Why very high fruit diets are a *disaster* for most of us

February 5, 2012

 

Of the nutrition questions I’m asked most often, “What do you think about very high fruit diets?” is near the top of the league.

To be clear, we’re not just talking here about eating “a lot” of fruit.

We’re talking about getting the majority of our calories from fruit.

And the short answer is that I think this way of eating is a disaster for most people.

I say that based on:

  • my own personal experience
  • the experience of the majority of people I’ve spoken to who’ve tried it
  • extensive reading on evolution and diet
  • extensive reading on biochemistry

If I went into detail on all of the above this would be a very long article and I want to keep it short and sweet.

What to tell you?

Well…I’ll start with me.

When I first started to look into the concept of eating mostly fruit I fell head over heels in love with it.

I’m a sugar addict, so that was one reason.

But I’m also a sucker for simplicity, so when I was in my purest purist phase there was never a diet that more appealed to me; never one I more wanted to be “The One True Way” (back when I still thought that existed).

I’d read (as you may have done) that the key to making it work is that you have to eat mega quantities of fruit.

So not one or two bananas for breakfast but 10. Not a slice of melon, but the whole melon.

It was larger than a football but you’re still hungry? Have another.

Well, I tried it and no matter how much fruit I ate, I was hungry again within an hour.

I could sit down to a watermelon the size of a bowling ball at 9am and by 10am I’d be hungry again.

So, I’d have another “fruit meal”. Maybe a big green smoothie made with three bananas, a cup of berries and the rest of the blender filled with foliage. That would satisfy me for about an hour thanks to the greens (whereas a pure fruit smoothie never would) but by 11 I’d be wanting to eat again.

Perhaps I’d then eat eight peaches. All this would get me reliably bloated, but never sated.

I now realise that the term “fruit meal” is an oxymoron for those of us with a fast metabolism.

But I was so convinced this way was right that I let dogma guide me more than the feedback from my own body.

And my health, teeth, moods and energy levels suffered.

Most of us just do not have systems that are designed to run on fruit.

Fact.

And why would we?

It is not our “natural” or “species-specific” diet, as some proponents of this diet claim.

It is the species-specific diet of a distant ancestor of humans.

Which means, and this is key, a different species altogether.

Not a human one but a pre-human one, with a markedly different digestive system, which lived over four million years ago.

Humans have colonised the whole of this planet and it is a scientific fact that our species has shown itself capable of thriving in any of its diverse environments, as long as we eat the foods in that environment, in their natural state.

A fruit-based diet is natural in only one of these environments, and one in which very few humans live: rainforest.

There is nothing natural about living in England, or New England, and eating meals of bananas and mangoes. This is true in July, and even truer in January.

But please don’t misunderstand me.

I’m not saying the high fruit diet is a disaster for everyone. I’ve met people who’ve been eating high fruit long term and are getting great results.

But, as stated in the heading of this article, high fruit diets are a disaster for most of us.

If you’re doing well on a high fruit diet but have been eating this way for only a few months or a year or two, then experience tells me you may run into problems down the line as you run down your reserves of the nutrients that are lacking on this diet, while running massive amounts of insulin through your system (more on that below).

And if you’re (a) following a very high fruit diet but not feeling well on it, or (b) considering trying this way of eating, please read on.

The first fact to be aware of is that those who thrive, or could do, on a very high fruit diet long term are in a minority.

And if you’re in that minority, chances are good that you (a) live in a warm climate (or at least spend a large portion of your year in one) and (b) exercise a lot.

I’ve never met anyone who does well on this diet who doesn’t have at least (a) or (b) in a big way.

But to be clear, most people I know who live in a warm climate and exercise a lot, and who have tried existing on mostly fruit, did not thrive on it even short term, let alone long.

Location and activity level matter because:

By definition, a natural diet must be one where we source our foods from the environment in which we live. A diet based on fruit air-freighed in from thousands of miles away has only been possible for a couple of decades.

Imported fruit is almost always picked unripe so is missing key minerals and other nutrients needed for its digestion. This makes it an acid-forming and demineralising food choice.

Fine as an occasional treat. Not advisable as the basis of a diet for months on end.

Unless fruit is both seasonal and local, the small amount of nutrition it brings is not worth the large amount of sugar you take in along with it.

I’ve heard from so many on high-fruit diets who are eating six or more large fruit meals a day in order to stick to the diet, or even who are eating fruit every waking hour. Some basically graze on it all day long and never feel satisfied.

Why? Because (a) they are riding the blood sugar roller coaster and (b) the fruit is not giving them the nutrients their body is crying out for.

Chances are you know that there are planetary health implications to eating this way as well as personal health ones.

I’ve never met anyone in England who is following a fruit-based diet who isn’t eating boxes and boxes of air-freighted fruit every week for at least six months of the year. Carbon footprint: colossal.

The sugar intake of a diet based on sweet fruits is also colossal and that is why exercise is essential.

Because, and this is key, any time you eat more sugar than your body can utilise, your pancreas releases insulin to regulate your blood sugar. And the more sugar you eat, the more insulin it releases.

What this means is that if you eat a whole melon in one go, several mangoes, a bunch of bananas or any other large quantity of sweet fruit, and have not exercised hard within the last 24 hours, that will cause an insulin spike, and that is not a good thing.

And if you’re eating like this three or more times a day, you need to be exercising hard for hours a day.

As veteran raw food expert Dr Fred Bisci told me in our 2010 intertview, “Any time you consume a lot of fruit and haven’t been exercising very heavily to use all the sugar you’re eating, you’ll be secreting a lot of insulin. If your blood sugar is in the normal range after eating a lot of fruit and you haven’t been exercising heavily, that is only possible because you’ve secreted a lot of insulin.

“If you’re eating a lot of fruit – and especially if you’re eating it all day – you’re definitely going to have a lot of insulin in your blood on a consistent basis and this is going to lead to problems. If you want to do this you need to be spending five to six hours a day working out, which I do not recommend.

“It’s common scientific knowledge that if you have a lot of insulin in your bloodstream it causes inflammation in your arteries and elsewhere in your circulatory system, and this inflammation is a precursor to numerous different coronary artery factors.

“Not only that – when you do this, you’re stressing the beta cells of your pancreas, and also your adrenal glands and your thyroid. I’m seeing some people lately that are into raw foods that are running into adrenal and thyroid problems. This shouldn’t be happening. If you’re over-stressing your endocrine system this can definitely lead to serious problems later on in life.”

I personally think it is a good thing that most of us feel so terrible on a fruit-based diet we’re unable to stick with it long term. I believe we’re the lucky ones.

We feel perpetually hungry, light-headed, spaced out, tired, and/or any and all other signs of malnutrition and extreme blood sugar imbalance.

Some might encourage us to ignore these signs and carry on; that they’re “just detox” and to be expected.

Beware of believing them.

I’ve come across far too many people who started out with multiple nutrient deficiencies, adrenal exhaustion, chronic fatigue and/or eating disorders, and have made those problems much worse by eating high fruit.

It’s a diet that will, in most cases, only exacerbate those problems.

Those suffering from them – and indeed most of the rest of us, too – are much healthier and happier on a diet that is lower in sugar and higher in minerals and essential fats.

I think the reason so many stay on the high-fruit diet even when their bodies are giving them such clear signs it isn’t working is the seductive “natural diet” argument.

The one that had me convinced for years, too.

If it still convinces you, I recommend starting here.

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24 comments

  1. Anna said on February 6, 2012

    Great article! I think some people may thrive on it, but for how long? Will it make them thrive for years and years? And for those that are seriously sick and told to eat 30+ bananas a day, that is disgusting advice!!!!!!! I love my fruit, I loved having it in Costa Rica, it was amazing, but I just dont know what I think about this 80/10/10 diet as the diet ‘for everyone’ and it disturbs me when the people at the top of this ‘diet’ tell everyone to eat this way otherwise they wont be well. It’s just madness!

    Reply

  2. Apache said on February 8, 2012

    Awesome article. You’ve nailed it. I hope those considering a high fruit experiment on their own bodies take note so they don’t learn this the hard way like I did.

    Reply

  3. Jane said on February 8, 2012

    Thank you for writing this article. Hopefully it will help others trapped in the high fruit diet prison to let themselves out and find a more balanced way to eat and live. It will be a relief for many but difficult for most who will need to give up their idealism and fundamentalism when it comes to food. I have met many ‘high fruit’ proponents, who constantly cheat, eating far too much fat, chocolate and cooked foods. Why do they continue to deceive themselves and struggle to maintain the diet? Like any fundamentalist belief system, once a person is married to its ideals it is psychologically traumatic to break away. The ‘high fruit’ system gives their life structure, meaning and a place to belong socially. Most importantly the ego never wants to admit it was wrong.

    Reply

  4. Scottie said on February 9, 2012

    Amen!!!!

    Reply

  5. John Coleman said on February 17, 2012

    It’s true that maintaining and doing well on a high fruit diet can be challenging. Long term mineral deficiencies may arise if one does not eat enough greens or keep the calorie intake high enough. Living thousands of miles from our econiche presents many problems.

    That said I and many others thrive on high fruit diets.

    Our anatomy and physiology is still that of a frugivore. Evidence which I have published in my web site, and that is absent from the above article.

    BeyondVeg and the Paleo diet are full of fallacies and falsehoods.

    There’s a wonderful and in-depth debunking of Paleo diets on youtube called Primitive Nutrition.
    http://www.youtube.com/watch?v=egqf7k5Lzhk

    Reply

    • Sarah Best said on February 18, 2012

      Hi John – I don’t have time to check that video out now, but will do. Thanks for sharing it.

      I fully agree that Paleo philosophy is less than sound in some key areas – but I personally find BeyondVeg.com to be one of the best researched alternative nutrition sites out there.

      I did make a point of saying in the article that there are people who thrive on the high fruit diet, so I don’t disagree with you on that at all. But I know more people who’ve only got weaker and sicker on this regime and I believe the single biggest reason for that is that fruits are too high in sugar, and that this means regular insulin spikes, which is not good. And I think the secondary reason is nutritional deficiencies.

      Reply

    • Scott said on May 19, 2012

      John,
      Homo sapiens are biologically cooked food omnivores, with some raw. Homo sapiens and prior Homo species are not frugivores, as the norm. There can be exceptions, but I’m talking about the vast majority of people, worldwide, as it’s been for the past two million years, basically.
      My experience, since 1984, corroborates very much with Beyondveg (the fallacies are in 801010 and HCLFRV) and what Sarah here has shared.
      We’ll pray for you John, that you thrive.
      Best,
      Scott

      Reply

  6. Esmée La Fleur said on February 24, 2012

    It is not “sugar” in general that is the problem; rather, it is fructose specifically. Glucose is actually not much of a problem. All table sugar, high fructose corn syrup, and most fruits are 50% glucose and 50% fructose. Too much fructose from any source is not healthy over the long term. See Dr. Robert Lustig’s excellent lecture “Sugar: The Bitter Truth” here: http://youtu.be/dBnniua6-oM. It is 1.5 hours long, but one of the most important videos I have ever watched. I tried a fruit-based diet for 2 years and it was a disaster indeed. Lustig says he is not worried about people eating fruit, but of course he doesn’t know anything about the raw vegan fruit-based diet that many are now trying. I doubt he would encourage anyone to eat 30 Bananas a Day, lol…

    Reply

  7. Ben said on May 24, 2012

    sounds like you should read The Raw Secrets and Raw Controvercies. and if you wont read those, then good luck understanding what is meant by “detox” and how the body works/what hunger is.

    Reply

    • Sarah Best said on May 27, 2012

      I’ve read The Raw Controversies. I’m a fan of Frederic’s writing. I’m not quite sure, though, what point you’re making here.

      Reply

  8. Dale said on August 22, 2012

    Weak! A lot of statements based on congecture and emotion. There are very few facts stated here. I think most people just eat what tastes good to them not caring too much about what these foods do to the body in the long run. Im sure that the american population and the high rates of cancer, heart disease, diabetes, and hundreds of other diseases show this. Eat mostly fruits in season and add plenty of greens as well and you will see improved health.

    Reply

  9. Naomi Most said on December 10, 2012

    Thank you for writing this article.

    I gave the 80-10-10 thing a fair chance a few years ago. I never gave up eating a raw egg yolk or a few bites of salmon here and there (not wanting to take B12 supplements), but by weight, volume, and calories I was getting the vast majority of my “nutrition” from fruit.

    I felt very much how you did during those 6 months: spacey, hungry a lot, wanting to believe it was all “detox” and that things would resolve over time.

    At the end of my experiment I was skinny-fat (30% body fat at 135 lbs, putting me in a squishy size 10 — which is what I weigh NOW at 20% body fat and size 6 jeans), and no closer to transcendental levels of health than when I started.

    I gave up going to raw food potlucks because I was tired of hanging out with tired spacey people with hardly anything to talk about other than food, seemingly going to these gatherings to help re-brainwash each other to ignore the signals they were getting from their bodies that eating tons of (bioengineered, non-evolutionarily-natural) fruit was the wrong idea entirely.

    Reply

    • Sarah Best said on December 11, 2012

      Thank you for sharing that, Naomi. I can hear the high-fruit/low-fat brigade saying, “Well, of course it didn’t work, she wasn’t doing it right – salmon and eggs are not part of this diet.”

      To which I would say, you were eating these only in tiny quantities by the sound of it. If high fruit was the way forward for you, dramatically upping your fruit intake to the point where it was your main source of calories/nutrition should have made you feel better not worse.

      You had the results most people have on this diet, and that’s because it is too high in sugar and too low in essential fats and various other essential nutrients.

      I’m sorry to hear of your experience. Lucky you listened to your body and realised it wasn’t just “detox”. Many who ignore the signs and stay on the diet for longer run into problems that can be challenging to reverse.

      Reply

  10. Elly said on February 1, 2013

    I’m really glad I found your article, it describes exactly how I feel. I’ve been on a raw food diet for a few days now, and I’m feeling terrible. I mean, I could deal with the detox efects on the body, the headaches, the digestion, etc… But my mind is feeling muddeld, I’m unfocused and spaced out all the time, and I’m not liking it. No one can tell me that’s detox, I’ve done some seriuos detoxes before and none have made me feel this sick! I definitely do not reccomend this diet to anyone.

    That being said, I love the raw food diet – when it comes to vegetables. I have no cravings for cooked foods, so I think I’ll continue eating raw, just switch to more veggies and fats.

    Reply

  11. Skye said on February 2, 2013

    I myself have been eating a lot more fruits and veggies so far in 2013, and feel a lot more energy, clarity of mind and am sleeping better too. But I do think a diet that is only fruit/veg (80-10-10) could be dangerous for many people, including women with PCOS like me, which is an insulin issue. My body already doesn’t process insulin well, so to have a diet based on fruit sugars alone (which do spike blood sugars just as much as table sugar does)……doesn’t make sense for me. But to each their own.

    Reply

  12. marcus said on February 21, 2013

    All these different diets…Atkins, Vegan, Fruititarian, Paleo. Lol its all BS. Some rules I’ve collected as i’ve studied each of these protocols.
    1. Regardless of the composition of your diet overall calorie control is the most important tool. You need a caloric deficit to lose weight .
    2. You need to be an active human being. Sweat everyday for about an hour.
    3. You need a certain amount of protein to build or maintain muscle.
    4. Most diets fail after the first year because people are tired of being hungry. Figure out which foods provide the most satiety for YOU!
    5. Too many carbs, proteins, or fats can cause health problems. Eat a sensible, well balanced diet. Find a composition that works for YOU!
    6. If you can’t read the ingredients without pulling out a periodic table you probably shouldn’t be eating it.

    Reply

    • Sarah Best said on February 24, 2013

      Thank you Marcus – wise words!

      Reply

  13. sweet301 said on March 25, 2013

    Great Article. It was helpful. I once tried a high fruit diet and I felt exactly as you described; constantly hungry and I’m not highly active either so that wasn’t good. I never had intentions to be fully raw so when I had my curry chickpeas and rice with a raw kale salad for dinner I felt energized and great. I still love my fruit but I don’t try to eat 15-20 servings in a day.

    Reply

  14. blogblog said on July 30, 2013

    1. Humans ARE just another species of chimpanzees sharing 98% of our DNA with our fellow chimps. The fact that we are placed in a different genus – Homo – is based on 19th century convention not science.

    Chimpanzees eat 3-5 KILOS of fruit and leafy greens every day (equivalent to about 20-30 large apples).

    2. Humans have NO specific genetic adaptations to eating either high fat or high protein diets. Lactose tolerance simply means we can digest a milk SUGAR (lactose) not milk fats or proteins.

    3. Humans evolved in the tropics. The vast majority (>90%) of humans still in the tropics and subtropics. The fact that fruit isn’t available during an English winter is totally irrelevant.

    4. The peer-reviewed science is very clear that very high levels of whole fruit consumption is both safe and healthy.

    5. Fructose in the form of fruit does NOT cause obesity or metabolic disease.

    6. Farting is HEALTHY – it means that you are digesting high levels of fibre. High levels of fibre is ESSENTIAL to gut health and maintaining a healthy gut microbiota

    Reply

    • Sarah Best said on July 30, 2013

      Only a few years ago I would have agreed will all of those points. But eating high-fruit made me very sick, and has made many others very sick too – and for very good reasons that are rooted in the realities of human evolution, and what those realities mean about our nutritional needs. I stand by my claim that a high-fruit, low-fat vegan diet is a dangerous diet for most people.

      Reply

  15. Richard said on August 17, 2013

    This article is well written but is based in an incomplete understanding of metabolism. Firstly a diet high in sugar does cause insulin spikes, but so does a meal high in protein. Protein spikes insulin regardless if sugar or carbohydrate is present. So any meal you eat (unless it is a meal of pure fat) will significantly increase insulin. Whey protein for instance increases insulin as much or more than some carbohydrate meals. Next sugar does not turn to fat, unless certain conditions are met. It would be safe to say that most body fat actually comes from dietary fat. Next fruit based diets do have certain deficiencies. Most of these can be compensated for with a diet that contains lots of nutrient dense meals made with bone broth, liver, grass fed milk, meat, cheese, eggs, and well cooked greens, herbs and spices. Presently I obtain most of my calories from sugar from fruit, milk, and honey, I also eat pastas and other starches. The real problem is PUFA (polyunsaturated fats) which damages the organs, upsets hormone levels, causes inflammation, oxidation, promotes cancer and ultimately leads to disease.

    Reply

    • Sarah Best said on August 18, 2013

      Many thanks for your comment, Richard. My understanding has expanded a good deal since I wrote this article, especially now as I’m in full-time research mode for a book on these very topics :-) You are spot on about protein’s effect on insulin – a phenomenon I wasn’t aware of back then. But sugar turns to fat all too easily as sugar in the bloodstream ALWAYS triggers an insulin release. The more sugar, the more insulin, and insulin is the fat-storage hormone. Body fat comes from sugar/carbs primarily and excess protein next (due to the insulin connection you highlighted). Dietary fat is the macronutrient LEAST likely to turn to body fat, due to the fact it’s the one of the three that doesn’t trigger the release of insulin! I now realise that as long as we stick to good fats, we can consume much higher quantities than we’ve been told without gaining weight, as long as we’re not (a) eating silly amounts of it, or (b) triggering insulin surges by overdoing the carbs or protein. And there is no health downside either. In fact, good fats are essential for health and not getting enough of them is one of the leading causes of ill health. But I would certainly agree with you on fruit diets and deficiencies, and on the havoc wrought by diets too high in polyunsaturated fats – especially the ubiquitous omega-6s.

      Reply

  16. Adam said on October 14, 2013

    Firstly, great article. Very informative. However, I am always surprised to read how little diets never reflect MOVEMENT or what we call *exercise*

    Our society that we live in was not designed for movement but for economic profit.

    If you eat high amounts of sugar while sitting at a desk for 8 hours, how do you think you will burn off all that energy?

    I’m not saying get active for 5 hours, just moderate.

    Rule of thumb.. No packaged foods, no foods with additive numbers etc.

    Enjoy a BALANCE of various fruits, vegetables, organic meats, dairies etc. and MOVE your ass for a consistent period (walking/jogging/cycling/yoga/pilates for an hour).

    Reply

  17. Sarah Best said on October 14, 2013

    Excellent points, Adam. It’s easy to fall into the trap of obsessing so much about what we do/don’t eat – and of course getting caught up in everything else demanding our attention – that we forget exercise! A lot of people think they can eat what they want and “undo” the effects with exercise. Doesn’t work, but neither does doing everything else right but forgetting to move! Thanks for commenting.

    Reply

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