Transcription
Dr. Mindy here, and on this video, we are going to talk about the 48-hour fast.
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Okay, 48-hour fast. Here's what's really cool. When you break down fasting, you look at 15 hours is really helping us become metabolically flexible. 17 hours is helping our cells start to detox. 24 hours, we start resetting our gut. 36 hours, we start making our body more efficient at burning fat. And at 48 hours, we amp up our brain power.
So, I have four studies that I want to share with you guys. They all come at looking at the 48-hour fast in unique ways. But before I launch into those studies, I want you to realize that there are two major things that happen to us as we age.
One is that our dopamine receptor sites become less sensitive. So, just because you make dopamine doesn't mean that you're going to use that dopamine and you're going to experience dopamine in the same way. So, how this looks for you is it may look like you've been, you know, everything in your life looks fine, but you're just not as joyful as you used to be. Or things that used to excite you don't excite you as much anymore. And that could be because these dopamine receptor sites are not as sensitive. A little bit like insulin receptor sites that don't become as sensitive. Dopamine receptor sites can get blunted and it can not take in the dopamine molecules as easily. So, one of the changes you're going to see here is that this 48-hour fast starts to reensitize these dopamine receptor sites.
The second thing that you'll see in some of the studies I'm going to share with you is that when we have been under a tremendous amount of stress for a long period of time, and the longer we live on this planet, the more stress we're going to have, what ends up happening is that we start getting locked into our amygdala. Our amygdala is the midbrain. It is the fight-or-flight brain. So, as you age, as stress goes up, as you have more trauma, you need tools to start to help to get more blood flow, more activity to the prefrontal cortex. I talk about that a lot this week because the prefrontal cortex, when you're operating from this part of your brain, it quiets the anxiety fight-or-flight brain. And you're going to see that the 48-hour fast can start to help us with more cognition in the prefrontal cortex. So that's really cool, right? So these are the two principles I'm operating off as I go down these four studies.
Okay, first one was a study that they did where they took two groups of people and they said, "Okay, one can eat all day and the other we're going to restrict their calories by 70%." Now, they didn't do the eating window, fasting window, that routine. They just restricted by 70%. And all they were looking at was these dopamine receptor sites. And what they found is that in the people that they restricted calories from for 70% of their calories, that they increased increased the number of receptor sites. So, this isn't even making these receptor sites more sensitive. I'll show you that study in a moment. You actually got more dopamine receptor sites. So, think about it. Those of you that have been fasting a long time, how excited are you when all of a sudden you open up your eating window and you're like, "Hm, okay, I'm ready to go. Let me start eating." You get so much more joy out of your food because you literally have created more receptor sites that will pull the dopamine into the cells and activate joy in your brain. That's pretty cool.
Okay, second study was done. This was specifically done on a 48-hour fast on amateur weightlifters. And what they did is they found that after 48 hours, no, it was water, no calories. So there was nothing. It was just water for 48 hours. And they found that they had higher parasympathetic activity, which if you're familiar with the nervous system, your sympathetic nervous system is what is that fight-or-flight like go go go nervous system. And the parasympathetic is the rest and digest. So a 48-hour fast in these amateur weightlifters improved parasympathetic activity. So they chilled out. Okay. It also decreased resting, and this is part, this is important, resting frontal brain activities. So think about it for a second. How many times have you been sitting around and think, "I shouldn't be anxious. I should be doing something. Why can't I just sit here?" And you feel wound up. That's because at rest, your prefrontal cortex is constantly going. We need our prefrontal cortex to be able to solve problems, which is great, and to be able to to put see a goal and go after a goal. But when we're resting, we don't want it active. And so what they found in these weightlifters is at 48 hours, they started to see the prefrontal cortex, um, resting prefrontal cortex activity come down. Okay.
And then the third thing that I think is really interesting is they saw parts of the prefrontal cortex in these amateur weightlifters that became the cognitive functions improved, and specifically, this is so cool, specifically in mental flexibility. So, what does that mean? That means that they were able to go from task to task to task much easier and switch in and out of different learning styles. So, those of you that are studying, those of you that have jobs that require a lot of multitasking, this is where the 48-hour fast is going to help to condition your brain. Okay?
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Okay. Third study. This is also a really cool one. This study showed that as ketones went up, there was another neurochemical that went up which is called BDNF. So the more ketones you get, the more BDNF you get. And what they found is that BDNF alerts the neurons in the hippocampus and says, "Hey, we're going to make a metabolic shift here. We're going from glucose to ketones." And in that, we need you to start repairing. And so that's exactly what the brain does. The hippocampus is the part of the brain that's mood and memory. So this one was done on, they went over 24 hours. They didn't say how long, but they said it was an over 24-hour fast. So, I'm putting it in the 48-hour fast category. And they said that when the BDNF came on the scene, because ketones came on the scene, that these neurons in the mood and memory part of our brains started to regenerate. They started to create new neurons, and the brain was more able to learn. The brain was more alert because of that metabolic switch. How cool is that?
Okay. And then the last one, this was also a 24-hour plus one. So again, they didn't, they didn't say hardcore 24 or hardcore 48. So I'm going to put it in the 48 because I want your brain to be working at its best. So they found that they passed 24 hours, they started to see an increase in dopamine release in the brain. So you got more dopamine coming out. If we go back to that first study, you've got more receptor sites. If we go to the third study, you've got more of these neural pathways carrying dopamine, and now we're seeing you're going to get, like I said, more release. The other thing, and the last thing I'm going to tell you, if you're not completely convinced, is that what they found is that these neurons, these new neurons were more excitable. So the effect that a 48-hour fast can have on dopamine, on BDNF, on the hippocampus for mood and memory, on the prefrontal cortex. Study after study after study is showing that the longer you fast, the more the benefits turn to the brain. Okay?
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So if you think about it, all the humans that emerged out of that time have the gene that allows us to go without food. And that gene, they believe, is in all of us.