Study Reveals Short Fasts Do Not Impair Cognitive Functioning

Research published in the journal Psychological Bulletin indicates that short-term fasting, including skipping breakfast or following intermittent fasting, does not significantly impair cognitive abilities in healthy adults. This study, led by David Moreau, Ph.D., an associate professor of psychology at the University of Auckland, systematically examined the effects of fasting on mental performance among adults.

The research involved a comprehensive meta-analysis of 71 studies that compared cognitive performance in individuals who had recently eaten with those who were fasting. In total, the analysis included 3,484 participants, with most fasting periods being short-term, averaging around 12 hours in duration.

Fasting’s Impact on Cognitive Performance

The findings revealed no consistent evidence that short-term fasting adversely affected mental performance. “Our main finding was that there is generally no consistent evidence that short-term fasting impaired mental performance,” stated Moreau. Individuals who fasted exhibited cognitive performance levels comparable to those who had recently consumed food.

While the overall results were reassuring, the study did identify specific contexts where fasting could influence cognitive performance. Notably, tasks that involved food-related stimuli, such as viewing images of food or processing food-related language, showed modest declines in performance. Moreau noted, “Hungry individuals might experience distractions in contexts relevant to food, yet general cognitive function remains stable.”

Age Differences and Implications for Public Health

Age emerged as a significant factor in cognitive performance during fasting. Children, who were included in a small portion of the dataset, displayed more pronounced performance deficits compared to adults. “These findings echo previous studies highlighting the cognitive benefits of breakfast for younger individuals,” Moreau explained. The researchers suggest that pediatric populations may require special consideration regarding fasting practices due to their developing brains’ sensitivity to energy deficiency.

The implications of this research extend beyond the laboratory. Moreau emphasized the reassuring message that healthy adults need not worry about temporary fasting affecting their cognitive abilities. He stated, “Physiologically, fasting triggers important metabolic shifts. When glycogen stores are depleted, the body utilizes ketone bodies from fat tissue as an alternative energy source. Emerging evidence suggests that this reliance on ketones could confer health benefits and promote longevity.”

This research supports the viability of intermittent fasting as a health intervention for adults, while also highlighting the necessity of adjusting fasting practices for specific demographic groups, including children and individuals with medical conditions.

More information regarding this study can be found in the article titled “Acute Effects of Fasting on Cognitive Performance: A Systematic Review and Meta-Analysis,” authored by David Moreau and colleagues, published in March 2025.