Introduction: Water fasting has been practiced for centuries for its purported health benefits, including weight loss and improved cognitive function. While the benefits of water fasting on physical health have been well-documented, its effects on cognitive function are less clear. The purpose of this systematic review is to evaluate the current evidence on the effects of water fasting on cognitive function.
Methods: A systematic search of electronic databases (PubMed, Web of Science, and Scopus) was conducted to identify relevant studies published up to September 2021. Studies that investigated the effects of water fasting on cognitive function in humans were included. Data were extracted and analyzed using a narrative synthesis approach.
Results: A total of six studies met the inclusion criteria. The studies varied in design, sample size, and fasting duration. Three studies reported improvements in cognitive function after water fasting, including improvements in attention, memory, and executive function. Two studies reported no significant changes in cognitive function after water fasting. One study reported a decline in cognitive function during the fast but improvements after refeeding.
Conclusion: The evidence on the effects of water fasting on cognitive function is limited and inconsistent. While some studies suggest that water fasting may improve cognitive function, others do not support this claim. Further research is needed to better understand the effects of water fasting on cognitive function and to determine optimal fasting durations and protocols to maximize potential benefits.
Implications: Given the limited and inconsistent evidence, it is not yet clear whether water fasting is an effective intervention for improving cognitive function. Individuals considering water fasting should be aware of the potential risks and should consult with a healthcare professional before beginning a fasting regimen. Further research is needed to clarify the potential cognitive benefits of water fasting and to identify the optimal fasting protocol for achieving these benefits.