Fat But Fit But No

There’s a news story out today – apart from Bad sleep makes you look ‘significantly’ more ugly” – on whether the ‘fat but fit’ myth has been truly busted.

I’m not completely familiar with this ‘health rule’. I think it’s one of those things that they omitted to teach us in medical school (for example, like what toxins were), because, despite their popularity in the general world – they weren’t really a thing.

It’s an impressive story though. Researchers at the University of Birmingham have analysed 3.5 million medical records to see if those who were obese – but with no medical problems, or abnormal blood tests – would avoid illnesses later in life. The answer was no.

What’s impressive about this is the sheer numbers involved. It’s a problem to use a small number of people in a study, because you’re disproportionately likely to be affected by an abnormal result, or ‘outlier’. For example if there is one friend in your friendship group of four who is an idiot, then unfortunately it sounds like 25% of all people are idiots. When you would swear the number is higher. So the smaller the group or ‘sample’ the more it’s bound to be skewed. The bigger the group, the better the representation of what life is genuinely like.

So much of science is just how to get as close to the truth as the possible.

So it’s still not a definitive answer.

For example, the study still needs to be peer-reviewed before it’s published in a paper. This means that other academics will scrutinise it to make sure the scientists are presenting their results in the most honest way, and not just trying to ‘sell’ it. Even then, bad papers will slip through.

Also, it has been noticed that the cut-offs used for blood pressure and cholesterol may be too arbitrary. There’s something in this.

For example, we use the bell curves to work out what is ‘normal’ but inevitably we get people who are normal with abnormal results -they’re the outliers. However, that is a much bigger problem than just this paper, which a lot of medicine is prone to.

So – is it useful?

Yes! I would say so. A big study like this is helpful, as long as we keep the context in mind.

And what does it mean?

Basically we can’t give you the green card to not care if you’re overweight, even if your blood tests are fine. Not yet anyway.

Oh, and apparently not getting enough sleep makes you ugly.

So, no pressure.


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