Your Fat Is Why You're Not As Bright As You Could Be

Scientists have discovered that a chemical produced by fat goes into your brain and makes it slower. But don't worry: there's an easy fix. Just guess what it is.

Obesity doesn't make you less intelligent, but it might cloud your cognitive abilities.

In a recent study, conducted by researchers at Georgia Regents University, the blood of obese mice had especially high levels of a chemical called interleukin 1, a substance born from fat cells that can cause inflammation. When the researchers later examined the obese mice brains, they found that interleukin 1 had passed the blood-brain barrier—something that normally should not be possible. The substance had seeped into the hippocampus, an area responsible for memory and learning.

The mouse brains also had high levels of inflammation and low levels of a biochemical important to synapse function (synapses ensure messages travel efficiently between neurons).

These findings led to predictable results in how the mouse brains worked: Other obese mice did poorly on mouse-sized cognitive tests, presumably because the interleukin 1 was clogging things up. But the study didn't end there. The researchers wanted to make sure that it was the extra fat cells—and not something else—causing the disturbing brain changes in the mice.

Upon removing fat from the obese mice in a mini-liposuction procedure, the critters scored highly on the same thinking and memory tests they struggled with previously, and the interleukin 1 virtually disappeared from their bloodstreams. When the researchers put fat pads inside thin mice, those previously svelte rodents started doing worse than they had previously on cognitive tests.

Here's the good news: Major surgery isn't necessary to improve cognitive function. Exercise can make a big difference. As the New York Times explains, the researchers ultimately decided to put obese mice on a daily treadmill running regimen. Even though the treadmill runners weighed the same as sedentary mice after three months, they gained lean muscle and lost fat from their midsections. And, most importantly, they started performing better than the non-treadmill runners on cognitive tests. The brain inflammation? Gone. Synaptic health? Restored.

As with any mouse study, a disclaimer is required: none of these findings necessarily apply to humans. But what's the worst that could come from a little extra exercise?

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  • rmw2

    I find it remarkable how ignorant writers like this one are. If you are going to write about science please take the time to actually read the article thoroughly and know what you are talking about. Someone worked very hard on this research and your idiotic synopsis of it does not do it justice. Moreover, when you report on something and make outlandish claims "the public" will read it and draw numerous false conclusions. Thus, further spreading ignorance so try to avoid that in the future, for all of us scientists out there. I guess its not too hard to be a senior editor if you can actually get crap like this posted. I know undergrad science students that can write a better review than this.

  • Zack Oliver

    This article isnt exactly condemning fat people. For instance, I'm not fat. I have a little bit of fat. And I'd love to lose it. And such an article makes me go "hey, i might not to just look better but think and feel better? Nice!" Not only that, but the performance of your brain affects your entire well being as far as directing hormones for overall health. So, the better your brain function perhaps the better you age? A lower risk for cancer and health problems? Instead of immediately calling out the article for contributing to the anti-obesity narrative (as if any more is needed), you can praise it for it's pro-health and cognitive function narrative contributions. Yay!

  • I can tell you the worst. It makes my ADD worse and my libido go through the roof to the point I can't function at work. Someday I hope hyper people can work independently. Until then I need to be a drugged up slob to play well with others :)

  • Right. Please tell this to Oprah, Churchill (over his grave), Kevin James, Kathy Bates, John Goodman, Michael Moore, Shaquille O'Neal, Babe Ruth (over his grave), Benjamin Franklin (over his grave) and I could go on and on. If you substituted a race for the word "fat" everyone would be screaming, but it's still OK to marginalize people because of how they look as long as we quantify them as fat.

  • Zack Oliver

    Michael moore's movies are pretty crap...but they're not too far away from being decent. Perhaps losing some weight might lead to some better films

  • Being fat is not a "race" - that's the point. Being overweight is self-caused. Your genetics do have an influence on your metabolism and general health, but that is no reason to take it as an excuse to not maintain and improve your health. Your brain is a part of your body, so the correlation is obvious. Calling someone fat "stupid" is obviously incorrect because of psychological and socio-economic situations. But people with these types of problems should seek help instead of just shrugging their shoulders and saying, "well, I am just fat". The point is that everyone should want to be as healthy and live as well as they can. If someone has no problem doing their day-to-day routine while overweight, and don't experience any health problems, then obviously their weight is not a problem. The point is that most of the time, sadly, it can be.

  • Right. Please tell this to Oprah, Churchill (over his grave), Kevin James, Kathy Bates, John Goodman, Michael Moore, Shaquille O'Neal, Babe Ruth (over his grave), Benjamin Franklin (over his grave) and I could go on and on. If you substituted a race for the word "fat" everyone would be screaming, but it's still OK to marginalize people because of how they look as long as we quantify them as fat.

  • Zack Oliver

    One thing to think about: when selling to fat people, it helps to think on their level

  • The headline is nothing more than tawdry. Linking exercise to increased cognitive function is not ground-breaking, nor is it progressive. I could barely get past the headline, and I actively read and subscribe to Fast.Co,exist...therefore the takeaway from the headline alone "I told you so...fat people ARE stupid!" But don't fret, we're all in this together. You (yes, YOU), Me, and everyone else is fat and they have curated for you a non-scientific listing of what is making you and everyone else, fat. Wow, we're all one big happy family.

  • Brandy Vogeding

    Thanks, I was looking for more reasons to treat fat people like shit, and this really nailed it. Keep up the great work science!

  • It is amazing how much everything in our body works together. If one thing goes wrong it tends to affect a lot more than just that one area. I guess everything works that way and that is where the "Butterfly Effect" comes from. Excellent and informative article!

  • Daniel F. Dietzel

    Great article, though the last sentence is a bit of a copout. Mice are 95% identical to humans in their DNA (compare that to chimps which are 96%), which is why they're used for studies in the first place. Humans and mice are far more similar than you'd think.

    To write an informed article and then saying "Well they're just mice LOL" is doing a disservice to science and also painting these results in a discredible light.

  • To be fair I don't think the author said "Well they're just mice LOL" or anything like it. She's right, regardless of the percentage of our DNA we share with mice, the 5% that we don't is significant enough to mean that a lot of things work slightly differently in humans. To be able to say absolutely that this applies to humans would require testing in humans. I think it's a perfectly fair caveat that she added.

  • It's science, not politics or social assault. As a guy who's 40 pounds overweight from what he used to be at, I can clearly tell my body and mind do not currently function at the same level as they did when my system was more balanced and leaner. Don't get upset about reality. If you're fat, just be aware, no matter how brilliant you are, you'd function at a higher level if you weren't. Don't hate reality.

  • Eliza van Gerbig

    Perhaps the research is science but this article is far from it. The research is ultimately about the link between exercise and cognitive ability. There are tons of studies that show the many positive side effects of physical exercise from improved mood to physical well-being to, you guessed it, cognitive function.

    I'd ask yourself why you don't feel you're functioning at the same level. What caused the weight gain? Why aren't you moving as much? My guess is the answers have more to do with why you don't feel as "with it" than the weight does.