The Powerful Benefits of Fasting: Understanding the Science behind the Human Drive to Eat

In this video, the speaker discusses the health benefits of intermittent fasting and the importance of finding a balance between eating and fasting. They explain that human diseases, such as cardiovascular disease, diabetes, high blood pressure, and metabolic syndrome, can be attributed to the lack of balance in our eating habits. The video breaks down the physiological processes that occur during fasting, including the transition from using carbohydrates to fat for energy and the activation of autophagy, a recycling process in the body. The speaker also addresses common misconceptions about breakfast and hunger, and provides insights into exercising during fasting. Overall, they emphasize the potential benefits of fasting for disease prevention and overall health.

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Key Insights:

  • Most human diseases today stem from an imbalance between eating and fasting.
  • Eating food provides energy, while fasting allows the body to use stored fat for energy.
  • Consistently eating without periods of fasting congests the body and contributes to diseases like cardiovascular disease, diabetes, and high blood pressure.
  • Humans have four hormones to raise blood sugar but only one to lower it, as historically it has been more important to have a mechanism to raise blood sugar.
  • Unstable blood sugar is caused by frequent eating and reliance on carbohydrates, training the body to expect food and depend on frequent meals.
  • Intermittent fasting can lead to stable blood sugar, increased fat burning, and the activation of autophagy, a process of recycling and renewing cells.
  • Extended fasting of 24-72 hours leads to increased ketone production, growth hormone release, and immune system benefits.
  • Exercise during fasting should be limited to low-intensity aerobic activities that don’t require carbohydrates.
  • Fasting can provide benefits for disease prevention, immune health, brain function, and chemotherapy support.
  • People should gradually ease into fasting and pay attention to their body’s signals and supplement with minerals if necessary.


Hello Health Champions. Why is it that we, as humans, have such a powerful drive to eat food and yet scientists are finding more and more health benefits we get from skipping a few meals. We can go so far, in fact, to say that most of human disease today come from the fact that we cannot find a natural balance between how much we eat and how much we expend, the balance between eating and fasting. But why is it so difficult for us to find that balance? Well, let’s look at the basics here.

You eat some food, you use that food to generate energy. And if you’re lucky enough to eat a little bit more food than you need in the next few hours, then you can store some of it as body fat. And then when you don’t eat for a while, and you’re forced to fast or choose to fast, now you can start using some of that stored fat to make energy. An analogy would be that you have a pantry and you put things in your pantry for the sole purpose of sometimes emptying the pantry. The purpose of a pantry is so you don’t have to run to the store every time you need something every few hours. But it wouldn’t make sense to put something in the pantry if you’re never going to take anything out. And it’s the same thing with the body. Why would you ever store something if you didn’t plan to fast? If you only put things in and never take anything out, then why would you store it? Why do we even have that function?

Right, this provides rotation. If we put in and we take out, that rotates it. But if we don’t rotate it, now we have a stagnant situation. Now the stuff in the pantry gets old. You can also think of it as a pond. If you only have water flowing into a pond and nothing flowing out, it’s like a closed-off area. Now that water is going to get super nasty. It’s going to get infested. It’s going to get congested, polluted. You’re going to have all sorts of parasites and mosquito farms and things in there. And the only reason this happens in the body is that we eat too frequently. When we eat too frequently and we never fast, we’re only putting things in the pantry, we’re never taking anything out, and that creates an imbalance. And not just any little imbalance, but the fact that we can’t find a balance between eating and fasting accounts for the majority of all human disease, probably 90 plus percent. All of the diseases of cardiovascular disease, diabetes, high blood pressure, metabolic syndrome. It is all because we never take anything out, we’re congesting the body.

So the next question, of course, is why do we eat so frequently? Some say the reason is the USDA guidelines because they tell us to eat three square meals and then snacks in between so you never have a drop in blood sugar, you top it off every couple hours. Well, I don’t think that’s the whole truth because I don’t know many people, if anybody, who will do something just because the government says so. But it certainly doesn’t help when we don’t know what we’re supposed to do. The real reason is unstable blood sugar, unstable glucose that we are training the body through our food choices and our lifestyles. We have trained the body into relying on it and depending on these frequent meals.

A very interesting fact to me is that we have four hormones to raise blood sugar, but we only have one to lower blood sugar, and that’s insulin. And that has to be because for most of human existence, it’s been more important to have a mechanism to raise blood sugar than to lower it. So we have these four hormones: glucagon, cortisol, adrenaline, and human growth hormone. And they’re all involved in raising blood sugar. So it used to probably look something like this for most of human existence, that we would eat a meal, we release a little insulin to bring the glucose down, and then we have these four hormones to bring it back up to where it needs to be and then to maintain it. To maintain a rock-solid blood glucose level for all the energy demands of the body so they don’t fluctuate just because we don’t eat for a little while. In other words, we’re much, much better at raising blood sugar. We are better equipped at raising blood sugar than we are at lowering it because that’s what it’s been like, that’s what there’s been the greatest demand for most of the time until the last 50 to 100 years. That’s where everything has changed. We have started eating more grains, more processed foods, more sugar, and more frequent meals, and these all go hand in hand because they train the body into expecting this.

So we eat a meal that raises blood sugar a lot. Now we need insulin to bring it back down. But then we eat so frequently and we eat garbage food and sugar and processed foods that don’t last us. So then we get a low blood sugar and we eat again to bring it up. We don’t rely on this mechanism to bring up the blood sugar and stabilize it. So it never gets stable. If we eat to bring it up, insulin brings it down and we eat again and it brings it down, and we eat again. So it’s this roller coaster.

So in other words, for as long as humans have been around, we’ve had this beautiful system of stable energy supply based on these four hormones. We have this sophisticated machinery in place. But then the last 50 to 100 years, we’ve thrown that out the window and we’ve replaced it with raising blood sugar, sort of artificially, through just eating all the time. And by doing that, we have trained the body to expect the food and to depend on these frequent meals. It doesn’t know how to do it without it anymore. So we have to retrain it by reducing the frequency of meals.

So let’s take a look at what happens if we go a little bit longer without. So eight hours without food, that’s the longest a lot of people have gone because that’s how long they sleep. During that time, your body is going to regulate glucose with these four hormones we talked about: glucagon, cortisol, human growth hormone, and adrenaline. And when you’re sleeping, you’re supposed to have sort of a low energy level, a low arousal level. But then when your body gets ready to wake up and you start your day, then you need a little arousal. So this is what these hormones provide. They raise your glucose and they arouse you so you’re ready for the day.

And eight hours in, you’re using a mix of glycogen and fat. And glycogen is your carbohydrate storage, mostly in the liver but also in the muscles. And that’s how your body stores carbohydrate. It can only store a little bit, about enough for a day. And depending on how you eat, you’re going to use a mix of these carbohydrates and fat. If you eat more carbohydrates, the mix is going to be more carbs. If you eat more fat, you’ve already taught your body a little bit about how to use fat instead of carbohydrate. But there will always be a balance there.

And what about hunger? Well, at this point, most people aren’t even hungry. Most people are not hungry when they wake up in the morning. But they eat because they’re taught to eat, and they think, „Well, if I don’t eat, I’ll probably be hungry in a few hours.“ And they say that breakfast is the most important meal, and everyone knows you can’t send your kids off to school because they get all F’s, they fail in school if you don’t feed them. So we have all these misconceptions, all these myths and misinformation about what’s going to happen. And we mostly eat out of habit and fear of what will happen if we don’t.

And if you don’t have that breakfast, not much is going to happen at all. Your body is going to increase glucagon and cortisol a little bit. It’s going to regulate blood glucose that way. It’s going to continue using glycogen and fat for energy. But it’s going to start shifting. It’s going to start transitioning from carbohydrate to more fat. It’s a slow, gradual process. And it’s going to depend on what you normally eat. If you have a high carb diet, then you’ve trained the body to depend on carbs. So the transition to fat is going to be slower, whereas if you’re on a low carb diet and you’ve been eating more fat, then it already sort of has some momentum. It already knows how to go over to use more fat.

After 18 hours, your glucose is starting to run down a little bit. Carbohydrates become a little scarce in your body, so your body starts making glucose from other things. That’s called gluconeogenesis. And at the same time, we continue the shift away from glycogen to fat. Your body is sensing that we’re starting to get down to the bottom of that carbohydrate, that glycogen barrel. And if we don’t have a lot of it, now we need to get better and better at using the fat. You probably won’t run completely out of glycogen. A lot of people say you will empty the tanks, but your body wants to have some glycogen as an emergency reserve just in case you get chased by something and you need to make an emergency sprint for a couple of minutes. That’s where you need just a little bit of glycogen. But more and more of your energy is starting to come from fat. And around this time, you have something called autophagy kick in. Autophagy means self-eating, and that sounds pretty drastic, but really what it’s about is upregulating recycling. So if you don’t put any more food resources into your body, then the resources that are already in the body become more precious. As you have cells die off, you have some debris, you have some virus, you have some bacteria, you have some dead blood cells, all of those materials, all that debris becomes resources. They become more precious, your body can use them. So it gets better and better at recycling that stuff. And that mechanism is one of the few things that can clean up inside the nervous system. So if you had a concussion or if you have brain inflammation or brain fog from poor lifestyle habits, autophagy is one of the few things that can start really cleaning up. But if you never go 18 hours without food, then you will never really experience autophagy.

Around this time, you also start seeing some higher levels of ketones. If you’re on a high carbohydrate diet to start with, it’ll probably take a little bit longer before you have any measurable amount of ketones. But if you’re low carb, this is where your ketones start increasing. And ketones are very interesting. You’ve heard of the ketogenic diet. So ketones are a byproduct of fat, and it’s something that the body makes as an alternative fuel source for the brain. Some people will tell you that the brain uses only glucose, that 100% of the energy for the brain is glucose, and that’s why you should eat a bunch of sugar. But that’s not true. The brain uses a mix of glucose and ketones. And if you’re fasting long enough, about 75% of the energy supply will come from ketones.

You will also see some increases in two super important hormones if you’re interested in brain health: human growth hormone and brain-derived neurotrophic factor. They’re two hormones that are like miracle growth for your brain. They’re necessary to make new connections, to maintain the vitality and health of brain cells, but also to make new connections. And that is how we learn something. As you process new information and you organize it, you have to make new connections to organize that. And with learning, if you fast and increase these hormones, you will find that you will learn better and you have better focus. And that makes a lot of sense because if you’re not eating, your body is probably going to start looking for food. And if you don’t have food, you need to get better, you need to get more innovative to pursue it and you need to stay focused so that you can execute and follow through.

And there will also be some immune benefits at this point. Your glucose will start dropping, which is one way, but also through this autophagy, you’ll start recycling more of the virus and the bacteria because they consist of proteins and cell components that your body can actually use for other things.

After 24 hours without eating, now things really start happening and your level, the depth, the degree of autophagy is going to keep increasing. If you have some blood strips, some ketone strips, and you measure your level of ketones, you will start finding that you’re now in the zone, most likely, of nutritional ketosis, somewhere between 0.5 and 1.5 millimoles. The glycogen by now is mostly gone. Like I said, the body will probably reserve a little bit, but it’s not going to depend on carbohydrate for energy. You’re going to be almost entirely burning fat. And you’re going to kick in more of the gluconeogenesis that I mentioned before, and the body makes glucose from other things. And what are those things? They’re primarily glycerol, which is about 5% of any fat molecule, a triglyceride. The backbone of that fat molecule is called glycerol. So 5% of the energy in fat actually can be converted to glucose. So even if you’re eating pure fat, about 5% of that energy is available for glucose. It will also convert waste protein, so these cell debris and virus bacteria, as well as the circulating pool, you don’t have all of your protein in muscles, you have some circulating at all times that’s sort of in transit. These are the things that your body uses to make new glucose when you need it because your brain still needs about 25% of its energy from glucose.

You also will increase your human growth hormone. You’ll really start kicking in now. And why is that important? Because if you need glucose and protein is one of the sources, you don’t want that protein to come from the muscles. And the human growth hormone spares the muscles and makes sure that muscles will be only as a very, very last resort when you’re near death, when you’ve gone weeks or months without food. That’s when you’re going to start using some of that muscle.

And what about hunger? Well, if you’ve never gone long without food, you’re probably going to be really hungry by now. But also understand that hunger is just a feeling. It’s not anything dangerous. It’s just a body sensation. Most of that body sensation is a habit. You’ve trained your body to expect food, so your body is going to create that hunger sensation at certain intervals. But if you ignore it, then not much is going to happen. It’s going to come and go. If you drink a glass of water and wait 10 minutes, it’s going to go away for a few more hours. So it’s not a big deal. And the better you get at intermittent fasting, you don’t have to go super long all the time. But if you teach your body that food doesn’t have to come every two hours, then that hunger becomes less and less important, and it’s not going to come calling as often.

48 hours into the fast, now you’ve gone two days without food, and you still want to drink plenty of water and you want to supplement with some minerals because you will lose additional minerals during a fast. Now your levels of human growth hormone are going to be up about 500% from their base level, five-fold increase. Your levels of brain-derived neurotrophic factor are going to be at similar levels. Your levels of ketones will now be into a more therapeutic level, like nutritional ketosis like we talked about. That’s more of a maintenance level. Now you’re stepping it up. Between 1.5 and 3 is where you start getting some really therapeutic benefits. Your levels of autophagy will keep increasing. And now, even though your insulin is dropping as long as you don’t eat from the moment that your body has processed through the food a few hours after a meal and you don’t eat, now your insulin will keep dropping. But once you go about 48 hours or longer, now you can really make a dent in that insulin. If you have stubborn insulin, very stubborn insulin resistance, then that insulin tends to kind of get on the plateau. But now, after 48 hours, that’s where you can really sort of force through that plateau and make a difference. And at this point, you are probably deriving about 95% of your energy from fat. Most of the other 5% come from the glycerol in the fat backbone, the triglycerides.

A lot of people will ask, well, what about exercise? Can you exercise when you’re fasting? Is it dangerous? What are you supposed to do? What kind of exercise? And yes, you can exercise as long as you don’t do any exercise that requires carbohydrates. You don’t want to do anything that looks like an emergency. So if you do purely aerobic exercise, if you go for a walk, if you keep your heart rate under 120, no huffing and puffing, now you’re staying in pure fat metabolism, now you’re enhancing the growth hormone, the autophagy, the ketones. You’re accentuating all of that without really creating stress or a hazard for the body because you stay in fat metabolism. But you don’t want to do any kind of high-intensity stuff because you don’t have the carbohydrate reserves for even short bursts. If you did, then you probably wouldn’t feel so good, you’d get very exhausted, and there’s a chance that you’ll be using up some muscle protein to make glucose.

And as far as hunger, it seems like you’d be almost dying at this point if you’re not used to this, if you’ve never done this before. But it turns out most people will tell you that the second day, the beginning of the second day is worse, that if you could just make it through the second day to like the second half of the second day, then things get easier. It’s like I said, the hunger is just a habit. It’s a habitual signal. If you ignore it long enough, then it goes away. And it actually gets easier.

And what happens if you don’t eat for three days? Well, 72 hours into it, all the same processes continue, but at a deeper level. So you’re getting more profound benefits from autophagy. You’re getting some deeper levels of disease reversals. So type 2 diabetes and cardiovascular disease and high blood pressure and even cancer. You’re starting to actually reverse those in many cases. There’s a lot of cancers, certain types of cancers that they’ve shown you can shrink tumors. And a lot of researchers are pointing out that you can probably reduce your overall risk of cancer by doing a three-day fast a couple of times a year. Also, around this time, we get hematopoiesis, stem cell regeneration and rejuvenation. So stem cells are your baby cells. They’re the cells that are born to become new cells in your body. And they’re not differentiated. They’re baby cells that can become different things in your body. But these particular ones, when they say hema something, that means blood cells. And when you’re making more of them and you’re rejuvenating, then you’re making more white blood cells, you’re strengthening your immune system, and cancer is primarily an immune problem. So that’s part of how you can fight off and reduce the risk of cancer. But you’re also improving your overall immunity toward your everyday virus and bacteria. And they have also found that this level of fasting provides very, very strong protection against chemotherapy. So there’s a reduction in the nausea and vomiting and hair loss and all of the harsh side effects from chemotherapy are reduced by fasting. Your body gets better at defending itself against the toxins which chemotherapy is.

Let me just point out that I think most people should go into this gradually. But if you decide to do 72 hours straight off the bat, the main thing that you want to figure out is how do you feel? You don’t want to push through if you’re nauseous, if you’re light-headed, if you’re not feeling well, then don’t continue. But as long as you’re feeling well, you are doing okay. It is not hazardous to your body to do this, especially if you make sure that you supplement with some minerals. If you’re on a low carb diet, you’re going to be losing some minerals, and it’s a good idea to supplement. But if you’re doing this level of fasting, then it’s an absolute necessity. You need to get some salt, some sodium, and some potassium into your body. If you enjoyed this video, you’re going to love that one. And if you truly want to master health by understanding how the body really works, make sure you subscribe, hit that bell, and turn on all the notifications so you never miss a life-saving video.