Introduction
The purpose of an article published in BioMed Research International by Rima Solianik, Arturas Sujeta, Asta Terentjeviene, and Albertas Skurvydas (2016), all members associated with Lithuanian Sports University and the Institute of Sports Science and Innnovations in Kaunas, Lithuania, was to determine the effects that a 48 hour zero calorie diet has on brain activity, mood, cognition, and autonomic function in amateur weight lifters. The article introduces fasting rituals for religious purposes, for weight loss, and for treatment and prevention of disease (Sujeta et al., 2016). What is of interest is that with decreased or lack of calories, an increase in sympathetic activity and stress to the prefrontal cortex compounded with a lack of available glucose can lead to decreased brain activity and mood alterations (Sujeta et al., 2016). The goal of this study is find out how a fasted diet will affect amateur weight lifters’ prefrontal cortex and hippocampus mediated tasks (Sujeta et al., 2016).
Methods
Nine men were utilized in this study based on the guidelines that follow: age 20-30, at least 1 year of resistance training, nonsmoking, not on a weightloss regime, no medications, no mental disease, no history of head trauma, and no eating disorders (Sujeta et al., 2016). Each participant performed baseline measurements after an overnight fast consisting of weight, BMI, electrocardiogram, near-infrared spectroscopy for brain activity, blood pressure, blood glucose, and the Brunel Mood Scale test (Sujeta et al., 2016). Cognitive function was tested using matching grid tasks, Manikin Task for spatial orientation, memory search tasks, mathematical testing, reaction time tests, and task switching (Sujeta et al., 2016). Motivation throughout the tests was measured by the 9-point Paas scale. Pearson correlation coefficients, Cohen’s effect size, and t-test were used to compare how fasting affected each of the tests (Sujeta et al., 2016).
Results
Weight (p=.003), blood glucose level (p=.012), heart rate (p=.044), and systolic blood pressure (p=.039) were significantly reduced with the fasted state (Sujeta et al., 2016). Resting brain activity was affected in showing a decrease in oxygenated hemoglobin at p=.040, but no significant change resulted from the fast in total hemoglobin or deoxygenated hemoglobin (Sujeta et al., 2016). In regards to the tests, reaction time and task switching were significantly decreased by p=0.49 and p=.004, respectively (Sujeta et al., 2016). The lack of oxygenated hemoglobin had effects on the mathematical test, task switching, and accuracy of the reaction time task. Mood was affected significantly in anger states, confusion, and fatigue. Hunger levels were positively correlated with fatigue and oppositely with vigor.
Discussion
Of the two portions of the brain examined in this study, the prefrontal-cortex and the hippocampus, it was found that the working memory, set shifting, and mental flexibility of the prefrontal-cortex were affected by the fast, whereas the spatial orientation tasks of the hippocampus were not affected (Sujeta et al., 2016). One noteworthy effect was in regards to the heart rate being affected and may be a result of the body producing ketone bodies as a survival technique (Sujeta et al., 2016). This study encountered limitations with being able to measure any changes in parasympathetic activity in the amateur weight lifters, however, previous studies found that there were risks to the parasympathetic system after a fasting state. This could be explained by the lack of amount of test subjects or the testing protocols. The study also found that the fast significantly decreased glucose which led to decreased oxygenated hemoglobin and decreased resting brain activity (Sujeta et al., 2016). As expected, the study found that the fast negatively affected mood, but what was a new find was that anger is associated with a decrease in parasympathetic activity, but an increase in sympathetic, which will lead to an increase in blood pressure (Sujeta et al., 2016). Some limitations to this study are that neurotransmitters were not able to be monitored and that these results cannot transcend into the general population or between men and women due to changes in how each gender and population handles stress.
Application
The first practical application this study attests to is said right in the first sentence when they discuss religious viewpoints for participating in fasting. Growing up in a diverse community, I have experience with sporting events and teammates who would still try to maintain their active lifestyles while being on extended fasts. This would ultimately result in decreased performance, mood, and reaction time—all things that can pose safety issues when in competition. Another area of concern is when people go to the gym who are trying to lose weight and decide to go fasted thinking that it will increase their weight loss rate, a proven fallacy which still remains prominent and as an area of discussion amongst fitness professional. This study is applicable because it shows that being fasted leads to decreased reaction time, task switching abilities, mood, and oxygenated hemoglobin.
References
Solianik, R., Sujeta, A., Terentjeviene, A., & Skurvydas, A. (2016). Effect of 48h fasting on autonomic function, brain activity, cognition, and mood in amateur weight lifters. BioMed Research International, 2016, 1-8. Retrieved from https://web-a-ebscohost-com.cucproxy.cuchicago.edu/ehost/pdfviewer/pdfviewer?vid=28&sid=367df459-c1d4-491c-852e-2a51afa98fb5%40sessionmgr4010
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