Fasting is a practice that’s recently become quite trendy. There’s a more nuanced relationship when it comes to mental performance. David Moreau, an associate professor of psychology at the University of Auckland, Waipapa Taumata Rau, and colleagues conducted an exhaustive meta-analysis. These initial findings were promising, but they showed that fasting is not a one-size-fits-all approach. This research, which spans nearly seven decades from 1958 to 2025, explores how fasting affects cognitive functions and highlights significant variables such as age and timing.
The meta-analysis synthesized the findings of 63 peer-reviewed articles, including 71 independent studies with a total of 3,484 subjects. From these studies, we counted 222 distinct cognitive performance outcomes. This thorough analysis provides a rich basis for exploring the complexities of fasting and its impacts on cognition.
Fasting and Cognitive Performance
The findings reveal that fasting can affect mental performance, but the results are nuanced. Participants performed comparably on cognitive tests assessing attention, memory, and executive function, regardless of whether they had eaten recently or not. This suggests that, for some individuals, fasting may not significantly impair cognitive functions.
What we found was that the timing of fasting is an important factor that determines the cognitive benefits versus adverse effects. Studies show that compared to those who are non-fasted, performance in fasted participants is lower when testing is done later in the day. This decline can be associated with natural dips in circadian rhythms that drastically affect alertness and attentiveness. Therefore, the effectiveness of fasting on mental performance may depend on when one chooses to fast.
Age also emerges as a key factor in determining how fasting impacts cognition. Older individuals may experience different effects compared to younger participants, indicating that the relationship between fasting and cognitive performance is not uniform across demographics.
Health Benefits of Fasting
Aside from its cognitive performance improvements, fasting brings other positive health effects that would affect mental health. One notable advantage is improved insulin sensitivity. This improvement allows the body to better regulate blood sugar levels. In doing so, it dramatically decreases the risk of developing serious conditions such as type 2 diabetes.
Beyond the short-term, fasting has been linked with long-term benefits, such as aiding in weight management and promoting metabolic health. These reasons are creating a deepening argument for the wellness advantages of fasting. It can tremendously impact your overall physical wellbeing. As people plan to incorporate fasting into their lives, knowing these health benefits can make all the difference.
Individual Variability in Fasting Responses
This new paper adds to those findings by highlighting that fasting is not all-inclusive. That whole individual component is affected by a whole variety of different factors, age, timing, and personal health conditions. For example, though one person might report improved mental clarity during a fasting window, another might feel more tired or less able to focus and think critically.
This variability reinforces the need for personalized approaches to fasting. What is crucial, though, is that people pay attention to their own bodies and see how fasting affects their cognitive function. Asking your health care providers for advice can help you figure out what’s best for your life and situation.
