I can think of very smart people who could be classified as overweight of obese, such as Gabe Newell, Linus Torvalds, or Steve Wozniak - so that makes me a bit suspicious. On this topic though, I do notice a significant drop in cognitive ability or "mental sharpness" from eating certain foods which have a higher GI. Have been experimenting with this lately, and I had wondered why after lunch time I wasn't able to focus as strongly as in the morning (I usually skip breakfast or eat light).
I don't think they're concluding "Fat people aren't exceptionally intelligent" or "Fat people aren't as smart as lean people".
What they found at the core of the study was that something in the fat cells was, in some way, contributing to decreased cognitive abilities.
So going along the lines of your initial thought, we can entertain the idea that "Newell, Torvalds, or Wozniak would have even higher cognitive performance than they already have if they exercised everyday and reduced their store of fat cells". That's more in line with what the article was suggesting.
You're probably being facetious, but yeah it could all be relative and we don't really know. Wonder if there's any reason they haven't tried this experiment on humans.
If you believe the study, the implication would be that Gabe's mental abilities may be reduced by being overweight, not that he would necessary be dumb / not smart as a result (ie he'd be even smarter - or perhaps his cognitive abilities would simply be faster, or memory better etc - were he to reduce body fat).
You're conflating success with intelligence. It is undeniable that Nowell, Torvalds, and Wozniak are all very successful people, what is unclear is how intelligent they are or if their success is primary due to their intelligence.
There's an awful lot of very intelligent people who never did anything with their life, and conversely there are a lot of perfectly average people who have done ground breaking things.
