High-fat diet consequences include mental fatigue

Summary: Rats fed on a high-fat diet were more mentally exhausted following a novel object recognition test than those fed a healthier diet. Findings suggest high-fat diets not only contribute to obesity, but they can also have an impact on mental fatigue and cognitive abilities.

Source: Experimental Biology

Obesity has been shown to place physical stress on the body, but new research suggests that excess weight may also cause mental fatigue. The research, originally slated for presentation at the APS annual meeting at Experimental Biology (canceled due to the coronavirus), is published in the April issue of The FASEB Journal.

Obesity can increase the risk of high blood sugar (glucose), which may develop into type 2 diabetes and other metabolic disorders if untreated. Impaired exercise capacity or physical stamina may also be a problem for people who are overweight. Compromised cognitive function, however, has not been associated as strongly with obesity as physical limitations.

Researchers at Southern Illinois University Edwardsville aimed to learn more about the onset of obesity and its impact on both physical and mental abilities by studying two groups of rats. One group was fed a high-fat diet, and the other ate a standard diet for six weeks. The research team measured the rats’ weight, blood glucose and ketone levels twice a week. Ketones are chemicals made by the liver when there is not enough insulin in the body to convert glucose into energy. In the fifth week, the researchers administered an open-field test, which measures speed and distance as the animals move through a maze in a given time frame and determines physical exhaustion. A novel object recognition test, which measures mental exhaustion by analyzing the time the rats spend examining new and familiar objects, was given in the final week of the trial.

Both rat groups gained weight during the trial, but the high-fat diet group, not surprisingly, gained more than the control group. Blood glucose levels fluctuated more in the high-fat diet group as well. There was no significant difference in the average glucose levels or ketones between the two groups.

The high-fat diet group performed poorly on the novel recognition test when compared with the control group. “Although we were not fully surprised by this finding, this is the first study, to our knowledge, to be reporting mental exhaustion in high-fat diet-induced obese rats,” explained Chaya Gopalan, PhD, principal investigator of the study.

This shows a man holding his head
The high-fat diet group performed poorly on the novel recognition test when compared with the control group. Image is in the public domain.

“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.

Gopalan’s team was slated to present “The effects of diet-induced obesity in male Sprague Dawley rats on blood glucose, ketones and markers of mental and physical fatigue” 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.

About this neuroscience research article

Experimental Biology
Media Contacts:
Anne Frances Johnson – Experimental Biology
Image Source:
The image is in the public domain.

Original Research: The study will be published in FASEB Journal.

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  1. This study is confusing and appears misleading. It first posits that the condition of obesity can contribute to not only physical stress, but cognitive as well. Then it shifts its focus to how a high fat diet is correlated with these maladies, with absolutely no specifics of what foods the 2 diets included. What constituted “high fat” and what constituted a “standard” diet? Not all fats are created equal. I noticed bias in the commentary, such as that “not surprisingly” those on the high fat diet gained more weight. It smacks of the old ‘fat makes you fat’ junk science that was found to be mostly promoted by lobbyists for the sugar industry. There is much evidence that a diet rich in healthy fats and very low in sugar/carbohydrates helps prevent obesity.

  2. Is there any way you could share what kind of fats they were ingesting? The study and the results are meaningless without knowing that.

    Was it a high fat diet based on avocados and fish or based on fried foods and soybean oil?

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