Is Fasting Good for Your Gut Bacteria?

Gut bacteria play an essential role in regulating your mood, protecting your immune system, and getting the most nutrition out of your food—here's a simple way to give them a boost

The power of fasting and the benefits of good gut bacteria are two of the biggest breakthroughs to come out of health research in the past few years. Research has proven that combining these two health trends—fasting for gut health—might actually help make you healthier, fitter, and even happier.

Fasting may help protect your gut microbiome. And in turn, those bacteria could help protect your body while you're fasting, according to a 2016 study published in the Proceedings of the National Academy of Sciences. Scientists have known for a while now that both fasting and gut health can boost your immune system, protecting you from illness and helping you recover faster when you do get sick. But this new research shows that fasting flips a genetic switch that activates an anti-inflammatory response in your gut, protecting both you and your healthy gut bacteria.

The research was done on fruit flies—which are definitely not humans. But, the scientists said, flies express many of the same metabolism-related genes as humans do, giving important clues about how our own systems operate. And they found that flies that fasted and activated that brain-gut signal lived twice as long as their less fortunate counterparts. (

This doesn't mean that fasting for gut health will make you live twice as long (we wish it were that simple!) but it is more evidence of the good that fasting can do. More research is needed on actual humans before a definitive link is proven. Nonetheless, other studies have shown that in addition to benefiting our gut microbiome and protecting our immune systems, fasting also can improve mood, increase insulin sensitivity, aid in building muscle, increase your metabolism, and help you lose fat.

One of the best things about fasting for gut health is that, as far as health hacks go, this one is about as simple as it gets: Simply choose an amount of time (usually between 12 and 30 hours—sleeping counts!) to abstain from food. If you're interested in trying an intermittent fasting program, there are many methods to get you started, like the 5:2 Diet, Leangains, Eat Stop Eat, and the Dubrow Diet.

"I think fasting is a good strategy to lose weight without feeling deprived or suffering, as it allows you to have full meals, eating what you like, but overall you're still eating less," says Peter LePort, M.D., the medical director of the MemorialCare Center for Obesity at Orange Coast Memorial Medical Center in Fountain Valley, CA, adding that it's safe for most people to try.

Still, if you’re considering fasting for gut health and have any history with eating disorders or are currently dealing with a blood sugar-related conditions such as type 1 diabetes, you should steer clear and focus on boosting your gut health in other ways. (Ahem, probiotics…)

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