My exercise physiology professor was pretty funny. He would say things like, “Thinking about that just makes my ass pucker.” I have to tell ya, there are some things that make mine pucker too. One of those things is when correlation is taken and twisted into causation. This drives me CRAY CRAY! Many don’t know the difference between the two and have never really pondered it and that’s ok. I’ll take you to school.Let’s start with an example from good ol’ wiki,
Sleeping with one’s shoes on is strongly correlated with waking up with a headache. Therefore, sleeping with one’s shoes on causes headache.
The above example commits the correlation-implies-causation fallacy, as it prematurely concludes that sleeping with one’s shoes on causes headache. A more plausible explanation is that both are caused by a third factor, in this case going to bed drunk, which thereby gives rise to a correlation. So the conclusion is false.
Here’s one that almost got me recently…
Nearly three quarters of prisoners fall into the two lowest reading levels. Many would read this and think, “Well golly gee! That means that a low reading level is the cause of imprisonment for nearly 75% of offenders!” Hold your pants on though. Can we all think of other things that could contribute to this? Children who never learn to read past a third grade level tend to come from what kind of home? They tend to have high rates of unemployment as well. I could list other CORRELATIONS here but my point is this: it could be their reading level, it could be their family and home environment, it could be their struggle to find and keep a job, or it could be a combination of all those things that contribute to someone finding themselves in the slammer.
Now what about this?
There is a strong correlation between those who are overweight an obese and heart disease, Type-2 diabetes, and other “obesity related” diseases. Therefore, being overweight or obese causes heart disease, diabetes, etc. But guess what? Most people who get these “obesity related” diseases aren’t eating well and they aren’t active or exercising and they aren’t good at managing stress. If you have ever watched “The Biggest Loser” you have seen the doctor with the bad hair scare the crap out of the morbidly obese contestants when they first get to the ranch. “You’re 50 but your real age is 75! You are going to die soon if you don’t get control of your health!” So they start working out an insane amount (seriously, insane) and they start eating tons more fruits, veggies, fish, fiber; stuff we are told that is good for us. A month or two later they go back to the doctor with the bad hair and he is praising them, “ You’re blood pressure is under control, your type-two diabetes is gone and y our lipid levels are under control!” But they are still at this point obese or morbidly obese. So is it how much they weigh or their diet and physical activity? Chew on that.
Often times with correlations, we are just hearing part of the story (or the research) or a lot of times, the whole story just isn’t known yet. There is SO much correlational data out there on weight and health outcomes! It’s just insane! Why is there no absolute perfect diet that prevents disease better than all the rest? Because we just aren’t there yet! Mediterranean, paleo, vegetarian, vegan, raw… they all tout amazing health benefits! They all have research that shows wonderful correlations, but we don’t have enough good conclusive research that shows say, a paleo diet trumps the others in health benefits (sorry crossfitters). So how do you choose what healthy diet to eat? I’ll get to that in a later blog.
You can indeed be fat and fit. It’s true. You can also be model skinny and be super unhealthy. Also true. The skinnies won’t get hounded about their weight when they go into the doctor for a sore throat though, even though their body could be in worse shape than someone who is overweight. About once a week I’m taking you guys through a book called, “Health at Every Size.” Read those posts. The research and the information I’ll be sharing is fascinating. These posts will also bring to light a lot of “fatism” and lame cultural norms with body shapes that we have all become accustomed to. That stuff also makes me pucker.
There is so much more to say about this but I’ll have to divide it up and save it for future blog posts. For now, try to question the stuff you read and hear. More often than not when something is presented as fact, if you listen close enough, you’ll hear, “may… is linked to… is correlated with… is associated with…” and remember these phrases don’t mean that going to sleep with shoes on causes a headache.
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