Is it safe to say that obesity is a risk factor for diabetes but not a cause?
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Establishing cause for anything is incredibly difficult. You have to be able to rule out conclusively that *nothing else* could be influencing the effects you observe in an experiment. Not random chance, not other factors, not the mere process of recovery or aging. This is very difficult to do. Often all we can see is correlations. Correlations aren’t meaningless, they’re useful information, but they don’t always tell the whole story. You can’t assume all of them are meaningful. Only some of them are meaningful, and it’s sometimes hard to know which is which.
All a “risk factor” is is a factor keeps showing up as a correlation. We keep doing studies that find that obese people are more likely to develop diabetes than non-obese people. We can’t necessarily say for certain. All we know is (making numbers up here) 1 in 5 obese has diabetes but only 1 in 20 non-obese people does. They could be unrelated, we don’t know for sure.
Establishing philosophically-certain cause-and-effect is nearly impossible. However if you keep doing studies over years and years and decades and decades, and you keep finding a correlation over and over again, and you do studies that try to control for this or that factor, and the correlation is always there, then scientists get closer and closer to being willing to say it’s a true cause, and not merely a risk factor. They did a gazillion studies on cigarettes and lung cancer. They keep finding this astonishingly large correlation, the science gets sophisticated, they control for all kinds of factors. And after several decades of this, eventually doctors got comfortable just coming out and saying: smoking causes lung cancer. None of those studies *proved* it beyond a doubt, none are like mathematically-logically irrefutable. But all combined together, no *reasonable* person could possibly doubt it.
Usually to deem something a “cause” you need a process that leads from the cause to effect. This is a pretty strict requirement especially with complex biological processes with many factors.
Most of the time, since experimentation is limited (ie you shouldn’t cause harm), researchers can observe limited samples and attempt to correlate diseases to likely factors. Gathering this data only results in establishing correlation. Correlation does not imply causality. So the precise term when there is a high correlation is consider the factor a “risk factor”.
Until the underlying processes are well understood, a factor should not be considered a cause. Eg we now know that bacterias can cause disease because we know how it works.
A risk factor is anything that heightens your chance of getting said disease or complication, when you eventually get diabetes most likely one, multiple or even all of the risk factors could become a cause.
Smoking is a risk factor for lung cancer, if you smoke your chances of getting lung cancer increase.
If you have been a smoker for the last 20 years and you get lung cancer, odds are good that smoking is the cause for your lung cancer.
* a ‘Cause’ is something that literally causes the outcome.
* Blunt force trauma to the head could be a ’cause’ for death.
* ‘Risk Factors’ are things that are correlated or associated with an outcome.
* Working on a slanted roof, 20 feet about the ground, with no fall-prevention or fall-protection equipment is a risk-factor for death.
* As others have pointed out something can be both a risk-factor, and a cause.
The word causation suggests a mechanistic link between an event and an outcome.
A risk factor increases the likelihood of an outcome.
In regards to obesity and diabetes, the picture becomes somewhat confusing as the mechanism is driven by multiple causes. Adiposity is a risk factor (increases your chances) and mechanistically drives disease (via hormonal changes).
Adiposity is also an indicator of other underlying causes/risk factors which are linked to diabetes e.g. obese people are more likely to consume a diet high in sugars and simple carbohydrates, exercise less etc. These behaviours are themselves independent risk factors for both diabetes and obesity.
In other words it’s complex and RFs and causal mechanisms interact with each other.
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