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Health, Fitness and Nutrition Myths That Need to Die


Every day on social media, we're exposed to some variation of the same health, fitness and nutrition myths that need to die.

How these myths arose often seems buried in the mists of time, so much so that most people simply uncritically accept that they're true and act accordingly.

For many of them, they’re a masterpiece of the marketer’s art, demonstrating the power of repetition to the point that something simply becomes accepted as true.

What’s more annoying is that, as you’ll see, most of these myths have a kernel of truth nestling amidst the exaggeration.

In this article, I share what I know about each of these. I don't necessarily know exactly where they come from, but many of them clearly make no sense from an evolutionary point of view and I explain why I think this is.

Mostly, I hope this article will promote discussion and be an encouragement for us all to consider our beliefs around health, fitness and nutrition more carefully. It might even drive you to investigate the origins of some of these myths in more depth; knowledge that will help you to make better decisions about your habits in these areas.

We’ve all seen this one because it’s plastered all over the packaging of almost anything that could be considered fruit and veg, however tenuously.

For example, tomato ketchup can be considered a vegetable - although the typical serving size is too small to one of your five-a-day - despite containing pretty much nothing that actually resembles a real tomato or its ingredients!

The common belief, as it was told to me, is that this myth was created around 1991 by a collaboration between California vegetable growers and the National cancer Institute with the goal of selling more vegetables.

If this was the case, it’s hard to argue that they didn’t have improved health in mind, although promoting greater sales of vegetables is hardly a poor outcome for those who grow them.

I’ve also heard that it was the result of some earlier work by the World Health Organisation in a search for a way to reduce deaths from heart disease. Based on nutritional epidemiology, they concluded that people who ate more fruit and veg had fewer heart attacks.

Of course, the fact that there is a healthy user bias (people who eat more vegetables probably do other things to look after their health) in such studies and the fact that higher vegetable intake probably displaces food-like substances that cause disease might have escaped their notice.

In this case, they’ve committed the cardinal sin of attributing causation to association. What’s more, they’ve based their recommendations on nutritional epidemiology which, as I’ve often pointed out, is usually little better than creative writing.

Why do I believe this to be a myth?

I live in Great Britain, somewhere where humans have thrived for a long time. Even in the summer, you’d be hard-pressed to find significant amounts of fruit and veg growing anywhere for an extended period, let alone in the winter. Most of Northern Europe is the same.

This is significant because, for most of the year, the only thing that grows without significant farmer-input is tubers, which weren’t included in the WHO’s recommendation. If they were correct, we wouldn’t see evidence for thriving ancient human populations in Britain as long as 800,000 years ago and very much so in the last 40,000.

What’s more, the fruit and veg we now consume as part of our modern diet is a far cry from the small, fibrous, bitter, seed-filled items that would have existed then, and which required significant processing to make them palatable. Most modern humans would instantly reject those foods as inedible.

The evolutionary argument for a fruit and veg requirement doesn’t stand up. While they wouldn’t stand up as primary foods, there is no doubt that they served an important purpose in keeping our species alive in lean times.

I’m not saying you shouldn’t eat fruit and veg. Rather, I’m suggesting that if you like these foods and, as important, they like you, you should eat them to the level you choose. Should you chase a level of consumption even if doing so makes you feel sick? No.

We’re often told to eat a varied, colourful diet. I’ve heard this myth summed up as: “Eat all the colours” or “The healthiest diet is one that contains a lot of variety in the foodstuffs consumed.”

Once again, I don’t think this stands up to evolutionary scrutiny. If human health depends on this variety, then our ancestors would have struggled to survive. They wouldn’t have been the hardy souls they would have had to be survive so that we could be here today.

Most parts of the world don’t naturally support a wide variety of foods, especially colourful fruit and veg. Even where this variety would have been available, it’s unlikely to available year-round.

There is a reason to promote the eating of a large variety of foods and that’s to get you to eat more of it. Yes, once again, it’s a triumph marketing.

What’s at play here is the idea of palate-fatigue; the idea that if you eat the same thing all the time, you’ll eat less of it - or at least won’t eat beyond satiation/satiety - because you get bored with it. Eating something different fires up your appetite once again and you can eat more.

We’ve all experienced this when eating a large meal and getting to the point where we can’t eat another bite. Then the desserts arrive, and we suddenly have space for more. 

Interestingly, this is also a trick used by competitive eaters, who often overcome a sense of revulsion at the sheer amount of e.g. hotdogs they’ve eaten by eating a few bites of something sweet or salty in order to overcome palate-fatigue and keep eating.

There is a scenario in which eating a large variety of foods might be beneficial, and that’s if you’re eating a plant-based or vegan diet (not something I promote). Because most plants are generally rich in one or two essential nutrients and poor in others, combining them makes sense if you want to avoid deficiencies.

Not so for animal foods, a fairly small amount of which contain all the nutrients you need for health.

For optimum health, you don’t need variety, you need nutrient-rich foods. It doesn’t matter if they’re the same every day as long as you’re getting your nutrients.

Another of our pervasive myths that needs to die is that dietary fibre is essential for health.

This myth wasn’t started by Denis Burkitt, but he is the man who most heavily promoted the idea first introduced by people such as Peter Cleave, G. D. Campbell and Hugh Trowell, Neil Painter and Alec Walker. These folks had proposed a lack of dietary fibre as the cause for all kinds of disease, including dental caries, obesity, diabetes, heart disease and diverticulitis.

Burkitt noticed that people in Uganda who ate more fibre than people in Britain developed almost no bowel cancer. Making the same association equals causation mistake that so many do, he set about promoting dietary fibre as the cure.

What he ignored was differences in lifestyle, activity levels and the lack of sugar and refined grains in Ugandan people at the time. Seed oils were also virtually unknown in Uganda but had been introduced in the West as early as 1911.

Could it be another case of blaming a lack of fibre for what an abundance of food-like substances have done? 

There is certainly a case to be made for eating whole foods, which contain an amount of fibre bound up with the other nutrients; in other words, not drinking juice, making smoothies, refining grains and adding sugar, all of which make energy far too easily available to the body. But adding dietary fibre by eating things like psyllium husk or oat bran?

Just a quick word on constipation, which many people claim is caused by a lack of fibre. Constipation is NOT having infrequent bowel movements, it’s the inability to move the bowels when you need to do so. A number of studies have shown fibre to make constipation worse, not better.

Most dieticians and nutritionists are determined to die on the hill of dietary fibre necessity, but the evidence just isn’t there.

This talk by Dr Paul Mason is a good place to start if you want to investigate the fibre hypothesis. You may find places to disagree. That’s no bad thing, the idea is to ask why we believe what we believe.

Strictly speaking, a calorie is a calorie (the unit used in nutrition is kilocalories, but we’re all lazy and talk about calories). It’s a measurement of heat energy released when you burn something.

The amount of heat required at a pressure of one atmosphere to raise the temperature of one gram of water one degree Celsius that is equal to about 4.19 joules.

Two things which release the same amount of heat when you burn them can be said to contain the same number of calories.

The myth that all calories matter equally is a marketing message that you can trace back to Coca Cola through the International Life Sciences Institute, which is essentially a lobby group to “health-wash” the food-like substances they sell.

What they fail to tell us is that the body uses calories from protein, fat and carbohydrates in different ways in the body. There is a far higher metabolic cost in digesting protein (~25%) than there is in digesting fat (~2%) for example.

They also fail to mention the hormonal effects of ingesting the same number of calories as either protein, fat or carbohydrates. Carbs stimulate a large insulin release, fat stimulates almost none, and that insulin signals to fat cells what to do with the food just ingested.

Finally, this simplistic way of looking at food completely ignores the presence or absence of a host of essential micronutrients which our bodies will continue to drive us to seek until we get them.

So, yes, in a strict scientific sense, a calorie is a calorie. But in a nutritional sense, there is so much going on as to make that almost an irrelevance.

This myth follows on from the previous one and it’s the idea that you can consciously control your calorie intake and expenditure, thus losing weight. Adherents to this idea insist that it’s simply a matter of controlling the balance of calories in versus calories out and... voila, you lose weight.

First, I don’t argue that energy balance is a “thing”, it very definitely is. I do argue that it’s not under our conscious control. Our brains have sophisticated mechanisms for keeping our energy balance (and thus our body mass) in a fairly tight range. No matter how hard we try, we’ll always be driven to remain in that range.

Second, I don’t deny that it is possible to lose significant amounts of body fat by increasingly ratcheting down your calorie intake until you become very lean. Bodybuilders do it and have done it for a long time. 

It’s the ability of bodybuilders to get very lean that is used as marketing for the myths that you can lose significant weight, and keep it off, by counting calorie and macronutrient intake.

Here are a few dirty little secrets about very lean bodybuilders (and anyone who starves themselves):

  • They are starving themselves. Bodybuilding cuts are deliberate starvation, there is no other way to frame it.
  • The level of discipline and commitment required is off the charts.
  • The folks you see in magazines have almost all “had a little help”, if you know what I mean.
  • While on a cutting diet, the majority are the most miserable people you will meet.
  • They think about food all the time.
  • It can be the middle of summer and they’ll feel cold.
  • Their hormones are a mess (I’m not a fan of blood tests, but if you’re starving yourself, they make sense and the picture they paint isn’t a good one).
  • Once their contest is over, they don’t stay lean. That body fat goes back on quickly, giving the lie to the idea that this is a great way for you to lose it and keep it off.

In the Minnesota Starvation Experiment, conscientious objectors who were studied experienced the same types of symptoms. They also regained all the weight and more.

Anybody who has watched “The Biggest Loser” television show will have seen the conscious energy balance control myth at work. If you look up most of those folks now, they have as much fat now as they had at the start of the show, if not more.

Your body does not want to bend to your emotional or logical desire to shed body fat. Attempts to force it to do so using a conscious energy balance control strategy are you pitting your willpower against your evolutionary biology. It’s hard to figure out which one will win in the end. Ninety seven percent of diets fail; this is why.

This talk by Dr Zoe Harcombe is both entertaining and informative.

Again, you may not agree with all she says, but if it makes you think, it’s done its job.

It’s not unusual for me to encounter folks on social media who insist that nutrition really doesn’t matter, and that exercise is the most effective way to lose weight. Some have even built entire businesses on that idea.

The following tweet was one in a longish conversation in which the tweeter insisted that improving nutrition is ineffective and exercise is the intervention that actually works for weight loss.

I’ve included it not to embarrass the person involved (which is why I’ve blurred their name), but to demonstrate how this myth can actually blur what people read. There is a little clue in the phrase quoted in the tweet.

As is my way, I looked up this study, read it from start to finish and carefully checked the tables. I do this because I’m always open to learning something new. You can find the study here.

There is a lot of info contained in this meta-analysis and the researchers looked at a lot of outcomes, which they conveniently summarised in Table 1.

While a lot of it is interesting, the bit that applies to this myth is the following:

Diet resulted in greater weight losses compared with exercise. 
Dieters lost 2.8 kg to 13.6 kg of weight. 
Exercisers lost 0.5 kg to 4.0 kg of weight.

I’ve always insisted that exercise is important for health, but that it’s relatively ineffective for weight loss unless you also do something about your nutrition. What’s more, for weight loss, improving your nutrition is more effective even in the absence of exercise.

This meta-analysis bears out this view of the importance and role of exercise.

To get an idea of how effective exercise is for weight loss, we have to return to my old bugbear, calories.

Running 6 miles (<30 minutes for an elite, over an hour for many) requires about 600 calories. Although this varies a little based on how heavy you are, it’s close for all of us.

All well and good, but that number doesn’t take into account the calories you would have used just to sit on the sofa (we call that Basal Metabolic Rate) or what you would have used just to do the tasks of everyday life.

If you want to calculate BMR, you can use the following formulae...

Women: BMR = 655 + (9.6 × weight in kg) + (1.8 × height in cm) – (4.7 × age in years)

Men: BMR = 66 + (13.7 × weight in kg) + (5 × height in cm) – (6.8 × age in years)

So, a 75kg, 50-year-old male, has a BMR of 1653kcal per day, or ~70kcal per hour. This reduces that 600kcal to ~530kcal.

That’s still a fairly good return if you have a spare hour or so every day. Except that studies using doubly labelled water (the most accurate way to measure this stuff) have shown that where people increase their physical activity by, for example, running, they reduce their incidental energy output across the rest of their day. They do this unconsciously.

What’s more, exercising tends to cause us to become hungry; remember how your mum sent you out to play so that you could “work up an appetite”? With the exception of interval training, which temporarily suppresses appetite, this is another reason that exercise is so ineffective for weight loss: most people eat back the calories they used during exercise shortly afterwards. Gatorade anyone?

This myth leads to another, that of the ability of muscle to use more energy even when doing nothing.

[Those who know me know this, but I feel I need to point out that the use of “calories” as a measure of energy used is only for illustration purposes. I don’t count calories, I don’t encourage anyone else to do so and I believe the focus on calories in/out or shaken all about to be one of the least useful focuses in health and fitness ever devised.]

This is a really popular myth with trainers and coaches who really don’t like traditional cardiovascular training, believing it to only be there for burning more calories.

“If you build more muscle, you’ll burn more calories all day long.”

Like so many other myths, there is a kernel of truth here: you will burn more calories at rest for every pound of muscle you build, 6 kcal per day.

If you want to read one of the studies I rely on for this, it’s here.

Considering that a man who isn’t using anabolic steroids might be able to gain a pound, maybe two per month as a best-case scenario, by the end of a perfect year, you might be burning an extra 144kcal per day. Let me say it again: BEST CASE.

And that’s for a beginner in their first year or two. Aer that, it gets harder to gain muscle, with most men topping out at about 50lbs in a lifetime if they’re lucky and very dedicated. For women, it’s about half that number.

Instead of worrying about how many extra calories that muscle uses at rest, focus on working hard in the gym to burn those calories as well as all the good that the exercise and muscle synthesis are doing for you in terms of metabolic health, increased quality of life in older age etc.

My hair is too short to tear out, so this one makes me want to poke my eyes out every time I see it.

Let’s be blunt: running, in and of itself, does not and never has destroyed anyone’s knees. Humans are uniquely designed to run upright, in the heat, on multiple surfaces and for long distances.

What destroys knees is how you run.

This could refer to the stupid belief, promoted by many public health agencies, that you should just go out and run to lose weight because running is simple and cheap. If you have significant amounts of weight to lose, you should not go running to do so!

The forces you experience when running are multiple times your body weight on every stride. If you’re 100lbs overweight, you’re overloading your knees with the equivalent of a male Asian elephant every minute you run.

So, people who are significantly overweight should not run.

The second way you could interpret this is doing too much too soon.

I forget where I heard this years ago, but I’ll never forget it: 

It takes about 5 days for a muscle to remodel itself after a significant stress (not injury). It takes about 260 days for tendons, ligaments and other connective tissue to do so.

Or to put it the way Howard Luks does...

The joint capsule of your knee is made of and supported by a host of connective tissue. Run too much too soon and you will probably damage it. Once again, it’s not running, but how you run that matters.

Finally, this could refer to your running technique. The advent of running shoes and running coaches in the late 80’s and early 90’s led to a plethora of people running in ways that are not ideal. 

We see long loping strides with a heel strike far in front of the body that acted as a brake on every stride (huge forces through a straight, locked knee), low stride counts that allowed runners time to bounce high into the air so that they landed with even more force, shoes so soft as to be like running in sand and control shoes that completely removed the role of the foot in managing the forces and the working of the ankle knee and rest of the kinetic chain.

It’s not running that hurts people in this scenario either, but how they run.

Anyone who denies that humans are built to run is denying our evolutionary history, the very thing that made us human and contributed to our species dominance in the first place.

I understand that many people don’t like running for one reason or another. I also understand that some people have orthopaedic issues that preclude them from doing so. Better to be honest about your own limitations than to write off a fundamentally human activity as inappropriate or even dangerous.

You can read more about running for non-runners here.

This, like so many myths above, takes a truth and magnifies it to the point of absurdity.

Here’s the truth: IF you are an elite athlete, the specialisation demands of your sport might make training outside of that specialisation counterproductive.

There is an interference effect that endurance training has on strength and strength training has on endurance. But unless you’re an elite athlete, this effect is so small as to mean nothing to you in real life.

That’s it in a nutshell.

The benefits of cardiovascular training for your heart are hard to argue against. And with heart disease being the biggest killer worldwide, it just makes sense to include some CV training. You don’t have to run marathons, you just need to do something; ride a bike, go swimming, walk or even run gently on a regular basis and you’re good.

Similarly, strength training has huge benefits for quality of life as we age as well as the association of muscle mass with metabolic health. Again, it simply makes sense to include this, even if your personal interests lie more towards the endurance end of the exercise spectrum.


That’s it for now.

I wrote a longer list of myths to address and started to write about them, only to discover that they would require an article in themselves. For example, once I got started on LDL cholesterol, it seemed I would never get done. With that in mind, that will be a stand-alone article.

What I hope from this article is that you’ll examine things that you believe and assess whether they’re based on objective truth or someone’s marketing.

Perhaps you have your own pet hate myths that you’d like to discuss; feel free to pop them in the comments below.

I fully accept that we might not agree on everything, but if the article sparks thought and discussion, it has done its job.

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Will Newton

In over twenty years of coaching, I have coached everyone from absolute beginners to world champions.
My interest in getting the best results for people who train for health and fitness or the love of sport, rather than as professionals, drives me to find the most effective ways to get results.
My mission is simple: Be in better shape at 70 than most people are at 20, and to help you do the same.

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