 Hey everyone, Dr. O here. In this lesson, we're going to cover the last big fasting myth, which is that fasting makes you tired and causes brain fog. We'll talk about what could actually do that, but people are terrified of fasting because they think it's going to sap all their energy and cause this brain fog that makes it so they basically can't function. But the reason this is a myth is all about norepinephrine. So norepinephrine is noradrenaline. It's related to epinephrine or adrenaline obviously. And norepinephrine increases, I'll show you a study that showed that it doubles when you're in the facet state. So norepinephrine is actually what increases mental focus and energy. This is the reason that when people are in serious emergency situations, they talk about how time slows down. That's actually because norepinephrine levels spike and it feels like time slows down because your brain is basically energized. Your brain is working in fast forward. So let's look at the study we mentioned it once before, but resting energy expenditure in short term starvation is increased as a result of an increase in serum norepinephrine. We talked about how norepinephrine actually causes your metabolic rate to go up 14% during a short term fast. But the norepinephrine levels do double. So why? Why does norepinephrine go up so much when you're in the middle of a fast? It actually goes up by increasing the amount that's being released and then how often it's being released. So why does it do this? So you actually have the mental clarity you need and the energy you need to go out and find food or not become food. So think about it. If our ancestors were starving because they couldn't find something to eat, would laying down and being exhausted and having brain fog actually have helped them find food or not become food? No. If our ancestors would have just laid down and died, we wouldn't be here. The boost in norepinephrine is what caused them to have a spike in energy, a spike in metabolic rate so they could go out and find the food they needed. So it's very important to understand that norepinephrine levels actually go through the roof when you're in the middle of a fast and it's designed to keep you from having brain fog and to keep you from being tired. So let's talk about the elephant in the room though. Why do some people feel tired and have brain fog when they try fasting or any other diet? Simply put, you are a food addict, a sugar addict, and you're going through withdrawals. I don't mean any offense by that. Some people argue that food addiction isn't a real addiction, but I think it's close enough if it isn't. So yes, you may feel tired and you may have brain fog if you go periods without eating when you have it in a long time. That's just because it takes time for your body to adapt. You're used to eating all of the time and maybe eating a lot of sugar and these types of things. So your body is used to these wild fluctuations in blood sugar. Blood sugar goes up, comes crashing down, so you need to eat something to bring it back up, bring it down, back up, down, up, down. So your body is used to this cycle. It takes time for your blood sugar to normalize, which is what will happen as you get used to a fast. I would say that fasting is a muscle. The more you use it, the better it functions. So your body has to get used to normalizing your blood glucose, not having these peaks and valleys, these rises and these crashes. Your body also has to get used to using fat as a fuel source. It's the same reason that when people go on ketogenic diets, it takes time to get used to it. It can take three to six weeks for your body to become completely fat adapted. So I'm not saying you have to suffer for three to six weeks when you're fasting, but I'm just saying early on, when you first start fasting or going on any diet, you probably will feel tired and have some brain fog, but it's not necessary and there's not a physiological reason for that. It's these types of things. If you can get your blood sugar normalized, your body gets used to burning fat for fuel, then you should actually experience the benefits of having this spike in norepinephrine, the benefits of more mental focus and more clarity, the benefits of an increased metabolic rate without the downsides. So I'm certainly not saying that you might not feel tired or have brain fog when you first go on any kind of diet, including a fasting protocol, but I want to explain that it is not a requirement and it is not necessary and it's not inherently anything to do with the fasting protocol. So this is why people swear by ketogenic diets and fasting because of how it enhances mental clarity. You can go back all the way to the time of Socrates when they used fasting to enhance mental clarity, not to lead to brain fog. So personal experience, I teach anatomy and physiology, microbiology, and nutrition for a living. I have an extremely mentally taxing job. I have to remember thousands of bits of information and I have to share it with students constantly on the fly. I teach all of my face-to-face classes completely fasted without any trouble because I actually find that when I'm in the classroom is the best time to be fasting because I'm too busy to think about food. And then just as another little aside, I recently gave a two-hour presentation on brain health and I didn't do this on purpose, but I actually gave a two-hour presentation on brain health tons of information there and it went really, really well, but I was five and a half days into a fast. This was actually the last extended fast that I did. I used to do some extended six-day fasts. The last one that I did, five and a half days in a fast, two-hour presentation on brain health, no notes, and I did great. So personal experience and scientific studies and all the people I've worked with show that no, fasting does not inherently make you tired or cause brain fog. So we have busted this myth as well. If you're having those kind of problems, then follow my program for how to prepare for fasts, how to ease into fasting, how to minimize these kind of problems, but it is not the fasting that's causing these issues. All right. I hope this helps. Have a wonderful day. Be blessed.