Name: Your Brain on Intermittent Fasting: More Cognitive Benefits From Eating Less Often?
Uploaded: 2026-03-05T03:26:54.000Z
Duration: 5 min 16 s
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We all know people fast for weight loss, but

researchers are looking at whether it can make our brains work better and longer.

Going long periods of time, sometimes even whole days with little to no food is a popular way to boost performance for some Silicon Valley types.

And how long do you have to go without eating?

Before we do that, it's important to know that fasting comes with certain risks and nobody should try it before talking to their doctor first.

With that said, let's talk about how long you have to fast to see any potential benefits.

The researchers I talked to said it was a minimum of 12 to 14 hours.

That has to do with how the body fuels itself.

Usually the body uses glucose as sugar as fuel, but

after about 12 hours of fasting, the body starts using ketones which come from fats.

Scientists think it's that that metabolic switch that starts a chain of events that leads to some of the potential brain related benefits of intermittent fasting.

Neuroscientists like Mark Mattson, who study the effects of intermittent fasting on animal brains, have found that it can improve focus, slow declines in brain health, and

improve cells ability to cope with their version of stress in people.

There's some preliminary evidence that it can help with mood too.

In his animal research, Mark looked at the hippocampus, which is a brain region that's important for learning and memory.

He found that during fasting, some neurons in the hippocampus which respond to glutamate, the brain's most important chemical messenger, are more active.

Those are the brain cells that help you learn and remember what's important.

If you're an animal in the wild, you're hungry, you haven't found anything to eat for a long time.

Those neural circuits involved in trying to figure out where to get the food better be active.

But then something really interesting happens.

After weeks of intermittent fasting, memory becomes more efficient.

That happens because a separate set of neurons quiets down the activity of some of those glutamate friendly neurons, specifically those that aren't involved in the task at hand.

Basically your brain becomes more efficient by turning down the noise and, and focusing in.

And I've noticed this personally, that I really function well in the morning when I haven't eaten anything.

Preliminary evidence from Courtney Peterson, another intermittent fasting expert I spoke to, suggests that there could be some mood related benefits.

We found that People reported greater energy levels, fewer feelings of depression, and

dejection in individuals who actually stuck with the program five days a week, every week.

Intermittent fasting may also help slow down declines in brain health, at least in older patients.

That's because fasting kicks into high gear, a process called autophagy, which literally means self eating.

it might help explain why the handful of studies that have found brain related benefits of intermittent fasting have found the strongest effects among older people.

One study in patients with mild cognitive impairment, which usually precedes Alzheimer's, found that intermittent fasting had benefits in keeping further mental decline at bay.

So you might be wondering, how are these things connected?

Well, think of autophagy as a cell's recycling system.

It helps keep your neurons, and by extension, your brain, free of toxic junk.

During this process, little Pac man style sacs engulf old proteins and mitochondria that aren't working properly and causing your cells stress.

Those proteins in mitochondria get chewed up and their components are used again.

As we grow older, though, our cells become more prone to being filled up with toxic proteins, in part because autophagy becomes less efficient.

This is all really interesting science, but intermittent fasting isn't for everyone.

I generally don't recommend it before your mid-20s.

Courtney also said you should avoid it if you're pregnant.

If you have diabetes, consult with your doctor.

And for those who work the night shift, scientists know even less about its effects on people.

One of the drawbacks to intermittent fasting is that food is social.

So people feel like they're missing out on life if they can't eat with their friends.

Plus, fasts that last whole days may not work as well long term because people get hungry or hangry.

I mean, chocolate and Cheetos sound really good right now.

Moving forward, Courtney told me that a big open question was which fasting schedules actually work?

And Mark is currently scanning people's brains to look for changes in brain activity and connectivity between brain areas.

In other words, he wants to replicate his animal studies in people.

If researchers are able to pin down the benefits and drawbacks of intermittent fasting more specifically, then people would be able to make more informed decisions about whether to try it or or not.