Mental fatigue occurs when you spend sustained attention on demanding cognitive tasks. Mental fatigue can cause attention and efficiency declines, slower reaction times, and poorer decisions.
Researchers fed one group of rats a high fat diet and the other group of rats a standard diet for 6 weeks. All the rats were given a novel object recognition test in week 6 of the study. The test measures mental fatigue by examining how much time the rats spend exploring new and familiar objects. The high-fat diet rats performed worse on the test than the standard-diet rats, demonstrating mental exhaustion in the high-fat diet group.
Takeaway: A high fat diet may impair cognitive capacity by increasing mental fatigue.
Sepideh Kaviani, Paige Niepoetter, Coral Viernow, Hannah Ruholl, and Chaya Gopalan, The effects of diet-induced obesity in male Sprague Dawley rats on blood glucose, ketones and markers of mental and physical fatigue, Apr. 19, 2020, https://faseb-onlinelibrary-wiley-com.du.idm.oclc.org/doi/abs/10.1096/fasebj.2020.34.s1.07093.
Neuroscience News, High-Fat Diet Consequences include Mental Fatigue, Apr. 27, 2020, https://neurosciencenews.com/mental-fatigue-diet-16256/.