Short-Term Fasting Found to Preserve Cognitive Function in Adults

Research published in the journal Psychological Bulletin indicates that short-term fasting does not impair cognitive abilities in healthy adults. The study, led by David Moreau, Ph.D., an associate professor of psychology at the University of Auckland, analyzed a total of 71 studies to assess the impact of fasting on cognitive performance.

The analysis included data from 3,484 participants and examined various cognitive functions, such as memory recall, decision-making, and response speed. Most fasting periods examined had a median duration of 12 hours, focusing mostly on the effects of skipping meals, including breakfast and intermittent fasting.

Key Findings on Fasting and Cognitive Performance

The primary conclusion drawn from the research is that there is no consistent evidence showing that short-term fasting negatively affects mental performance. Moreau stated, “Individuals who fasted performed remarkably similarly to those who had recently eaten, suggesting cognitive function remains stable in the absence of food intake.”

While the overall findings were reassuring, the study did observe some subtleties. There were modest reductions in cognitive performance for fasting durations exceeding 12 hours and noted that children, who were a small part of the dataset, experienced greater performance deficits compared to adults. Moreau expressed surprise at these results, noting they challenge the common belief that fasting inherently compromises cognitive abilities.

Contextual Factors and Implications for Different Age Groups

The study revealed intriguing insights about the context of fasting. Performance deficits were more pronounced in tasks involving food-related stimuli, such as images or words associated with food. In contrast, tasks using neutral content showed little to no impact. Moreau explained that hunger may only divert cognitive resources when related to food, but overall cognitive functioning remains stable under fasting conditions.

Another significant finding was the marked difference in cognitive performance between age groups. Moreau highlighted that children demonstrated noticeable declines while fasting, reinforcing earlier studies that point to the cognitive benefits of breakfast for younger individuals. He advised that pediatric populations may require special consideration when evaluating fasting interventions, suggesting that their developing brains are more vulnerable to energy deficiencies.

The implications of this research extend beyond individual dietary choices to public health recommendations and fasting practices. Moreau emphasized that the key takeaway is reassurance for healthy adults: “Cognitive performance remains stable during short-term fasting, suggesting that most healthy adults need not worry about temporary fasting affecting their mental sharpness or ability to perform daily tasks.”

Physiologically, fasting induces significant metabolic changes. When glycogen stores are depleted, the body turns to ketone bodies from fat tissue as an alternative energy source. Emerging evidence indicates that this shift may offer health benefits, help regulate hormonal systems, and activate cellular repair processes linked to longevity.

The findings support the viability of intermittent fasting as a health intervention for adults, while also underscoring the necessity of customizing fasting practices for specific groups, including children and those with medical conditions.

For further details, refer to the study: Moreau, D., et al. (2025). Acute Effects of Fasting on Cognitive Performance: A Systematic Review and Meta-Analysis, Psychological Bulletin. DOI: 10.1037/bul0000492.