Welcome to the Dr. Gundry podcast, where Dr. Stephen Gundry shares his groundbreaking research from over 25 years of treating patients with diet and lifestyle changes alone.

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What happens if you water fast for 72 hours? The 72-hour fast, where the heck did this come from?

And why 72 hours?

Now, I'm not a huge fan of going without food for this long, for a couple of reasons.

Instead, as you probably know, I recommend time-restricted eating,

which is where you ideally reduce your eating window to about a six to eight

hour period. But we'll talk about that in just a little bit. Now here's the major problem with a

72 hour water fast. Most people will crash and burn.

Why?

Studies have shown that even if you are of normal weight, in other words, you're thin. 50% of you are metabolically inflexible.

Now, what does that mean?

Normally, your mitochondria that make ATP like to burn glucose, sugar for fuel. But if glucose runs out and isn't available, they can make a switch

to burning free fatty acids that are liberated from

fat cells to make energy. Now your brain unfortunately can't get free fatty acids because quite frankly

they're too big to get through the blood-brain barrier. Instead,

your brain will use ketones, which your liver will make if free fatty acids are available.

Now, it's a big if. Here's the problem. 50% of us, plain old normal weight people, can't make that switch.

92% of overweight people can't make that switch.

And 98% of obese people can't make that switch.

So what happens if you decide to just drink water for 72 hours?

You will exhaust your glucose supplies in about 8 to 12 hours.

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