Cognitive skills assessed in the studies included memory recall, decision-making, and response speed and accuracy. When these assessments were taken as a whole, short-term fasting (with a median duration of 12 hours) didn’t significantly change the scoring.

There were some nuances though.

The researchers found modest cognitive performance reductions in fasting intervals over 12 hours, and “noticeable declines” in children and teenagers (though kids only made up a small portion of the participants).

That suggests that young and developing brains might be more at risk from going without food for extended periods, and that for kids and teens, three regular meals a day matters a lot.

Interestingly, food-related tasks testing cognitive performance are where impacts showed up the most. It’s possible that very specific brain circuits do start to flag during fasting, though further studies will be required to know for sure.

“Performance deficits were often evident only in tasks involving food-related stimuli, such as looking at pictures of food or processing food-related words,” Moreau said.

“In contrast, performance on tasks using neutral content was largely unaffected.”

“Hunger might selectively divert cognitive resources or cause distraction only in food-relevant contexts, but general cognitive functioning remains largely stable.”

The researchers also found that individuals who were fasting tended to do worse in cognitive tests when they were carried out later in the day – perhaps hinting that going without food acts as a sort of amplifier to the natural dips in concentration that can come with our built-in circadian rhythms.

As well as helping some people to manage their weight, fasting has also been associated with other health benefits in scientific studies, including improvements in cardiovascular health and reductions in inflammation levels.