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?