Obesity is not only bad for our bodies, but being overweight appears also to diminish our brain's ability to think, remember and reason, Science News reported.

Researchers from Kent State University in Ohio tested the cognitive functions of obese volunteers and compared them with healthy people. In general, the obese participants' scores were lower than their healthy counterparts. In some of the tests, including on memory exams, nearly 25 percent of the obese participants scored low enough to be considered learning disabled.

After the initial tests, two-thirds of the obese participants underwent weight loss surgery and lost, on average, 50 pounds in three months. In a second round of tests, the group that lost weight boosted their scores, including their memory test scores, significantly. This was not true for the group that did not lose weight.

This is not the first time scientists have made a connection between health and cognitive function. 

In this study, the researchers also used magnetic resonance imaging to see inside their subjects' brains. The obese subjects tended to have damage to a particular substance that surrounds and insulates nerve fibers in the brain, suggesting that substance is needed for optimal cognitive function.

John Gunstad, who led the study, told Science News the damage could be a problem for signals trying to get from one place to another in the brain.