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Hello, everyone! I’m Dr. Trish Murray. Welcome to Discover Health Podcast. Today I’m so excited to be talking about fasting and your health with Dr. William Hsu. Doctor, welcome to the show!

Thank you, Dr. Murray. What an excitement to be on your show!

Yeah! It’s a joy to have you. So, Dr. Hsu, let me read your bio for folks so that they can get a sense of your background, and then we’ll get right into this whole concept of fasting and your health.

So, Dr. William Hsu. After twenty years of a distinguished career as an endocrinologist at Harvard’s Joslin Diabetes Center, Dr. William Hsu joined L-Nutra in 2019 as Chief Medical Officer. In his role, Dr. Hsu leads the clinical development effort at L-Nutra, he oversees the medical affairs department, and advances the education and adoption of fasting and the Fasting Mimicking Diet as an innovative tool to extend human health span.

Among his prior roles, he served as Vice President of Joslin Diabetes Center, a teaching affiliate of Harvard Medical School, responsible for its international education and health care advisory programs. He served on multiple national-level professional committees including the American Diabetes Association, setting national standards of medical care in diabetes. His previous research interests focused on the pathophysiology of diabetes and the application of digital technology in chronic care.

Dr. Hsu went to Cornell University for college and received his medical degree from Mount Sinai School of Medicine. He completed his internal medicine residency training at Yale School of Medicine and completed his fellowship training in Endocrinology and Metabolism at Harvard Medical School. He was Assistant Professor of Medicine at Harvard Medical School.

That’s a pretty impressive resume there, sir!

A little bit too long there.

Oh, that’s okay. That’s awesome! So, what people really want to hear though, Dr. Hsu, is what brought you to…what’s your story and how did you come to be of service the way you are now?

Well, that’s a really good challenge. All of my professional life I’ve always thought about like how do we continue to expand our impact, right? So, at first, I found it in the clinical care. Once you close the door one-on-one with your patient, you’re making impact one at a time. Then I say, “Well, you know we’ve got to go into research because that’s where the frontier of medicine is.”

So, I did about ten to fifteen years of that, and then I realized, you know, physicians they’re too busy to read original research papers. So, I say, “I got to get involved with associations because once you get into the associations, you help to set national guidelines. Then people could just follow the guidelines without reading original articles, right?”

And so, that’s what I did. Then little did I find out that many of the clinicians are too busy to follow guidelines. It’s too difficult, you know. It’s just, I mean you can. write all the guidelines you want, but it’s like, Okay. I’m going to practice the medicine the way I want to practice the medicine. So, I thought that I should probably get into building systems and that’s where I was really fortunate enough. At Joslin we had as many at one time almost, as I recall, 37 different Joslin affiliates around the country. I participated in really setting the programs and trainings and then took on the role of international programs where we helped to build hospitals, advise ministries health. So, we trained and built systems for practitioners to practice it. I thought, wow that’s pretty impactful. Why, there’s a global impact!

That was maybe five years ago when there was a huge revolution on digital health, and I said, “Look, I could build all the systems I want, but how do patients receive care in between their visits?” They’re on their own. I thought digital health really was the frontier that would allow us to extend the clinical care. So, I participated in research with MIT, and we came up with a way to initiate and adjust insulin doses all from the comfort of patients’ homes without ever going to step into the clinic. That was such a pioneering concept, but now with COVID, everybody and everything is done by telemedicine, right?


It was great. I mean, that was a great journey. Then one day my friend, one of my friends, challenged me. They said, “Well, you know what, you think you’ve done it all, but in fact you haven’t because if you can come up with a new product, a product, a drug, a medicine, an approach, that product can help hundreds of millions of people.” Think about that. They say, “You ought to look at this company and with this technology called the fasting mimicking technology.” I’m like, “Well, say that again.” “Fasting mimicking technology or the fasting mimicking diet?” I say, “Well, what is that?”

I think you know the rest is history. So, that’s where I am. Now I’m leading clinical development at a nutri-tech company, much like a biotech company where we’re really using the rigor of biotechnology to try to bring nutrition into sort of the mainstream of medicine. So, that’s been the focus of my effort in the last two years.

Like I said before, that’s just so interesting. Some of the things I heard you say, first of all, the listeners love to hear this stuff. I mean, you know, that’s what we all really want to know is what’s somebody’s story. What brought you to where you are? So, thank you for sharing all of that. It shows us kind of how you led to where you are today.

What intrigued me about what you said is, first of all, how busy doctors are but also how busy patients are and the idea of how do we really help people, give them the tools that are going to make them take notice and take the time to say, “Well, wait a minute this, is really going to make a difference in my life, so I really want to know what this is.”

With that being said, let’s talk a bit about fasting and your health. Can you explain, first of all, let’s talk with folks about what’s the connection between nutrition, longevity, and fasting. People have heard of it. I think they have an idea of what fasting is and all, but how does it connect to our health?

Yeah, so you think about like there are many behaviors in our lives that are so commonplace, but we forget to see sort of the insights. For example, activities. You know, we have this special name called exercise, but when in fact all throughout history of any organisms, animals or humans, we’ve always been focused on moving about because that’s how we hunt. This is how we gather; this is how we are able to feed ourselves. So now we have this special name called exercise where it is supposedly so good for you. Of course, because this is part of the mechanism how we have adapted to the environments for however millions of years we believe we have existed. Think about that.

Fasting is just like that, right? If you think about fasting, it’s a new term but it’s actually been practiced in every organism, every animal in the history of humanity, every religion, every people group in the world, right? It’s always part of someone’s tradition. So, why is that? A lot of people think about it as an interruption to feeding because like, Ah! I can’t eat today. I’ve got to fast for… Okay. As if that’s like such a big deal. Maybe another way to think about this is that feeding or eating is really interruption of fast. Throughout a 24-hour cycle, most of the time we ought to be fasted. Only a specific time we’re interrupting the fasting with eating.

But as Americans we’re prosperous, we have a lot of resources, we have a lot of food. I mean, in fact we do eat around the clock and that’s what I think is the cause for many of the health conditions that we face today, right? Probably 87% of Americans die of a preventable, a non-communicable disease and much of that have to do with food-borne illness. What I mean by that isn’t like food poisoning, but I’m talking about over-nutrition, right? Excessive nutrition. And so, it’s time for us to really look at fasting with a new lens. This is an interesting angle, something that’s part of us that’s been built into our adaptive mechanisms throughout all the ages. Now science has just begun to uncover many of the secrets of fasting and how that can help the body.

Well, it’s so true. I mean, it’s such a wonderful thing to get people to think about in the essence of breakfast, you know, break the fast and the idea that really, again, we fast for longer than we eat, obviously. What’s changed, of course, over time and in the industrial revolution and things was the fact that abundance and the western world or the countries that are wealthier actually have more chronic disease than the third world countries do. The idea of, you know, one of the biggest killers or causes of chronic medical conditions the typical hypertension, diabetes, autoimmune conditions is why? Metabolic syndrome. Metabolic syndrome…I’ve done podcasts on, folks, and the idea that really we get resistant to the insulin and then you get the problems of the modern era with chronic disease. So, abundance, wealth, and the idea of eating all over, like you said, all around the clock is not optimal for our health. The idea of fasting is something maybe we need to really make sure we circle backto  in order to help.

Now, why? Why is fasting so good for us?

That’s a very good question. So, our understanding really came from simple organisms. That’s where science always goes to when we want to understand complex mechanisms in humans. We go to a simple organism. I’m going to use a very common organism, the yeast, as a way to explain this. Okay. So, let’s say yeast exists kind of in the environment. You could kill yeast by adding hydrogen peroxide, right? These are something that that could kill because of the stress, the oxygen and stress that it causes to the yeast. You generally can kill yeast with a normal concentration of hydrogen peroxide but think about this, if the yeast fasts or do not see food for over two, three days and you add hydrogen peroxide, what happens?

It doesn’t kill the yeast anymore. It takes even a higher concentration of the hydrogen peroxide in order to kill the yeast because the yeast cell is a single cell organism, right? When it says that there’s no food coming in it goes into a different mode called the protective mode. Some people call it the stress resistant mode. Because he knows it’s not time to grow, it’s not time to reproduce. What is the time for? It’s time to protect because there’s no food coming in. It’s time to rejuvenate because that’s the time you got to recycle some of the worn out, older cellular components for new ones so it could rejuvenate itself. That is during the time where there’s no nutrients coming in, right?

It’s almost like, you know, if you think about a family’s finance, right? There’s no new income coming in. For the next day or two it might be okay, but if you go for a week then you say, “hey, there’s no income for the next week.” They say, “Oh, we’re going to do something. We’ve got to change our buying pattern. But what if income doesn’t come in for the next month? You’ll say, “Oh, we’ve got to do something. We’ve got to save. We’ve got to recycle. Let’s make do of something that that we used to throw away. Now let’s be creative.” That’s what the cells do, okay?

Similarly, looking at a higher organism, an animal like a rodent. That’s what we often use in the laboratory. When you think that depriving the rodent of nutrients, the rodent might become weaker because there’s no nutrients, but in fact surprisingly it lives longer! Thirty to sixty percent longer than if you were to feed it every day. Why is that? So, it turns out that at least on the animal level, when you turn off those nutrient sensing mechanism, meaning that when the cells do not sense food coming in, it does turn on those stress resistant pattern, right? That mode. It turns a mode that the cells go into when there’s no food around also turns out to be the pathways that supports healthy aging. That’s where the nutrition and fasting and longevity really gets connected. Now, we’ve seen this in higher level organism, in fact, the same mechanism is conserved from yeast to flies to rodents to mammals.

I think the big question for us today and where science needs to answer is what happens to humans, right? When humans fast, what happens? I think over the last 10 years there have been increasingly number of new literature research asking that question – what happens to humans when we fast? So, there are a couple of really top-line summaries if this is a good time to talk about that.

Yeah, absolutely!

One is that we know fasting alone…we have to be very careful, right? Because just think about it, fasting just to do fasting cannot be the only answer. Otherwise, look at our sort of human history, you know. Every region of the world has gone through famines, starvation, periods of starvation. If fasting alone is the good thing, then after every starvation people’s lives and health should have gone better, longevity should come. It just didn’t happen that way, right? Why? Because now we’re beginning to realize because we’re so complex, fasting has its benefits but it’s got to be done right. That’s really step one is that with a lot of popularity about fasting right now. People often forget…just like exercise, you cannot exercise 24 hours a day. That would not be good for you. It turns out it’s really the alteration between fasting and then re-feeding, the proper re-feeding, that is really the key to better health, right? Much like when you exercise, what are you doing? You’re pulling apart the muscle fiber allowing it to heal. The healing time is very important. The rest between exercise is as important as exercise. The nourishment around that is also very important. Same thing with fasting. We’re beginning to understand that it’s not the kind of blanket statement that fasting is all good for you. You have to understand your health. You have to understand what is right for you. You also have to understand is really the combination of fasting and the right feeding done in the right interval done in the right intensity that is good for you.

That’s true. I hear that a lot from patients in the essence from the analogy of they say to me, “I know what I should do, but I’m just not doing it.” It always interests me when I hear patients say that because to be honest it’s like you have an idea of what we should be doing, but there’s so much information out there to be learning about what really is the physiology. What you’re talking about now is, how do we properly fast? Then how do we properly break the fast or keep ourselves doing it right? So, what steps should listeners take to begin fasting and do it properly and particularly for longevity?

Yeah. I think step number one is to realize that fasting is different than just eating low calories. I think that there’s a lot of misconception out there thinking, Oh, yeah. I fast all the time. I just eat, you know, a couple hundred calories a day. That is not a fast. Okay? What I mean is that if the composition of what you’re eating…even though it’s only a couple hundred calories, but if your body is able to sense those nutrients then the cells are going to say, “oh, you there’s no signals of fasting because of the nutrient. I could still sense nutrients, so I’m still going to grow and just grow less.” And so, it’s like you still have money coming into the bank. It’s not as much as last year, but there’s still revenue coming in. It’s not going to change your lifestyle, okay? You just can carry more balance on your credit cards. It’s the stress of fasting, so there is a difference between low calorie diet and fasting, okay?

But it’s also important to realize that fasting doesn’t have to be done very frequently, right? That’s another amazing thing. Yes, we hear about intermittent fasting where it’s done every day. That’s just a short period of fasting. What I’m talking about is what I call the periodic fasting. These longer fasts that have been shown to improve and support health is in all the traditional fasting that people have done in religion, in culture that typically have been longer fasts. Those fasts don’t have to be done very often, why? Because it’s the stress. It’s the stress of fasting that causes your body to respond to it and then you have to allow time for the re-feeding to take place. That yin and yang can sort of complement each other, right? So, step number one is especially for those who say, “Oh, I know what to do, but I just can’t do it.” There’s good news for you! These kind of periodic fasting I’m talking about, these prolonged fasting, you don’t have to do it very often, okay? In fact, you know, when you do it too often, you’re depleting the body too much of the elements. You could do it periodically. That’s why we call it periodic fasting.

So, how frequently would you recommend and how many days, for example, are we talking about?

Yeah. It’s really difficult to put a blanket statement, but generally we know, for example, one of the key processes of fasting is called autophagy, right? I think your listeners probably have heard about that. Autophagy is a process where the cells are recycling some of the components, the old worn-out components, for new ones. That recycling process, the autophagy process, the description of that mechanism, won the Nobel Prize in 2016 by Professor Ohsumi in Japan. That process doesn’t get triggered unless you really fast for probably more than two days in humans. It probably gets started as early as 24 hours in rodents. But now we’re beginning to see that full-fledged autophagy process probably doesn’t even begin if the fast is too short, namely about a day or so. So most of the intermittent fasts I have a lot of doubts as to whether they can cause autophagy in humans because most of the data actually came from animals.

I think at least you’ve got to do two to three days as sort of the shorter fast that could trigger autophagy. That much we know, right? Anything lower than that you probably would be really good for weight loss, probably good to support your metabolism, but in terms of sort of the deep cellular impact or supporting healthy longevity lifestyle, it probably is going to require a fast that’s a little bit longer. Probably more than two days or three days.

The question, obviously, is – wow, that’s really difficult to do, right? Think about it. I mean, Dr. Murray, we remember if we go to a medical conference and they happened not to feed us we complain. Even as a physician, I was like, “What? There’s no food? This is a terrible conference!” I mean, think about how we’re used to eating a couple meals a day. The idea of just water fast for a couple of days is really challenging.

This is where Dr. Valter Longo, who’s a professor at USC, over 20 years of his career he was trying to overcome this problem, right? He realized there’s a lot of good about fasting, but people cannot do it, it’s not a pragmatic solution. So, he discovered the molecular pathways that intersect nutrition, fasting, and longevity. And so, he actually invented a product called the fasting mimicking diet. This product was actually sponsored through the NIH, through the National Institutes of Health with, you know, over 30 million dollars of federal funding to come up with a solution.

This fasting mimicking diet is meant to give you many of the benefits of a prolonged water fast without you having to fast without food for a number of days. That’s where I have the privilege of really taking the product through many of the research and development cycles to make it applied to different people in different situations.

I definitely want to hear more about this, and people do, about the fasting mimicking diet and what that exactly looks like. I guess the one thing I would say is, you know, in the cognitive decline world, in the longevity world, the intermittent fasting and the idea of a twelve to fifteen hour fast every night it’s definitely got its place.


And has shown significant improvement in people’s cognitive abilities as far as decreasing hypertension, high cholesterol, and helping with what we talked about earlier of the wealth and abundance has led us down the path of chronic disease. We don’t want people to say, “Oh good. I don’t have to intermittent fast.” Let’s make sure everybody realizes the importance.

Yes, and let me clarify a little bit. I think there are two different tools if you think about that, right?


Not everybody can run five miles per day, okay? Intermittent fasting can be done on a daily basis. Maybe you want to do it for twelve hours. Twelve is kind of what everybody should be doing, right? I mean, look beyond twelve hours you should not be eating, period. Okay, but the more you’re pushing the fasting period fourteen/ten, sixteen/eight, eighteen/six, that means you’re creating more stress to the body, right? Because if you’re fasting eighteen hours and only eat six hours…something people even do twenty-four. I mean that’s really difficult.

That’s where I think the balance between you want to give the body a lot of stress so that the cells would respond to that, but at the same time should you be doing that every day for 365 days? I think the answer is if you have metabolic goals that you want to go for then you can intensify that fasting, intermittent fasting, with longer hours. But once you reach the goals, you don’t want to be doing that every single day because it’s going to come at a cost, right? It’s like somebody says, “I need to exercise eight hours a day.” Good for you, okay. But how long can your body last if you continue to do that every day without rest? The concept of really thinking through what intermittent fasting and how many hours you want to do is one area you want to think about.

Number two is with these periodic fasting that I’m talking about, longer period of fasting, you may only need to do it once a month, maybe once every three months depending on your situation. They can bring a lot of the benefits to your body without having to make a commitment to a lifestyle every single day. They’re tools in two different buckets, and I think we should use them to our benefits.

Okay. Another question before we get into the details of the fasting mimicking diet would be as you said with exercise, you’re not going to suggest to a couch potato to go run a marathon. Someone who obviously has been a runner throughout the last ten years of their life, but they usually do 5ks or a little longer than that might be able to train and prepare within a reasonable amount of time for a marathon. Is this something where you would say to someone with the typical American three or more chronic diseases to dive right into, or is this something they should do some intermittent fasting and prepare for? What would you suggest?

Dr. Murray, you positioned it quite well here. I think it could be a matter of sequencing, too. If you never fasted before and you have some conditions, it’s probably not safe for you to fast for a prolonged period of time. Start with intermittent fasting, and in fact start with a with a shorter window. Don’t start fasting eighteen hours. Start fasting twelve hours, maybe fourteen hours. See how your body responds to it, and you already could reap some benefit.

I think the point I’m trying to make is, let’s be very clear that intermittent fasting and periodic fasting they do have different benefits even though they both can be very good for you.

Okay, so what steps should listeners take to begin fasting for longevity?

Yeah. I think the concept is shifting. For years our debate has always been – what do I eat, what do you eat, what does the government say we eat, what does the association say we eat, right? It’s always the debate. What do we eat? Now the debate is really switching a little bit more to what time do we eat, what pattern do we eat? With placing less emphasis on the substance. Now sure, you don’t want to eat junk during the times you want to eat, right? That’s common sense, but I think we’re getting a little bit more sophisticated now. It’s not just simply how much you’re eating or what you’re eating, but also the timing has a lot to do with this.

Let’s say if you’re able to restrict all your eating in an eight-hour window, ten-hour window, what you’re saying is that you will allow the body to clean itself for the fourteen hours, to rest itself, to get rid of some of these stuff, and also by the virtue of not eating during those whatever sixteen hours that you’re not eating, that means you’re also eating less during the time of the eating window. It makes a lot of sense, and so that’s certainly a good place to start.

All right. That’s awesome! So, let’s get into it then. What does the fasting mimicking diet look like? What’s the science and the clinical application of this?

Yeah. So, the fasting mimicking diet, as I mentioned, historically it was really a diet plan. It’s a five-day diet plan designed to help people take on a fasting journey because fasting on water alone is really difficult for most people, right? And so, Professor Longo has taken the knowledge of molecular medicine in human physiology and designed this structural meal plan. Essentially, it’s a five-day meal plan. Within the five days you just eat the stuff that comes in the box, and they’re really grouped by the day. Day one, day two, day three, box four, or five. You don’t need anything else outside of this box. The food inside the box is scientifically formulated to provide enough nutrients to the body, but the composition and the combination of the food actually evade the cell’s ability to detect them as nutrients. In other words, in plain language, the food tricks the body to think that there’s no food, when in fact you’re providing nutrients. It sounds really amazing, right?

It’s really based on a different definition of fasting and let me just go there for a second. A lot of people always think about fasting means no food, right? We also know that there is another level. Let’s say if you don’t give carbohydrate and you just give fat, what happens? The body actually burns the fat and produces ketones like you’re fasting. But, it’s not exactly because if you’re eating protein and eating a lot of sugar, the cells are still recognizing nutrients, oh, protein is there, amino acids are there, glucose is there, carbohydrates there. I can’t stop growing. I still have that signal of growth rather than going to that protective pathway. I’m still in the growth pathways. That is the difference, but then if you go further to look at the molecular definition of fasting, that means how do the cells know what’s fasting, well it’s when these ears and eyes are the cells, the senses of nutrients when they say there’s no food then the cells go into a fasting state. As long as you give nutrients that fall below the detection threshold of these ears and eyes of the cells for nutrients then you can actually nourish the body at the same time keeping the cells in the fasting state.

What’s the makeup of proteins, carbohydrates, fats of what’s in the box?

Yeah. There’s a lot of science around that and certainly the composition, to just speak in generic terms here, the composition is rich in plant-based fats. We know animal fats and plant-based food fats are very different. So, these are all plant-based fats taken from premium ingredients of macadamia nuts and almonds and so on and so forth. Then the carbohydrates are a complex carbohydrate with rich fiber so that the nutrient that goes into the body gets absorbed very slowly so it doesn’t activate these nutrient sensors inside the cells. Then there are very specific amino acid composition in there where it’s going to evade the cell’s ability to detect nutrients and therefore helping the cells to go into a fasted state for five days. That’s really the trick. We call that the fasting mimicking diet technology.

So, what does this look like for someone who just…okay, someone’s interested, and they want to learn more, but then they want to do this. Do you do something to prepare and then go in? And how do you get out?

Yeah, the good thing is, both are easy. Both the entry and the leaving, the exit, is quite easy. There’s no preparation needed. I mean, this whole concept, the fasting mimicking diet prepares somebody’s body. First day is a little bit higher calorie and then there are substances in there to help you to make that transition from carbohydrate-burning into fat-burning. Then from day two to day five it’s lower calories with the right composition so that your body stays in autophagy from day two to day five with the beginning of day two, day three as the cells enter into an autophagy and stay there for about three, four, five days. That fifth day all you need to do is add water. There are soups, there are bars, there are vitamins in there, there are specific glycerin drinks that support the body so that the body will not break down muscle to be to be used as a fuel. All these are very well scientifically designed to do this. Over 300,000 people have used this product worldwide, and numerous clinical studies have shown us it’s a safety and efficacy profile.

So, each day you get this box, and in the box is different information and things that you’re going to ingest. It tells you when and how long. Is there a certain time span in which you, again, ingest the things in the box?

Yeah. I mean, we understand that for most people, reducing their calories and switching away from their normal diet is already a challenge, so there is no restriction on how many hours you have to consume the diet. I think if people wanted to timeless eating on top of that, go ahead, but it’s not necessary.

Okay, and then at the end before you spoke about what’s really important is breaking the fast and getting back into your regular routine in the right way. Is there a particular way to do that?

Yeah, that’s a really important question. I think after five days, your sixth day through the tenth day is a really critical moment. You think about it. I mean, basically we have kind of squeezed all the water out of the sponge, figuratively speaking, from our body because you go through these five days of fast. Even though we’re giving you nutrients through the fasting mimicking diet, it’s still not going to be your daily nutrition, right? From day six to day seven it’s very important that we start easy because the GI system has fasted for a couple days now, right?

You really do want it to start with something simple, plant-based for the first day or so. But, from second day on, I mean, you certainly don’t want to give huge amount of animal protein. Your body’s just gone through this cleanse. You don’t want to pollute the body again, right? So, the second day if you want to start with fish, light meals. Then for the for the next couple of days get organic if you can. This is when your body is so hungry for everything. Everything you put in there including the toxins is going to be sucked up all very efficiently. Because of the fasting period, this is the time to treat your body, to nourish your body with clean nutritious food.

This is the most common question actually for a lot of prolonged user or the fasting medicine diet user after the five days of that experience is – what do I eat now? Because after five days it changes your perception of food. It changes your relationship to food. Think about for umpteen years you’re addicted to a certain kind of flavor or food. Five days without it, you’re like, wow! Your brain is retrained, it’s rewired, it’s like, well I’m no longer craving for that all, right?

And so, people’s behavior also changes. We have surveys done looking at people finishing prolonged. They feel that they have more control of their appetite. They want to begin to take charge of their health. And so, in fact, this could be a great kickstart especially now where I don’t know where we are in the pandemic, seriously. Coming out of it and then I say, “Well, maybe not so quick.”


But, I think this can be a good time for us to kickstart our health with a fasting mimicking diet approach.

Yeah! I mean, folks in the foundational functional medicine concept definitely use what’s called that comprehensive elimination diet to try and help people detox and then identify what food triggers or sensitivities they might have through a systematic re-challenging after an elimination diet for let’s say twenty-one days. I’ve used that for years with people and as we do it…we do it for so many reasons, but one of the other reasons is, as you said, to shift the brain and shift the lifestyle. It’s sort of a, whoa! Now I can’t go back to where I was.


I need to shift. So, it sounds like this might be even for folks that have done the elimination diet. I always recommend to folks at least a couple times a year, that are that are healthy and ready to do this, go into some form of a detox and a cleanse. It sounds like a couple times a year this could be the avenue in which people use. Now, one other question though is what about water during these five days. Is it unlimited? Does any of that have a rule to it?

In fact, we encourage fluid intake because you’re not eating a lot. You’ve got to drink a lot of fluid. In fact, you know, some of the headaches people experience, part of it is caffeine withdrawal. Part of it’s just dehydration, right? During fasting period it’s important to keep hydrated. There’s no problem.

Yeah, that goes without saying. Absolutely. So, wow! Dr. Hsu, this is really, really interesting. If people are wanting to learn more, where can listeners find more information and find out more about this fasting mimicking diet?

Yeah, I know that you have a curious listening crowd and so I’ll share three resources. One is if you are interested in the product, you want to learn more about the product, you could go to ProLon, That’s where you’re going to get a lot of the description of the product. For general knowledge about fasting, there’s a great website called It’s a site where there’s just a whole lot of knowledge about fasting. A lot of people are sharing sort of expertise on that platform, a lot of focused articles on different ways of fasting, so that’s a good website to go for general fasting knowledge. For the company that makes ProLon, the FMD, you want to understand our technology, our science, our commitment, you can go to

Awesome! So that idea of the product is the ProLon FMD (fasting mimicking diet) at


Excellent! All right, well thank you so much for this, Dr. Hsu. It’s very intriguing, this idea of the fasting mimicking diet. I’m going to have to…I haven’t done it before, yet. I have heard of it and been interested to learn more, so this has been a great conversation. Thank you so much.

Thank you, Dr. Murray.

So, the last question I always like to ask everyone – I have a feeling I might know what line you’re going to take – is what number one secret for living a healthy life would you share with the audience?

Wow, that’s a that’s a challenging question because I have many lines!


I would say that I think knowledge is essential, but it is not sufficient to change our health. Most of us know what to do, we just can’t do it. And so, my personal take is you’ve got to keep that joy of the heart. I think that mental health, that motivation is key. It’s not the knowledge, it’s not even the determination, right? It’s where your heart is, you know? Keep that motivation, keep that fervent for life, that enthusiasm for life, that joyful heart. I think that drives all the health behavior. Maybe I’ll leave that with your audience.

That’s awesome! Thank you so much! I thought you might go down the fasting path!

Fasting comes immediately second! You have to have the motivation to do it.

I couldn’t agree with you more, that if your heart and you don’t have joy in your life then then what do you have? So, thank you so much for that. That’s awesome!

Thank you, Dr. Murray.

Doctor, thank you for joining us and thank you for teaching us about fasting and your health. Take care, everyone!


Connect with Dr. Hsu


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