I have a maxim, "beware of British newspapers." I guess I should add the BBC to that list after reading this slapdash piece, Obese men 'have lower IQs'. Speaking as a normal weight individual with a BMI of 22.8 I don't have a personal axe to grind, but this study screams correlation does not equal causation.
The Boston study found that men with a BMI of 30 or more scored on average 23% lower marks in tests of mental acuity.
The authors make some noise about blood circulation, and I'm sure you can posit thousands of halfway plausible causative components, but perhaps fat dudes are just sluggish because they just ate before the test? Anyway, I suppose this is an example of a "contagious" meme. The science is plainly ludicrious, but it is pretty funny. And I am evil, so I guess it makes sense I would want to talk about obesity in somewhat mocking tones. Addendum: The same researcher has found a positive link between high cholesterol and IQ.