The Lung Cancer Analogy
A good analogy that I like to use to help explain the cause of obesity is that of smoking and lung cancer. Usually, I have to explain this when someone says something like, “Processed carbohydrates don’t cause obesity; my cousin eats muffins and pancakes and pizza and all sorts of pasta and he’s thin as a rail!”
Think of smoking. Statistically, more than half of habitual smokers will not develop lung cancer. That’s right; more than half of lifetime smokers will be lung-cancer-free. They will suffer from bad breath, yellow teeth, and cars you don’t want to ride in, but the majority will not get lung cancer. We all know some old, grizzled coot who has smoked two packs a day for 50 years yet remains as healthy as a mule and as sharp as a whip.
However, out of those who have gotten lung cancer, the vast majority of them are currently smokers or have smoked for a large portion of their lives. So smoking doesn’t cause the cancer in everyone, everywhere, every time, forever, and always. But out of those who have contracted the cancer, smoking is the cause.
In the same way, excess processed carbohydrate intake does not cause the accumulation of body fat in everyone, everywhere, every time, forever, and always. But out of those who have become fat, excess processed carbohydrate intake is almost certainly the cause.
Many who dismiss the Carbohydrate-Obesity paradigm like to point out populations that eat plenty of carbohydrate but have low rates of obesity and modern diseases. So obviously it’s not the carbs, otherwise they’d be fat, right? Case closed. These are the same type of people who use a floating balloon and a flying bird to disprove gravity. Turns out there’s other stuff going on.
This is the same as saying that since France has one of the highest rates of smoking per capita, yet one of the lowest rates of heart disease and lung cancer (both true), smoking doesn’t cause lung cancer. Case closed. Except the cause of most lung cancer is smoking. So what the fuck?
A good way to think about it is that excess processed carbohydrate intake does not always cause obesity, but where obesity has occurred, excess processed carbohydrate intake is the culprit. Smoking does not always cause lung cancer, but where lung cancer has occurred, smoking is the culprit.
For both of these disorders, the above causes were identified as part of the “null hypotheses”—the hypotheses that, based on observation, seem to be the case, and that we can consider true until they are disproven. This is very similar to the theory of gravity. If anything heavier and denser than air ever falls up, now you’ve got something.
Gravity will always tend to make things fall; when something doesn’t fall like it should, there is something else going on that is resisting its effects.
Smoking will always tend to cause cancer; when someone smokes and doesn’t get cancer, there is something else going on that is resisting its effects.
Excessive processed carbohydrate intake will always tend to make people fatter; when someone eats a ton of processed carbohydrates and doesn’t get fatter, there is something else going on that is resisting its effects.
So those are the null hypotheses that must be disproven through rigorous experimentation. So far they haven’t been. We’ve discovered plausible mechanisms that govern these phenomena and nobody has been able to show that they’re not sufficient.
Some have pointed out various instances where the effects of gravity in deep space are not behaving as Newton’s model would predict. But if those people have got a better explanation for why things fall towards the center of the Earth, I’d love to hear it.
Similarly, many have pointed out compounds in the body like Acylation Stimulating Protein, or ASP, which helps shuttle nutrients into fat cells. Rest assured there are still others that function in a similar way. The body is full of awesome redundant systems. The shrill calls of “You can still get fat without Insulin!” can be heard reverberating around the internet even today. Unfortunately, this is not the whole story.
Dig this: if you ever find evidence, anywhere, of any society, country, or group of people at any point in our recorded history who had high levels of obesity in the absence of dietary carbohydrate….WHAMMY!! Now you’ve disproven the null hypothesis; now you’ve got some ground to stand on. High rates of obesity in the absence of carbohydrate would be provocative. So would high rates of lung cancer in a population that didn’t smoke. Obesity didn’t even used to be a real thing, is not a real thing in the animal kingdom, and has only recently become widespread. Same with lung cancer.
The only way to disprove the processed-carbohydrate-makes-you-fat theory or the smoking-causes-lung-cancer theory is to find large groups of people who got fat without carbs or got lung cancer without smoking.
And while you’re at it you can tell me all about how babies don’t come from fucking since some people fuck all the time without making any.