Correlation vs. Causation

Sohee Lee

Tags rant

Today’s article counts as more of a rant than anything, but I feel that this needs to be said lest I crack my forehead open from banging my head against the wall too many times. I’ve noticed a very common trend in the fitness community and beyond. I’ll keep this one relatively short for ease of read; I have a feeling I’ll find myself referring many individuals back to this piece.

Before you go on and make any kind of claim that you did x and therefore y happened, I urge you to please, please consider the difference between correlation and causation.

It’s very easy to fall into this trap. You change some behavior or adopt a new habit, and all of a sudden, you attribute that new thing as the cause of your success or failure.

But let’s rewind back to that high school science class for a few minutes here. Yeah, remember those times? It’s time to swat away those cobwebs in your brain and brush up on one of the basic foundations of none other than the scientific method.


To better illustrate today’s message, let me use a few examples:

  1. I dropped 20lbs of fat by eating six meals a day consisting of clean foods – no cheese, definitely no dairy, certainly never any of that God-forbidden fruit.


  1. I lost weight because I ran a half marathon every day, therefore cardio is an effective way to shed fat.

The above two statements are those of correlation, not causation. Please, let’s not confuse the two.

The process of going about establishing a causal relationship between two variables (in this case, changed dietary habit/ exercise and fat loss) is much more complicated than determining a correlational relationship. With the former, you must control every single condition except for that which you want to test – and in everyday life, doing so is often unrealistic and not feasible. With the latter, all you have to do is show that as x variable changes, y variable tends to change in a certain way.

Want to prove that small, frequent meals are the magic secret to an enviable physique? Okay, fine. But first, make sure that every other possible factor remains the same. Don’t change the total number of calories consumed; don’t even change the types of foods eaten. Don’t alter physical activity levels, amount of sleep, level of stress, or even coffee consumption. We don’t want any kind of selection bias when choosing your sample population, and oh yeah – make sure your sample size is large enough.

How about this well-known example: The rooster crows every morning before the sun comes up, therefore the rooster is what causes the sun to rise. How ludicrous does such a claim seem to you? Yet this is what so many of us do in the realm of fitness without even realizing it. Sure, there is a temporal relationship between the crow and the rising of the sun, but… even if the rooster doesn’t crow, I assure you the sun will still come out tomorrow. (Annie told me so.)

Reasons for the Confusion

There are many reasons to confuse correlation with causation. Below are the most common ones.

Confounding factor. See rooster example above. Yes, you lost fat, but not due to your frequent feedings. Rather, there was a third variable that you forgot to take into account: decreased calorie consumption. You not only took many of the calorie-dense foods out of your diet, but in doing so, you ended up ingesting fewer calories than you previously did, hence the weight loss. And don’t tell me when you started running all those miles you also didn’t start watching your diet at the same time.

Confirmation bias. Often when you go about investigating a question with a specific answer already in mind, you skew and misinterpret the results so you actually get what you want. Cherry-picking? Yeah, don’t do that. Any decently educated individual will immediately call you out on your bullshit and make you look like a… not-so-decently educated individual, to put it nicely.

Mere coincidence. I don’t think this one requires further elaboration.

So Before You Make a Claim….

Do yourself a favor and think twice as to whether the Shakeweight actually works or if it’s everything else you’re doing – such as eating right and training properly and getting enough sleep. Maybe, just maybe… it might be the latter. And maybe, just maybe… you’re successful in spite of some idiotic behavior you’re practicing (such as That-Which-Shall-Not-Be-Named, aka superfluous implementation of cardiovascular bodily hustle and bustle).

data of mountain murder 

And this concludes my rant. You may now resume your lives.

Oh yeah, and don’t forget to eat your protein and lift heavy sh!t. Have a good day. :)

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