Healthy adults who fast stay sharp.

A meta-analysis led by Dr David Moreau pooled 71 studies from 1958 to 2025, covering 3,484 people across 222 cognitive tests, and found no meaningful difference between fasted and fed adults.

After about 12 hours without food the body shifts from glucose to ketones, keeping the brain fuelled.

Fasting can also trigger cellular clean-up and improve insulin sensitivity.

Three points matter locally.

Children and teens performed worse when they skipped meals, so breakfast still matters on school days.

Timing counts. Performance dipped later in the day for fasted people, so tougher tasks may land better in the morning.

Context counts too. Neutral tasks held steady or improved slightly, but food cues made hungry minds more distractible.

David Moreau, Associate Professor of Psychology - University of Auckland.

Coasties can try time-restricted eating with confidence if they’re healthy adults, plan key work earlier, and keep snack temptations out of sight.

Those with medical conditions should seek advice first, and anyone working late or around food may find fasting harder to sustain.

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