Being obese puts physical stress on the body. It also makes it more likely that you will develop one or more weight-related chronic diseases. The effects of obesity may not be limited to only these outcomes, however, a new study suggests. Your brain and cognitive abilities may be affected as well.

Chronic diseases such as type 2 diabetes and other metabolic disorders are often the result of obesity, and once a person becomes overweight, it may become more difficult to be physically active. It's a slippery slope: physical limitations may also follow. While these effects of obesity have been well-studied, the relationship between obesity and mental capacity hasn’t gotten as much attention.

A high-fat diet and weight gain may lead to mental exhaustion.

Researchers at Southern Illinois University Edwardsville decided to take a closer look at how obesity affects the brain by studying the effect of a high fat-diet and obesity on two groups of rats.

One group was fed a high-fat diet, while the other ate a regular diet for six weeks. Twice a week the rats’ weight, blood sugar and ketone levels were studied. In the fifth week of the study, the animals were given an open-field test to measure the speed and distance at which the rats moved through a maze during a given time frame. Their level of physical exhaustion was measured. During the final week of the experiment, the rats were presented a novel object recognition test which analyzed how long the rats spent looking at new and familiar objects.

Both groups of rats gained weight during the study, but, of course, the group that ate the high-fat diet gained more. Their blood sugar levels fluctuated more, too, but there was no difference in the average levels of glucose or ketones between the two groups of rats. The rats fed the high-fat diet did poorly on the novel object recognition test, suggesting that their high-fat diet and weight gain had led to mental exhaustion, explained Chaya Gopalan.

There are many things you can do to help preserve your cognitive abilities as you age. Work to reach and maintain a healthy weight, or a body mass index (BMI) of less than 25. Find a healthy low-fat way of eating that focuses on fruits, vegetables and whole grains and agrees with your lifestyle; then, stick with it. The Mediterranean Diet or DASH Diet are two diets to consider.

“One message from this study is to avoid [a] high-fat diet, which not only makes one become obese, but also has consequences on cognitive capability,“ the authors wrote. Keeping your social connections can help preserve your brain health, so eat well, maintain a healthy weight, stay physically active, don't smoke, limit your alcohol intake and definitely get enough sleep.

The study was due to be presented at the APS annual meeting at Experimental Biology. Although the meeting was canceled in response to the COVID-19 outbreak, the research team’s abstract is published in this month’s issue of The FASEB Journal.