Theme Food III: Short-term fasting doesn’t hurt brain power

My dad always stressed the importance of eating breakfast before school, insisting that an empty stomach would “dull my brain and make learning much harder.” I dutifully ate my oats—but was he right?

There are two main theories about how fasting could affect the brain. One hypothesis suggests that fasting drains the brain's cognitive resources, making it harder to focus on tasks unrelated to hunger. Hunger becomes a distraction, causing people to make poorer decisions or struggle with complex tasks. On the other hand, some research shows that hunger may sharpen decision-making.

This study specifically examines the effects of short-term fasting, looking at whether a brief period without food impacts cognitive ability.

The study
Researchers conducted an experiment with 245 participants to assess if fasting, induced by either 3-hour or 12-hour periods without food, has any measurable impact on cognitive performance.

The study also looked at potential differences in how fasting affects individuals based on characteristics such as Body Mass Index, race, and their relationships with food.

The study used a test that measured abstract reasoning. That means checking how well someone can think about ideas and concepts that aren’t based on real, physical things. It looks at how well they can solve problems, spot patterns, and understand complex ideas. This helps to see how well their brain is working in general.

Results showed no significant decline in cognitive ability after fasting for either 3 hours or 12 hours, suggesting that short-term fasting does not impair short-term cognitive function. The experiment also found little variation in how fasting affected individuals based on factors like body weight or race. 

Fasting - and how well we think.
Previous research has shown that longer periods of fasting or chronic food scarcity can negatively affect cognitive functions such as attention, memory, and problem-solving.

The study’s findings challenge the assumption that short-term food deprivation leads to a noticeable drop in cognitive ability.

This study indicates that in a safe environment with no general food scarcity, it does not seem to hinder basic cognitive tasks. Tasks that require fluid intelligence, such as the ability to think quickly, solve new problems, and adapt to unfamiliar situations

Hunger may very well impact decision-making. But the lack of a significant cognitive penalty after short fasting suggests that the context, timing, and duration of food deprivation may be crucial factors.

To oat or not to oat - that is the question
The study contributes to ongoing research on intermittent fasting and its effects on health and cognitive function.

While short-term fasting has been linked to various health benefits, including weight loss and cholesterol reduction, this study provides evidence that it does not significantly impair cognitive ability in the short run.

Given the growing popularity of intermittent fasting, especially for health or religious reasons, these findings suggest that fasting for up to 12 hours is unlikely to have a substantial immediate cognitive cost.

(But fasting may impact your brain when you age.)

About the scientific paper:

First author: Austin Landini, USA
Published in: PLoS One. November 2024. 
Link to paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0312811