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Nutrition is not a belief system.
Why wishful thinking won't get you results, but science might.


Nutrition is often seen as a belief system. In other words, the answer to “What should I eat?” is often based on faith, magical thinking, emotional attachments, and/or what feels “truthy”, rather than on real evidence or the scientific method. Until we fix this, nutrition will get more confusing, not less.

(If you want to see the PN Supercoaches Robin Beier and Jon Mills discuss this article in even more detail, check out the video below. If not, simply scroll over the video player or click here to jump to the next section.)

PN coach roundtable: Robin Beier and Jon Mills discuss the impact of seeing nutrition as a belief system


Imagine the Google search by someone who wants to eat better.

They might want to lose weight. Or build muscle. Or stay a little healthier so they can play with their grandkids longer.

So they might look for terms like:

Healthy eating.

Healthy diet.

Good nutrition.

The result? Well…

“Healthy eating” gave me 63.6 million options.

“Healthy diet” gave me 188 million options.

And “Good nutrition” gave me a whopping 213 million options.

When I check out some of these search engine results, I notice something.

Each of these websites has a story to tell: A story about which diet, supplement, food, or nutrition practice someone believes is best.

Many of these stories completely contradict each other.

But they have one thing in common: The authors treat nutrition like it’s a set of beliefs, there for their own picking and choosing.

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Unfortunately, “nutrition” is often seen as a belief system.

But beliefs don’t necessarily have anything to do with facts.

When we believe something, we choose to accept that it’s true, which may or may not have anything to do with factual certainty.

This approach of “believing” is frequently applied to nutrition.

As in:

“I believe that sugar is poison.”

“I don’t believe that humans were meant to eat grains.”

“I believe in only eating foods that are natural and organic.”

In other words, the answer to “What should I eat?” is often based on faith, magical thinking, emotional attachments, and/or what feels “truthy”, rather than on science.

Yet nutrition is not a belief system.

Nutrition is a science.

I’m a strength coach and PN Certified nutrition specialist.

(I completed the Level 1 Certification in 2013 and the Level 2 Certification a couple years later).

Most of my work is with professional and amateur athletes. And my job is to use nutrition (plus strength and conditioning) to get my clients the results they want.

When your meal strategy can be the difference between getting a multi-million dollar contract and not, there is no room for “hoping” the nutrition will work.

I can’t go on faith alone. My clients’ careers literally depend on me doing my job well. Which is why the scientific method, not beliefs, govern my practice.

For example, my client Ronda Rousey, a mixed martial artists, model, and actress, doesn’t care about what I believe about food. She only cares about what I know about nutrition’s effect on her body and performance.

That’s why I need to ensure that my nutrition recommendations are based on measurable, accurate reality. On science. On the best evidence that we have right now.

And physiology is physiology.

Believing something, or wanting it to be true, or feeling it should be true doesn’t mean it is true.

Physiology (like chemistry, like physics) follows certain known principles.

That’s why we research things like macronutrients, hydration, and/or supplementation. That’s why we try to understand the biochemistry of digestion and metabolism. That’s why we learn about things like osmotic gradients and the physical structures of cells and molecules.

It’s why we ask questions like these:

And we use a particular method for determining the answers.

These are just a few examples, of course. As you can imagine, scientists have thousands of questions about optimal nutrition, and they’ve answered some questions more thoroughly than others.

But, in short, we’re trying to understand as much as possible about the biochemistry of digestion and metabolism, so we nerd out about things like osmotic gradients and the physical structures of cells and molecules.

Knowing the science behind the field allows us to make evidence-based recommendations to create a known physiological effect.

Will honey and cinnamon “rev my metabolism”?

Some people believe this (or want others to believe it).

But nobody knows.

Will creatine monohydrate improve my power output?

Now we’re talking.

We know some things about creatine monohydrate and its effect on the body, because it’s been scientifically studied.

Creatine monohydrate has a known chemical structure.

Creatine monohydrate has a known mechanism of action. It increases the phosphocreatine stores in your muscle. This can then be used to produce more ATP (energy), which is a key source of fuel for power, heavy lifting, and anaerobic events.

We know this because we have carefully experimented and objectively measured what happens. We’ve also reproduced those findings over and over.

See how that played out?

One claim is speculation based on, perhaps (I’m guessing) rumors about blood sugar and metabolism along with a few studies about cinnamon as an antioxidant?

The other is fact based on a documented physiological outcome.

The big problem:
Most people start with the internet.

Wondering what to put in your smoothie? What to eat before you work out? How much bacon you should eat?

There are all sorts of answers on Google, not to mention Facebook and Instagram.

You don’t have to look far to discover a charismatic person with an excellent body and sales pitch offering up their own beliefs as a “protocol” or “system”.

These systems tend to include:

  • A set of certain foods and/or supplements to eat. (Like acai berries hand-picked at sunrise.)
  • A set of certain foods to avoid. (Nothing a caveman wouldn’t eat. Nothing that isn’t “natural”. Nothing that’s been sold, bought or processed.)
  • Rules about how much to eat, when to eat (or not eat), and possibly even where to eat. (No food after 6:30 pm!)

If the belief system (or the person who invented it) is compelling or “truthy” enough, it can be pretty tempting to believe them.

After all, many of these “systems” come with lots of reasons to believe, including:

  • Irresistible promises
  • Clever branding
  • Photos, graphics, and other visual “evidence”
  • Testimonials and/or celebrity endorsements
  • Powerful personal stories (“If this guy did it, I can too!”)
  • Sex appeal
  • Scholarly citations pointing to studies that turn out to be poorly designed, fatally biased, or not yet replicated (a hallmark of — you guessed it — actual scientific fact)

Before you know it, you can’t remember the last time you didn’t put honey and cinnamon in your oatmeal…and yogurt…and tea.

We’re not bad for wishing something were true.

Just like Fox Mulder, sometimes we want to believe.

It’s very human, actually.

Belief systems can bring us comfort. Following a clear set of rules can be a huge relief to those of us that find nutrition confusing or overwhelming.

Belief systems can also make us feel like we’re part of something: A community that shares our values, aspirations, and desires. We may feel a sense of importance, identity, and belonging.

Bonus: We’re closer to our goals… together!

Not to mention, these beliefs usually promise the things we desire the most, whether it’s sparkling clean health, glowing skin, freakishly awesome performance, the body we’ve always wanted, or all of the above.

When we buy into a belief system, we’re looking for help. We want to make a change, or finally find a solution to a problem that’s bothered us for a long time.

That’s completely normal and natural.

The people who start or share a belief system aren’t bad, either. Most of them are good, genuine, positive people just trying to make other people’s lives better.

Again, there’s nothing wrong with wanting to believe.

Or wishing some things were true.

The problem happens when we base our own health decisions on emotional bias or the rules of a certain philosophy… and either ignore what science has to say about the facts, or perhaps have no idea whether such facts even exist.

Science is anything but simple.

It would be great if there was a single ingredient to cure cancer, or a single exercise to get you ripped.

But physiology isn’t simple, and neither is science. Especially nutrition science.

You might be able to find a study to support nearly any nutrition-related belief you want. This is especially true if the study was small, or sponsored by a particular interest (like a supplement company).

People who read research understand this. They understand the weight that the particular evidence holds, and where it is placed in the hierarchy of nutritional importance.

But a new trainer in the industry, or a mother looking to get back in shape, or a dude who just got a Type 2 diabetes diagnosis, may not know the difference. They may assume that if it was demonstrated in one study, it is a fact.

This isn’t how science works, and it’s not how the truth is discovered.

Did you know that drinking alcohol increases muscle tone?

Don’t believe me?

Well, imagine I’m telling you this while shirtless, smiling shiny white teeth, and sporting a six-pack:

“In 2013, a double-blind clinical trial found that men increased testosterone 17% after a low dose of alcohol. In 1987, another study found similar testosterone-increasing results. Finally, a 2000 study showed that alcohol also increases testosterone levels in women.

Understanding that alcohol increases testosterone, and knowing that as testosterone goes up, so does our muscle mass and strength, I conclude that we should all get drunk to get jacked! (Results may vary.)”

Of course this isn’t true though, right?

Because that would be ignoring:

  • Other data that suggest alcohol actually lowers testosterone, and the two studies that show it has no effect.
  • Data on how alcohol can harm our health and fitness.
  • The fact that alcohol contains 7 kcals per gram, which adds up quickly when you get drinking (especially if you add mixes), and then normally increases appetite shortly afterwards, which leads to further snacking. (Street meat anyone?).
  • The fact that I am always fully clothed when telling clients stuff.

Instead of picking just one study, you have to look at all studies on that topic to see where the overall weight of the evidence lies.

But let’s get real.

People are busy.

Health and fitness clients don’t usually have the time, the experience, nor the interest to pore over research. They have jobs and lives.

So it can be easy to fall into the trap of taking one or two studies as gospel — especially if those results are delivered to you by a charismatic speaker with a great body. Enter my new supplement: Buff Booze!

What’s the harm in believing?

In the PN’s Certification programs, they talk about scope of practice. It’s crucial for health and fitness pros to:

  • Know what they know, and what they don’t know.

In other words, to make appropriate, evidence-based recommendations about nutrition, it’s not enough to simply:

  • Have made a big change to your own body (such as losing weight, or succeeding at a new sport).
  • Follow some blogs.
  • Have a stack of health and fitness magazines on the back of the toilet.

These are a great way to begin. I didn’t know stuff when I was new to the field, either. That’s why we learn and practice… and practice and learn… and then practice and learn some more.

But leaning on those methods of “research” — aka believing instead of knowing — can be dangerous.

There’s an old saying:

You know just enough to be dangerous.

For starters, beliefs without evidence can cause physical harm.

Nutrition can affect the human body’s systems dramatically — that’s the amazing power and opportunity, and it’s why we coaches love this field.

The downside is that doing the wrong things can change our bodies in ways we don’t want.

Back in the mid-to-late 1800s, a man named Wilbur Atwater had a Ph.D. from Yale in agricultural chemistry.

He measured the calories and macronutrients in hundreds of foods to eventually come to the conclusion that the only two elements that humans needed to be concerned with when creating their diet were:

  • protein, and
  • total calories.

He wrote newspaper columns, lectured, and told anyone who would listen about his beliefs. He truly believed that this was the solution to human nutrition and even poverty.

He was a well-respected scientist doing real research in a lab. Yet he didn’t have all the knowledge he needed to make the right recommendations.

Instead, he told everyone to eat fewer vegetables (because they were low calorie and low protein), while eating more fatty pork.

A little knowledge can be a dangerous thing, can’t it?

Atwater’s diet eliminates:

Thanks to research, we now know that all of these play their own unique role in health. Cutting out all of these nutrients is downright dangerous.

Now, this is an extreme example, perhaps.

But some of the most popular belief-based diets today have adherents alter their nutrition choices in strange and/or misguided ways. They:

  • Completely give up grains, beans, and legumes
  • Swear off all fat
  • Eat only raw food
  • Base their intake on a single food (e.g. grapefruit, cabbage)
  • Eschew solid food
  • Only drink “detoxing” juices
  • Hold their daily calorie intake to some “magic” number, like 600
  • Replace all carbs with bacon

These diets either selectively use research (for instance, a study in rats showing that grape juice prevents tumors — time for the magic anti-cancer grape juice diet!) or get stuck on small details while missing the big picture.

Also, beliefs without evidence can prevent the health and fitness industry from making progress.

Most people working as health and fitness pros chose this industry to help people change their lives for the better.

Confusing the crap out of ourselves (and clients) with these weird belief-based “systems” does not support that goal.

When we choose belief over fact, we don’t just hold ourselves, and our clients, back. We hold the entire industry back.

Let’s commit to improving everyone’s nutrition knowledge.

Our collective job as coaches is to create the healthiest and happiest people in the world.

How do we do that?

Treating nutrition as a science, instead of a belief system, is a strong step in the right direction.

As is constantly pushing to improve our own knowledge, and thinking critically about our convictions.

Nutrition science is a big field. We can’t know everything, and certainly not all at once.

But we can commit to putting the beliefs away and embracing a lifelong process of learning, studying, thinking critically, and applying evidence-based analysis to every decision and recommendation we make.

What to do next:
Some tips from Precision Nutrition.

1. Practice having an open yet critical mindset.

“Because it worked for me” is not enough evidence to recommend “it” to another person.

Be curious. Ask questions.

Explore the evidence that supports a given position. Be aware of why nutrition science is so complicated. Ask for scientific references, and then scrutinize those.

And, by all means, experiment on yourself (in Precision Nutrition Coaching, we call this writing your Owner’s Manual).

Try different things. Document the effects.

Over time, that’s as legitimate a way of knowing. (Make sure you’re always tracking and revisiting, though — bodies do change!)

2. Live in the middle ground.

Biology rarely operates in extremes. Only in very specific contexts (for example, actual diagnosed Celiac disease) do “always” and “never” have value.

So be suspicious of “always” or “never” language in nutrition talk.

Instead, try “some people” and “sometimes” and “it depends”.

For example, a coach might insist that everything should be “100% natural” or else it’s bad. But just because something has been processed in some way does always not make it inferior.

In some cases, processing can actually improve the desired effect and/or nutritional profile. For example, in 2011 the Journal of Nutrition published a report showing that without supplements or enriched foods:

  • 100% of Americans would not get enough Vitamin D.
  • 93% not enough Vitamin E.
  • 88% not enough folate.
  • 74% not enough Vitamin A.
  • 51% not enough thiamin.
  • 46% not enough Vitamin C.
  • 22% not enough Vitamin B6.

Sure, maybe there’s some “perfect” diet floating around out there, but for most of us, having a few fortified foods and even synthetic vitamins in the roster is probably a good idea. A diet full of processed, fortified foods and synthetic vitamins, not so good.

3. Notice when words and concepts trigger emotions.

Most belief-based nutrition systems are couched in marketing that purposely gets you worked up, maybe by poking at your traumas, insecurities, or ego (the current “clean eating” craze is a good example).

Recognize when you feel “pulled” by a certain idea.

Ask yourself, am I considering this “system” for the right reasons? Am I looking for an “easy” solution because I feel sad/frustrated/lost/stressed today?

4. Scrutinize claims that are tied to financial gain.

For example:

“Eat as much as you like and still lose weight!”
(A real-life claim aimed at selling a diet book.)

“Ripped abs in 1 minute!”
(Real claim. Workout DVD this time.)

“Control insulin levels, decrease blood sugar, speed metabolism, lower LDL cholesterol, burn belly fat and suppress appetite!”
(Real claims from the makers of a cinnamon supplement. That’s right, cinnamon.)

In my teen years, I spent unthinkable quantities of my hard-earned McDonald’s money on ineffective testosterone boosters and nitric oxide products.

Trust me bro, I was getting “jacked”.

In this marriage between beliefs and profit, science didn’t show up to the ceremony.

5. Be skeptical of one-size-fits-all approaches.

Trying to use the exact same macronutrient ratio (for example) serve every human’s needs and goals is a telltale sign that a coach needs more knowledge and/or has an emotional connection with the plan.

Humans are unique, complex systems. They should be treated as such.

There is no one best diet. Any plan should be a system that’s based on evidence, and truly reflects the client’s unique lifestyle, goals, and needs.

6. Get qualified coaching.

If you don’t feel confident reading research or understanding the science, consider finding a PN Certified coach or enrolling in the Certification yourself.

Knowledge is power.


Click here to view the information sources referenced in this article.

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