted), not one significant result could be found for weight gain, or weight loss, or waist circumference increase, or waist circumference decrease. Nothing. Zippo. Zilch.

The researchers should have stopped there. Or reported that protein intake has no impact on weight or waist circumference either way when 7,216 people are followed-up for an average 4.8 years.

But no. They decided to adjust for fat intake, which allowed the claim that the higher protein intake must be at the expense of carbohydrate and they adjusted for carbohydrate intake, which allowed the claim that the higher protein intake must be at the expense of fat. They looked at all protein options possible (total protein intake, animal protein intake, vegetable protein intake, the ratio of animal to vegetable protein intake), for weight loss, weight gain, waist circumference increase, and waist circumference decrease. That’s a total of 128 different options that they looked at. Seven showed a significant difference and only one of these was reported in the abstract:

1) The one statistically significant finding reported in the abstract was that, when protein replaced carbohydrate the hazard ratio was 1.9 with the confidence interval being 1.05-3.46 – 1.05 being so close to the non-significant 1.0. (The confidence intervals are wide because of the very small numbers we’ve ended up with – 19 people).

2) The six statistically significant findings in the body of the article, but not the abstract or headlines, were all related to low intake of vegetable protein. They were that:

i) People with the lowest intake of vegetable protein were less likely to lose weight (in both the carb and fat ‘replacement’ models). The opposite didn’t help – people with higher vegetable protein were not more likely to lose weight.

ii) People with the lowest intake of vegetable protein were less likely to have a reduction in waist circumference. They were also less likely to have an increase in waist circumference. Again – this was the case for both the carb and fat ‘replacement’ models – making four statistically significant, but rather irrelevant and unexplained, results.


I haven’t repeated all of the above for deaths. The hazard ratios for deaths are presented in Table 2 of the paper. Let’s take the raw data again (Note below): There were 69 deaths (among 1,443 people) from any cause during the follow-up in the highest protein group (HPG). There were 95 deaths (among 1,443 people) from any cause during the follow-up in the lowest protein group (LPG).

If we play the association, relative risk game that is usually played, that could be presented as 40% higher deaths in the lowest protein group. The fact is that the absolute death rate in the HPG was 4.8% and it was 6.6% in the LPG. Cardiovascular death rates were 1.0% in the HPG and 1.7% in the LPG. Cancer death rates were 1.9% in the HPG and 2.6% in the LPG.

The researchers noted U-shaped patterns in the data (the middle group tended to be the low point and either side tended to be higher). Instead of comparing low protein intake with high, they compared everything to the middle group and then only reported how bad the high protein intake was. The low protein intake was arguably worse.

(Note – the adjusted models don’t make intuitive sense: smoking & alcohol work in favour of the HPG, but diabetes and meds – especially insulin – work against the HPG. Model 1 adjusts for the lifestyle factors, so I would expect the results for Model 1 to swing against the HPG – and they do. However, Models 2 and 3 further adjust for medical conditions and medications, so I would expect these to swing back in favour of the HPG and they don’t).


The actual study conclusion was “Higher total protein intake, expressed as percentage of energy, was significantly associated with a greater risk of weight gain when protein replaced carbohydrates.”

The headline should have been: “There is not even an association between protein intake, weight gain, weight loss, and/or change in waist size.” The supplementary headline should have been “When we play with numbers to try to get a result, we still can’t find anything in 121/128 cases and the other 7 are nothing to write home about.”

Or: “People with low protein intake are 40% more likely to die.” ;-)


Protein is in all foods except pure fats (oils/lard) and pure carbohydrate (sucrose). Protein is in lettuce, apples, bread, steak – every other food. There is no pure protein food on the planet. Skinless chicken breasts and white fish are the closest we get to being able to eat protein alone. Hence eating more protein in a natural (real food) diet means eating more carbohydrate (beans, pulses, fruits, vegetables, potatoes, oats) or more fat (meat, fish, eggs) or both (dairy products, nuts, seeds). Eating more protein unnaturally would mean removing the skin from chicken – or worse – protein shakes etc.

I do think that an unnaturally high intake of protein is potentially harmful. Protein shakes etc will place unnecessary strain on the kidneys, deplete vitamin A and may have long-term harm. However, unnaturally high protein diets have a metabolic advantage (thermic effect of nutrients) and would be expected to have a positive impact on weight while having a negative impact on health. Death within 4.8 years I would find highly unlikely, unless the protein intake was extreme, which was not the case in this study (83-96.6 grams/day).

That’s a general point – it’s not what this study is about. I’m afraid that this study reinforces a trend that has been taking place for some time – researchers playing with numbers and over-emphasizing any slightly significant finding, while ignoring the truer picture that there was no finding, to grab headlines. The bar for nutritional studies needs to be substantially raised and adhered to.

34 thoughts on “High protein diets, weight & death

    • finally someone with a brain to actually show us the truth, unbiased intelligence rules!!when is this type of knowledge going to trickle down to the people on the ground, it pays to research.

  • I heard that with body building you should eat high protein and high calorie foods, not just protein.

    Protein does have an effect on insulin, but I’d take that over sugar or carbs.

    Whenever I use protein in a shake form, I always take it with fat. In fact, I never eat protein without fat to go along with it.

    Also a protein SHAKE is NOT a meal. You STILL need to eat. Period!

    I use whey protein isolate with milk, never water. I always make sure to take it with a meal. It seems I might need more protein than the average person. If I don’t eat it at about 20 to 40 grams per meal I get really unstable and can start having some minor hallucinations from low blood sugar. Strangely enough, it feels similar to my experience on red yeast rice, but i was eating plenty! So i wonder of it’s also having an effect on my cholesterol.

    I have at least 1 to 2 tablespoons of butter with each meal, and as a small snack, dried vegetables and some pork rinds (though this is limited as my step dad says it’s unhealthy for me to be eating that many calories and fat).

    In fact the only time I really ever have any refined sugars is if I go out, which is practically twice a month. I still make sure to have protein and fat with it and only eat a LITTLE at a time.

    What are your recommendations for protein/fat/calorie intake?

    • Hi Zzg00gzz
      I don’t have macro nutrient recommendations. I just advise people to “Eat real food!”

      Types 2 diabetics and very obese people may need to adopt a proper LCHF diet to minimise the insulin effect of both carbs and protein. This tends to be around 80% fat, 5% carb and 15% protein. You’re into this kind of territory then ( and someone else’s advice
      Best wishes – Zoe

      • I know protein does effect insulin, but it’s sure better than sugar or too many carbs! More sustaining and helps the brain make all of the feel good neurotransmitters too. People who are low in protein can suffer from mood instabilities and so can those with low fat.

        Fat and protein go hand in hand, but it seems it’s better to get more fat than protein. Also, the fat will help the proteins absorb slower, thus last longer. Makes sense in my case! if I have just protein it lasts only about 2 hours, but if I have it with fat, I can rave a good 4 hours. Tons of energy!

        Speaking of energy, did you know that coffee is better than energy drinks with synthetic caffeine? At least that’s what i’ve heard.

      • Also not to mention there were some Indians (I think they were) who suffered from eating too many rabbits. Why? Too much protein, not enough fat!!! What happened to them? They died from protein poisoning. The meat was too lean and so, without much fat, they were not getting a good balance of fat and protein. PROOF that high protein, low fat diets are bad for most people.

        As for cutting off the fat on your steak, ditching the yolks in eggs or skimping down on the skin of chicken, take note of just how much fat is combined with protein rich foods. Quite a bit.

          • It’s been linked to not enough fat which by the way is a nutrient. Cholesterol is the same it’s a nutrient.

          • I heard it was due to too much protein and not enough fat. It IS called “protein poisoning”. We need fat so it is technically a nutrient.

      • So what about people with low blood sugar? Is fat more in favor in that case? I’ve noticed that when my blood sugar gets low, protein does help…but not always. It does seem that I need some kind of fat along with it.

        I was reading a book by Julia Ross and she said that people who don’t eat enough protein can have mood swings and depression. Same with a low fat diet! So I’m thinking those two go hand in hand.

        Hope you have a merry Xmas and a HEALTHY new year!

        • Hi zzg00gzz
          Nice to see you again! So sorry for the delay in approving this – a month’s worth of comments have just appeared – I wondered why it had gone quiet!

          Protein and fat are the two essential macro nutrients – carbs are not needed. It is unnatural to get protein alone – you’d be into egg whites or skinless chicken breast or other nonsense, so protein and fat tend to come together in the most nutritious foods (meat/fish/eggs/dairy) and carb and protein tend to come together in things from trees and the ground (fruit, veg, grains etc)

          Julia Ross would be right if someone didn’t get enough protein, but protein is in everything (other than sucrose and oils/lard) so it’s difficult to get insufficient protein. Vegans/veggies can get insufficient complete protein – as this only comes in animals foods, so those who don’t eat animal foods need to get combinations of other foods to try to get complete protein. This would impact mood (as would insufficient B vits generally)

          Hope you had a merry Xmas and have a healthy 2016
          Best wishes – Zoe

        • I ask because protein makes the amino acids, such as tryptophan that converts into serotonin for our moods, which i’m unsure if fat contains. What I mean by more important is in the context of mood improvement because I’ve heard people who go on low protein diets also suffer from depression. I have gotten high while using a whey protein powder and the tryptophan content was quite high.

        • Hi Wendi
          We die without either, so they’re equally important. We need (complete) protein for essential (can’t be produced by the body) amino acids and we need fat for essential (can’t be produced by the body) fats and fat soluble vitamins.
          Best wishes – Zoe

  • Thanks so much for breaking this study down Zoe, I always look forward to your ‘coverage’ of these reported ‘findings’ when they hit the press. It seems like there is a big move towards (or a return to) high carb eating again with an emphasis being on the dangers of eating too much protein. It’s confusing as obviously no one wants to damage themselves. My own conclusion is that no study is trustworthy and that as Paleo takes off, the carb industry is going to hit back big time with alarmist warnings and findings of variable authority. I’m not actually Paleo but this popular swing away from carbs is bad for the grain industry.

    My doctor who I saw for a sprained ankle just the other day (Zumba inflicted) congratulated me on my weight loss. When I explained I was eating fat, butter, cream, eggs, meat, fatty meat and vegetables in unlimited quantities she nearly fell off her chair in horror and promptly insisted that I return to a ‘sensible’ carb based diet immediately or face the inherent health risks of a fatty meat based diet.

    Anyhow. I just wanted to comment on your comment higher above as you have finally come across “freelee the banana girl”. She is gaining a huge following and interestingly, often cites the studies you have dissected here herself but reads and reports on them as they are reported in the press – in favour of high carb.

    Its a confusing dietary world out there – I’m ever grateful to you for taking the time to inform us as you do here on your website.

    • Hi Anna
      You must be a club member to know about my recent bananas girl discovery! Thank you for your support :-)

      You’re quite right that the carb/grain/sugar industry is fighting back hard. We must never forget the power that we have as consumers. We could bankrupt every fake food company overnight simply by collectively ditching processed food. Here’s some more ‘sensible’ carb advice and what a real scientist made of it! Enjoy:

      Best wishes – Zoe

      • Zoe, you’re right, that’s a real scientist with crucial arguments. And engaging too. I’m told Prof. Pogozelski’s students call her ‘Pogo’.

        Here’s another good one in the same low carb/diabetes area. Dr Sarah Hallberg. Different but spot on.

  • Hi Zoe, enjoy your blog. This question isn’t related to the above topic but I thought you may be interested. I live in Sydney and today one of our tv news “headlines” was a report from the UK which apparently found that statins for older people reduce the risk of stroke by 30%. I did some digging and found the paper was published in the BMJ

    I am naturally fairly sceptical about anything good coming from statins but wondered if you are aware of this study and had any comment? Thanks.

    • Hi there – I’ve been having a chat with a journalist on twitter about that one. The crude incident rate is 0.47 per 100 person years. This becomes 0.53 per 100 person years vs 0.42 per 100 person years for a 30% difference. It’s the usual relative risk nonsense, headline grabbing nonsense and it’s still only association (not causation) even if the numbers were impressive.

      Oh – and did you see this more honest reporting in the article: “We found no association between total incidence of vascular events and lipid lowering drug use, either for use of any drug (multivariate model: hazard ratio 0.91, 0.76 to 1.09) or for statins and fibrates examined separately (table 2⇓)”. No association – oh – but we managed to take a sub set of data to find something – so it is very similar to this high protein blog!

      Stay skeptical!
      Best wishes – Zoe

  • Zoe,

    You’ve got me really concerned about your comments on extremely high protein diets.

    I lift weights 4 x a week. I am 6’ 3, I weigh 200 lbs, or about 14.3 stone. I have 12% body fat.

    I aim for about 170grams of protein a day. 40 — 50 grams of this comes from protein shakes.

    I do not drink crappy sugar filled protein shakes, I buy natural, unflavoured pure whey from myprotein and add my own (natural) flavourings.

    I consume plenty of water. I supplement with 5grams of creatine, daily.

    Is this really going to harm my kidneys? This would be against the entire standpoint of the bodybuilding community (possibly skewed opinion there!)

    I eat and lift weights for health, but now you’ve got me panicking!

    I couldn’t consume this amount of protein without whey – it would cost me about £15 a day in chicken breasts (organic free range!)

    Thanks for your time, I appreciate you are a busy person, but thought this angle was worth putting out there for the sake of learning.

    Thank you

    • Hi Oliver
      This has a useful rule of thumb for the LCHF diet ( It says to take your height in cm (190 for you) – deduct 100 – and that’s a guide for your grams of protein. BUT LCHF is known for being moderate protein and low carb – because protein impacts insulin – so this would be at the low end of a range…

      The more used rule of thumb is the gram of protein for every kg of body weight, which would again be 90 for you, but this is often given with a caveat that body builders may be doubling this.

      I’d ignore the body building community view of health – they are in the business of selling the protein whey that you’re buying, so they’re biased. Check that your product doesn’t contain soy(a) unless you want to effectively be ingesting oestrogen (think moobs and search on line for soy(a) details). Most people do what you’re doing to look good. If you’re doing it for health, I don’t think it is healthy – the question is more – just how unhealthy is it?

      You could be doing worse things for your health (smoking, being obese, eating processed rubbish etc). Creatine is also not great for kidneys. You’d be better off dog walking/swimming/dancing etc and eating real food (which whey isn’t).

      Not sure this helps
      Best wishes – Zoe

      • Thank you ever so much for replying. I squat 140kg’s for reps and run a mile in under 7 minutes (at 35 years old) so dog walking wouldn’t really tax me. But I do understand what you are saying.

        An interesting question is that people like myself who are athletically strong (training, not necessarily genetics), can do the things they can by going against your advice on certain things (ie high carb, high protein…high everything basically!), but at what price? What will my organs have to say, in 20 years’ time? (Of course I follow your advice 90% of the time – whole foods, quality meat and fish, lots of vegetables etc).

        What may be a greater case study, are two guys on YouTube – The Hodgetwins. They have well over a million subscribers on their channels. They are 40 years old, and are very much proponents of “If It Fits Your Macros.” I am sure you are aware of this idea. They do I am sure eat very well 80% of the time, but they go to McDonalds and a whole host of other fast food outlets (especially when trying to lose weight because they say they find it easier to track their calories as it’s all done for you already!) as long as it fits in with their macro nutrient intake for the day.

        These guys are in phenomenal shape, ripped with muscle and extremely lean. They don’t claim to be experts, or nutritionists, but just talk from experience on what they have done. They have a comedic slant on their videos, but this is a sideswipe at the so called ‘Broscience’ culture that permeates the fitness industry.

        Of course I am not suggesting anyone eats fast food, but it is interesting to me that two people can look like they do, by eating what they eat. But, the question is, how are their organs doing? Does looking like you’ve just stepped out of the Captain America machine have an inverse relationship to internal health.

        I am 99.9% sure they are not on steroids.

        • Hi Oliver – I don’t know what much of what we do does to our organs! I’m not sure the medical profession has much of an idea either! One study says X is good, another that it’s bad, another that it’s neutral.

          The common sense to me is – the more we move away from our natural diet and lifestyle (even hibernating in winter, sleeping little in summer) – the more harm we will do. It will be very individual and some people will get away with a lot and others with very little. Genetics will play a big part in this. I’ve just come across this idiot eating 51 bananas a day and not much else ( – is there room for anything else?! At the other extreme there are people with type 2 diabetes and chronic obesity if they have more than 1 large banana a day! There is no rule for all.

          There are tests for various things if you’re really concerned e.g. or c reactive protein for possible heart damage (which some body builders can get but more likely the ones taking things). My worry here would be – anything that puts you into the medical system risks you being medicated. You could walk in healthy and walk out with statins and BP meds and start a slippery slope! Always better to stay away from white coats unless you’re ill is my view!

          Sounds like you’re fit and generally happy with what you’re doing. You could try Cross Fit for a natural but seriously challenging work out? The dog has the benefit of being a stress buster during and in-between walks!

          Try not to worry – worrying is bad for you!
          Best wishes – Zoe

  • Wow I found thise really interesting. A lot of things i didnt realise but i have to agree with Lisa on ” that there’s also a Fictitious Okinawan Diet; (the FOD).” HaHa. Cant wait to read your next blog, nutrition is so important.

  • Thanks Dr Zoe for FMD: my BS detector pins the needle when “Mediterranean Diet” hits my retinae. Real LCHF researchers brave Canadian cold rather than cruising the Greek Isles on cheap Ouzo. It is interesting that our bodies have a good tolerance of a range of protein levels- one more reason not to track calories.

  • I had to laugh when I read your “Fictitious Mediterranean Diet” (otherwise known as FMD). This is so true! I’ve been visiting various Mediterranean countries for years, and have noticed the same thing. In fact, I was quite shocked the first time I went, since I had been brainwashed to believe in the Fictitious Mediterranean Diet.

    Not only that, but I’ve read that there’s also a Fictitious Okinawan Diet; (the FOD).

    • And somehow industrially produced seed oils got added to the “Mediterranean” diet and no proponent talks about the snails and wild greens. Wild foods make alone make it a very different diet.

    • Many thanks Ash! I managed to get University access this time :-)

  • Zoe, thank you for taking another daft dietary paper apart. I think the public despairs of this nonsense and has mostly stopped listening. Sadly, that often includes good advice.

    Tonight on Channel 4 News we were told that obesity is increasing because vegetables and ‘healthy’ fruit are increasing in price more quickly than processed food. That’s not a good trend but the conclusion is ridiculous. I can buy a kilo of vegetables for a £1 and almost half a kilo of chicken liver in Sainsbury’s for a £1. The problem is terrible advice, ignorance and busy lives. Many people don’t cook and don’t know what to cook. I’m no shining example but I try and I finally found the LCHF way and learnt to prepare a few simple dishes.

    ‘Eat Fat, Stay Fit’ on ITV on May 8 was another step in the right direction and I’m grateful that you keep battling away on the public’s behalf.

    • Hi Stephen
      Many thanks for your kind words – all working together, we’ll get there!
      Best wishes – Zoe

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