All the hard work you’re putting in the gym and kitchen to stay lean might be doing much more than ensuring you’re ready for beach season–it might keep your brain fit as well. 

A research study tested mice with varying levels of body fat has revealed that fatter mice are slower mentally because of the secretion of a chemical called interleukin 1 that seeps into the brain from the bloodstream. Interleukin 1, which comes from fat cells causes inflammation.

Researchers tested the mice as follows: “We used a treadmill training paradigm in which mice were exposed to daily training sessions or an immobile belt, with motivation achieved by delivery of compressed air on noncompliance.” What they found was that the mice with less body fat quickly realized that it would be better to comply with the testing rather than get an express delivery of compressed air. The fatter mice, however, took noticably longer to figure this out. 

To make sure that the reduced cognitive abilities were body-fat related, they performed something similer to a liposuction on some mice and added fat pads to skinner mice and tested again. The results showed that the lipo’ed mice performed better in the cognitive tests, while the results of the souped-up fat mice dropped.

Researchers discovered that fatter mice had higher levels of interleukin 1, and that it secreted into the part of the brain that controls short- and long-term memory and spatial navigation (the hippocampus) from the bloodstream, and fitter mice with low levels of body fat had very low levels of interleukin 1 in their systems.

The takeaways for us humans (our body fat shares very similar traits to that in mice): Burn fat. It will make you look lean, and it can keep your brain keen.