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Analysis and Health

Does intermittent fasting improve gut health? Why it’s hard to say

While intermittent fasting may be growing in popularity, relatively little is known about how it impacts our gut microbiome – for better or for worse

By Grace Wade

9 May 2025

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

How does intermittent fasting change the gut microbiome?

Oliver Leedham/Alamy Stock Photo

There is evidence that intermittent fasting alters the gut microbiome, and while this is often believed to improve gut health, some studies are now raising doubts about whether that is always the case.

The idea behind intermittent fasting is relatively straightforward: instead of focusing on what you eat, you focus on when, cycling between periods of fasting and eating. The most popular approach limits all meals and snacks to the same 8-hour window each day.

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