David Taylor, MD (Host): Hello and welcome back to the On Call podcast at Riverwood Healthcare Center in Aiken. Our guest today is, again, Dr. Timothy Arnold, here to continue a discussion about nutrition and he's going to promote a bunch of fad diets that are going to get you thin instantly and you're going to be perfectly healthy and live to 110, right, Tim?

Dr. Timothy Arnold: Yeah. Exactly.

Host: So hopefully, you've had a chance to listen to our previous podcasts where we've focused on healthspan, and healthspan is both living longer lives, but healthier and more functional lives, and that is really incorporates wellness as a whole, which involves exercise, sleep, and nutrition. And the last podcast and this podcast are trying to focus on nutrition. Nutrition is such a wide-ranging topic. We have multiple digressions and diversions, and we'll have those here as we incorporate them into how they interact with exercise and all that. But we'll try to, in this podcast, get into some specific discussion about specific diets as well, because people oftentimes have questions about those. And Tim, this is something you deal with firsthand is, "Hey, I'm going to go on the keto diet," or "What diet do you recommend?" And maybe you could recap what you had from the last one about that you don't recommend a specific diet.

Tim Arnold, MD: Yeah, I'm actually going to take this one all the way back to the very beginning first of all. So if a patient comes in and asks me about a specific diet, the first thing I ask them is, are you exercising?

Host: Yeah, this is a good recap.

Tim Arnold, MD: And then, the question is, "Is how are you sleeping?" That sleep has such a dramatic impact on the foods that we eat and how our body processes those foods, whether they're healthy foods or not. I wear a continuous glucose monitor on occasion. I've got one on my arm right at the moment. And if I don't sleep well, I can see the foods that I eat respond dramatically differently in my body. So, those first two things are really important, exercise and sleep. So before I'll have a conversation about a diet, those two things really sort of need to happen.

If we want to talk about a diet specifically, my first answer to them is I don't ascribe to any specific diet. You can put whatever name in front of a diet you want to put in front of it. Paleo, Keto, the potato diet, whatever, it really doesn't matter to me. What I'm really going to focus on is to get the ultraprocessed foods out of your diet, get all the refined foods, all the stuff that has more than five ingredients, as I had stated on the previous podcast.

For those who didn't hear it, I'll just do a quick recap here. So, if you look at the food label and there is more than five ingredients on that food label, you're probably getting into a processed food. And if one of those five foods, or one of those five ingredients, are not something that you would see in your seasoning cabinet, it's probably a processed food. Now, it's a little bit hard. Like, I think Mountain Dew probably has three or four ingredients in it. It probably meets that five-ingredient rule. I don't know, but...

Host: It has water, it has high fructose corn syrup, it has orange juice. I used to argue that it was a health food because it had orange juice, but that's the third ingredient. And corn, you know, that's good for farmers in Iowa. So, how could you not support Mountain Dew? Yeah. This was my foolish 20-year-old thinking.

Tim Arnold, MD: Yeah. So, some things don't apply to that rule, but I think most of the listeners here will kind of get the sentiment that if it's not a whole food, if it didn't come straight from the ground or straight from the animal, that it's probably a processed food. And that is really the issue that we have in our society, in our country with our metabolic health and our obesity epidemic and that kind of thing.

Host: Yeah. So for anybody who's just picking this up now, please do listen to the first episode of this, which is our third podcast. It goes into these concepts in more detail, but not so much detail that you're going to get lost in all the weeds. It's really good overview on some of the basics of nutrition.

Tim Arnold, MD: So, this does get a little bit confusing because the word keto in the popular press is different than what a true ketogenic diet is.

Host: Yeah.

Tim Arnold, MD: So, a true ketogenic diet means that the body is running essentially on fat. Not running on really much of any carbohydrates. And in the process of doing so, when we're running on fats, as a product of that metabolism, we make these things called ketones. And a true ketogenic diet, you should be able to test for those ketones in urine. And there's some other ways to do poke your finger and check your blood and you can measure the amount of ketones, something called beta-hydroxybutyrate in your blood. And you can actually measure a level and you can say whether or not you're truly in this keto diet or not. That's a more scientific approach.

I think what most patients are talking about when they're talking about a keto diet is really a high-protein diet, high-fat diet, low-carbohydrate diet. When it first kind of came around back in the day with Atkins and the keto diet, we had lots of patients that were eating lots and lots and lots of fat. And granted they would definitely go into ketosis because that's the energy fuel that was coming into their system. They oftentimes are eating really not very healthy fats. And that was kind of the first kind of round of keto, maybe 15 or 20 years ago, that I saw in my patients was really lots of unhealthy fats. So, lots of deep fried hamburger and sausages and lots of heavy oils and cheeses and really unhealthy fats. And they went into ketosis and they lost some weight. Their bodies had to make that adjustment and they did. But what I saw then was it wasn't really sustainable. And then, I kind of saw over the next 10 years, like the last five to 10 years, when a patient comes in and says they're doing keto, what they're really talking about is basically just a high protein diet, trying to get their carbohydrates down as much as they can, and maybe not as much of those unhealthy fats is kind of what I'm seeing.

Host: Yeah.

Tim Arnold, MD: So, patients may ask me, "Well, how do I do that?" And so then, we start to talk about, "Well, tell me what you know about proteins and let's talk about the proteins that you eat and what are the typical proteins in your diet and how do you plan on getting into this sort of keto kind of high-protein diet." And then, I'll let the conversation take it where it's going to go from there.

Host: Do you have people that bring this up to you often? Is this a common thing that you will hear in wellness visits or in your clinic visits or out in the community? Or is this not as common, especially since it's evolved over time? It's not "one of the more fad diets of the moment" like Atkins was way back 20 years ago.

Tim Arnold, MD: I would say I hear about a less so now than I did previously. But still, I would bet almost on a weekly basis, I have a patient telling me that they're trying to be more sort of keto-friendly.

Host: Yeah.

Tim Arnold, MD: One of the things that I really caution my patients on with the keto diet is you can go out and buy all kinds of keto bars and all kinds of keto products in the grocery store. And if you look at that bar, that product, it doesn't adhere to my rule number one, and that is five or less ingredients and ingredients that you can have on your shelf on your seasoning cabinet. Most of those keto bars are highly processed types of essentially high protein, high fats, but lots and lots of processed stuff meant to sit on the shelf for months, if not years at a time. And I think that is, again, one of the problems that we're seeing is this really high processed, ultra refined diet. And so, I really encourage my patients, if you're really wanting to go keto, it really needs to be some source of high quality protein, whether that be plant or animal, unprocessed as much as possible, needs to be in its most original form that it came from this earth or however it was produced. And then, a little bit of vegetables. And really, that's going to be a nice keto diet right there. So, some whole vegetables and then some really healthy sort of originally sourced protein, whether you're going to eat meat or you're going to find some sort of high quality plant protein to get your protein up in your diet.

And then, if you want to add those fats and oils to truly be on the keto side, make sure that we're eating really healthy oils. The monounsaturated fatty acids like avocado or olive oil are the two that I would really steer most patients towards. We can kind of get in the weeds a little bit about coconut oil and some things like that, but I want to stay away from the refined oils like the canola oils and some of those seed oils. If you really want to get keto and you really want to get into that high fat, sort of just make sure it's a really healthy fat.

Host: This is a little digression, if people ask you what's wrong with seed oils, what is the concern with seed oils?

Tim Arnold, MD: An oil is a long-chain carbohydrate. So, oh gosh, this is going to get technical. How am I going to explain this here, Dave? So, everyone's probably heard of saturated or monounsaturated or trans fats, those kinds of things. It has to do with the bonds between the carbon atoms and the hydrogen atoms in the molecule of the fat. And to try to keep the super high level, some of those seed oils will have some of the structure, the three-dimensional structure in these bonds between these atoms that are unfavorable to our health and our chemistries in our bodies and physiology in our body. Let's just kind of leave it at that. The monounsaturated fatty acids like avocado oil and some of the things you see in olive oil, a much more favorable response in our body. The physiology is better. The outcomes are better. We'll leave it at that.

Host: Yeah, I think that's a reasonable way to leave it, and the chemistry is hard to understand to begin with. If somebody asked you, "Okay, great, but I use canola oil or vegetable oil, and vegetable oil maybe isn't the good one to choose, but I use a seed oil like canola oil because it can handle high heat, and I can fry my fish that I caught in it. The olive oil just burns when I do it. I can't get crispy fish with it." Do you have a recommendation?

Tim Arnold, MD: Yeah. So, that depends on the quality of the olive oil. So, I have an olive oil that I use on a daily basis that I don't remember what the smoke point is, but it's really high. It's higher than a vast majority of the seed oils are. And that has to do with the quality of that olive oil. Avocado oils are the same. If you get a nice expeller-pressed, which means that it was pushed out of the avocado via a physical method, not a chemical method, those oftentimes have a very high smoke point and the avocado oil again has a very fine, nice light flavor. So if you're wanting to fry fish or something like that, an avocado oil is a great choice.

And then, if you get a really, really high quality olive oil, the smoke point can be as high or higher than the typical seed oil is. And I use one on a daily basis, and everyone that comes to my house gets a free bottle actually. I hand it out, and it's expensive stuff, but I think it's so important that I give gifts away of bottles of olive oil all the time now.

Host: Yeah. Okay. That's a great useful tip. So, some quick Google searching is going to be able to find you high smoke point oils that are healthy oils that you can use in place of those traditional high heat oils that you're going to easily find. It might cost a little more money than you would expect to spend for some oil, but that's probably an investment in your health that you would advise making.

Tim Arnold, MD: Absolutely.

Host: Good. Great tip. So, again, not to lose ourselves in the weeds of any individual diet, just touching the overview of each of these diets, what would you say the diet you get asked about most is? Is it keto or something else?

Tim Arnold, MD: Most recently, it's probably been intermittent fasting actually.

Host: Well, all right. I definitely want to touch on intermittent fasting and that can be a hard topic. And speaking of going back to our last podcast and talking about studies, you may recall three months ago, one of the newspapers reporting that intermittent fasting leads to more cardiovascular, I believe, deaths. Do you remember seeing this study come out?

Tim Arnold, MD: I do. And I remember reading a really good critique on it, and I don't remember all the specifics of it. But at the end of the day, it gets back to what we talked about with our previous podcast, and we have to be really careful what we read, and we have to really be careful about what conclusions a newspaper journalist draws from a scientific article or even maybe the scientists who published that article. I don't remember the reasons why that article-- once I got a chance to look at it, really, in my mind, I felt like the data here isn't good. The conclusions are not good. I'd have to go back and look at it again to remember the details.

Host: I actually agree. I don't remember the specifics. I remember reading it and then remember looking at two people who I rely on that review data as part of my weekly research into things, and they pretty much ripped that study to shreds in terms of its quality. But immediately, there's this narrative now that starts to be developed that, "Oh, this intermittent fasting is actually a bad thing" when you can't draw that conclusion from the study that came out.

Dr. Timothy Arnold: Right. I think it was the randomization of the groups, and I think it was also some confounding variables that they didn't pull out in the two different populations they were comparing, if I remember correctly. That's my kind of high level memory of it.

Host: Well, let's go into what is intermittent fasting? Since this is a great one, for anybody who's on the bro podcasting, or bro podcastistan, that every young man has heard of intermittent fasting at this point, and probably most younger women and even some of our older population knows about intermittent fasting at this point, but yet there's still a lot of confusion about it.

Tim Arnold, MD: Well, yeah, so this is another one where I think the technical definition of intermittent fasting is different than what is being discussed out in the general public. So, I think maybe a better word is time-restricted eating or time-restricted feeding. And basically, what it implies is that you only get your calories during a certain portion of the day. So, that could be an eight-hour window you get all of your calories, and the other, the remaining part of the day, there are no calories coming in. It could be six-hour, it could be four-hour, two-hour whatever it might be. But that's really that kind of that time-restricted feeding. I think a lot of people are using that same thing for the word intermittent fasting.

Now, I want to break this down just a little bit, because this is one of the things that kind of bugs me a little bit about intermittent fasting. If you look at the definition of intermittent fasting, there's the word intermittent in there. That doesn't mean that you do it every single day. Fasting typically means again, you're not eating during a particular period of time. So intermittent fasting, if you really break it down, it should be intermittent. You're not doing it every single day. And there's a group, there's a chunk of time that you're not getting any calories in. That's different than what I think a lot of people are doing with time-restricted feeding. Well, I only eat two meals a day, or I get all of my calories in between 2:00 and 6:00 throughout the day, but I do it every single day. Well, that's not intermittent. That's just time-restricted feeding. You're just restricting your calories to this specific window, and you're doing it every single day. That's not intermittent fasting. Those are kind of two different things and they physiologically work a little bit differently in the body in terms of how the body responds to intermittently not eating anything for an extended period of time.

Host: Can you define extended period of time?

Tim Arnold, MD: Yeah. So, this is where it gets a little bit more technical. So, the way that you would measure that is what is the body doing in the presence of no calories coming in? How is it starting to change its physiology? How is it responding? And for sure, a 12-hour window, we start to see a little bit of changes. So, that's just an overnight. "Ate at 6:00 p.m. I didn't eat anything and I slept and I got up at 6:00 a.m. in the morning," there's a 12-hour window in there. We do start to see some changes in terms of the physiology of the body. We won't get into the weeds on that one. But however, more importantly, we really start to see those things start to happen at 24 hours.

So, the physiology of the body really starts to change how our body is responding to that scenario where we don't have any calories coming in. And again, last podcast, we talked about carbohydrates, fats, and proteins. So, all of those three systems start to change how they work. Remember that our body is going to try to keep our blood sugar at, you know, 90 or above or 60, 70, 80 and above all the time, because that's primarily what our brain runs on, is sugar, although it can actually run on ketones and lactate, but we're getting in the weeds again. But intermittent fasting, in my mind, a longer period of time is going to be at a minimum 12 hours, but really we should be talking really more about 24 hours and beyond, if we're really talking about intermittent. So, occasionally, not every single day, fasting where we want our body to behave and do something different. It's probably going to be pushing up into that 24-hour timeframe or longer versus time-restricted feeding, which is what most of my patients come in and tell me they're intermittent fasting. What they're really doing is time-restricted feeding. They're just eating between 2:00 and 6:00 p.m. And they're doing that every single day. The body responds completely differently in that scenario.

Host: Do you want to highlight some of those differences?

Tim Arnold, MD: Yeah. So if I can use the example of one meal a day, so I do have some patients that are just doing one meal a day and they're doing intermittent fasting, I'm just eating one meal a day. So, they don't have any breakfast, they don't have any lunch. They just have dinner in the evening. Now, a couple of things start to happen. Their total amount of calories that they're getting is going down. So, this is a way to reduce the total amount of calories coming in in a day. It's pretty hard, although it's not impossible if you're eating a poorly formed diet to get 2,000 calories or above in one meal. If you're eating a really healthy diet, you're getting lots of fiber, lots of vegetables, raw vegetables, and some protein and some fruits, it's pretty hard to get over the total amount of calories that you're going to need in a day. So, probably, you're going to be a little bit lower than what you need for total to maintain body weight. So, you're probably going to start to lose weight if you're eating that one meal a day, because you're under your total calorie need. You just can't get it all in in one meal.

So over time, the body starts to say, "Gosh, I'm kind of in this starvation mode here. Every single day, I only get one meal and I'm under my total calorie that I need to maintain my body weight. I better start to slow things down a little bit because this seems like this is going on for a long period of time. I'm in a famine right now, and I better hold on to everything I've got so that I can survive this famine." And I'm adding emotional words to something that's really complicated physiologic response, but just helps for good understanding. So if we're eating this one meal a day over a long period of time, or we have this kind of smaller time-restricted feeding window, every single day, weeks after weeks, months after months, the body basically says, "You know what? I'm going to turn the whole system down. I'm going to turn the basal metabolic rate down. I'm going to turn on my activity down. I'm going to slow down in terms of my movements and my energy, my workouts, whatever else it might be." And so ultimately, we end up with a organism, a body that's going slower. That's not what we want. We want our bodies to be strong and energetic and to have lots of energy and to move and to be able to do the things that we need to do in a day. We don't want things slowed down and turned down. So, this one meal a day or potentially eating in a smaller time-restricted feeding window every single day, day after day after day, month after month, ultimately, in the end, it looks like it probably isn't overly helpful other than you may lose some weight over time, but are we in a better position?

Host: Yeah. Do you have a timeframe, a general just framework when those changes where your body starts shutting things down, your basal metabolic rate goes down, your set points are going to change? Is there a point in time that you could tell people? I understand that'll be individualized to a degree.

Tim Arnold, MD: I don't think I know that data. I don't know what that timeframe is.

Host: I don't either.

Tim Arnold, MD: I probably knew it at one point, but I don't know it right now.

Host: Okay.

Tim Arnold, MD: What I do think is a better idea-- let's step back a second. So, one of the first things I ask patients about intermittent fasting is what are your goals? What are you trying to do? Why are we doing this? Is it because you want to lose weight? Is it because you want to help reduce your blood pressure? Is it because you want to help reduce your pre-diabetes, your diabetes? What is it that we're trying to work towards?

Host: And what do they usually tell you?

Tim Arnold, MD: Generally, they want to lose weight. And time-restricted feeding or intermittent fasting is a way to reduce the total amount of calories that we get in. Now, this gets into the whole "Is one calorie the same as another calorie?" debate. And is this really just that I'm eating too much or I'm getting too many calories in? And the answer to that, and maybe you can expound more on that question, Dave, maybe I didn't explain it very well, but there's lots of, I think, emotion around this, there's lots of politics around this. There's lots of discussion about shaming and that kind of thing that just because someone might be overweight, that it's just because they're overeating. And if they just ate less, they would be fine. And they just need to be stronger, have stronger will. That is absolutely not the case. But both statements apply. There is a law of thermodynamics here. The amount of calories in does play an impact on how much weight we carry.

But the other part to this is that the types of calories that we take in hijacks our emotional response, it hijacks our brain, it hijacks satiety and our hunger and all of those things. So, this is not about, if someone comes in and says, "I want to lose weight, I want to intermittent fast," we do have to talk about two things. We have to talk one about the total amount of calories that you're getting in and intermittent fasting is a way or time-restricted feeding is a way to reduce the total amount of calories that you're getting in. And that's going to need to happen for you to lose weight. Law of thermodynamics still applies. The energy has to go down.

Host: Yeah. I think that's important for people to understand, just we can reiterate it. And we didn't really say it in the last podcast. Your calories out has to be more than your calories in over a period of time. And what that period of time is to lose weight. And is it still 3,500 calories per pound to lose a pound? So, that's the deficit you need to lose a pound. And do you still say, try not to lose more than two pounds a week?

Tim Arnold, MD: Yep. One to two pounds a week is pretty healthy. More than that, you're going to start to lose some muscle.

Host: I will expound a little bit that you do see narratives, what you listen to, body shaming, anybody's body is just fine. There isn't one right answer here. There are health consequences to obesity. And metabolic syndrome is a real problem, and obesity is part of that insulin resistance is part of that, dyslipidemia is part of that. All can be tied to nutrition, exercise, the things that we're talking about.

All that said, there also are social pressures on both men and women, especially maybe women from a visual aspect on what the ideal body is, how you're supposed to look, and it's not okay, and the shaming that happens as part of that, and it's a very complex process, and the amount of calories in versus amount of calories out is not like you have been describing with the time-restricted eating and the changes that happen. Your body can change that. Your body has the ability to regulate what your basal metabolic rate is. Well, you know, it can't change it in an unlimited fashion. There is the ability to eat less calories and still not lose weight because your metabolism has actually changed.

Tim Arnold, MD: Right. And so, the statement of a calorie is a calorie is a calorie from a thermodynamics perspective, from a physics perspective, yes, that is accurate. But from a human being or a physiologic body, that is absolutely not the case. So, one calorie of one kind of food does not equal one calorie of another kind of food because of how our brain and our bodies respond to that calorie that's coming in. So if you're trying to do intermittent fasting to lose weight, and it is not about simply just saying eat less food and you're going to lose weight, it's not about just if you had more willpower or you were a stronger person, that is absolutely not the case. It doesn't mean you're a bad person. It doesn't mean you don't have willpower. It doesn't mean you don't have strength. What's happening here has to do with the environment that we're in. And the environment that we're in is this highly processed, highly refined, highly palatable food source that hijacks our brains and our bodies to push us to eat more. And ultimately, the amount of calories that we get in this highly processed way really affects how our bodies respond.

For example, I'll use the example of high fructose corn syrup. Now, fructose is a sugar. It's in fruit, as the name implies, fructose. It is a type of carbohydrate. It is a type of rapidly burning fuel like any other sugar or refined carbohydrate. When it hits the liver, after you've eaten it, inside each individual liver cell, that liver cell sees a state of starvation as a part of processing that fructose. And I'm really taking a ton of data and I'm simplifying it down into a couple of easy statements, but the long and the short of it is that that individual liver cell is in a state of starvation for a period of time as it's processing this fruit energy, this fruit sugar. And because of that, the signals go out to the body to say, "I'm in trouble. I need to eat more food. I better eat more." And it really hijacks the system. And that's just a great example of this highly refined, highly processed food and how our body is not meant to do that.

So when I say a calorie is not equal a calorie is not equal a calorie, from a physics perspective, it does. But from a physiologic perspective, it does not. And so, the types of foods that we eat make a difference, but also the total quantity of foods that we eat make a difference. So, this is not about willpower, this is not about strength. It's about getting our relationship with food correct, eating the correct kinds of food. And if you need to then, you can calorie restrict via time-restricted feeding or intermittent fasting or whatever it might be to try to get those total calories down.

Host: I think that's a good summary. One simple way that I've remembered telling patients or other people who've asked me about it, with the high fructose corn syrup, in addition to what you described, fructose is one of the simple sugars. Sucrose, table sugar is, I believe, fructose and glucose, if I remember right. And so, right there, there's one step where that has to be broken down. That is a step that fructose does not require.

Tim Arnold, MD: Correct.

Host: Just as a very simple way of saying not that sucrose is something you want a ton of either, but just an example of how ultraprocessed something like high fructose corn syrup can be. So, going back to intermittent fasting and time-restricted eating, and I think for you and I, we should probably refer more to time-restricted eating so people understand that's what we mean versus intermittent fasting. Do you caution people about if you're eating less calories? But in our previous podcast, we talked about the importance of a certain amount of protein per day, it can be challenging to get that amount of protein in and the balance going into time-restricted eating requires.

Tim Arnold, MD: Yeah. It's definitely a challenge. So if patients are going to time-restrict feed or eat, if they've got a six or eight-hour window, I really encourage them, they need to get as much protein in or get their goal protein in during that timeframe, which is a challenge and they need to come up with a plan for how are they going to do that? Whether it's a protein powder supplement, a high-quality whey protein powder supplement or pea protein or brown rice or whatever it might be, but they need to sort of make a plan for that, because what we don't want to have happen during this weight loss that they're trying to shoot for is to lose a bunch of lean muscle mass.

As I had stated in the last podcast, our muscle is our biggest endocrine organ in our body. It produces all these hormones and signals to the rest of our body and tells us kind of our health status should be. And it's the biggest longevity organ we have. Liver would be number two. And we don't want to lose that longevity organ, that is our skeletal muscle mass. So, getting that protein up during that timeframe is really important.

Now, if someone is going to do a true intermittent fast, where they're going to not eat anything, nothing but water, maybe a little bit of salt for 24 hours or beyond, they will likely lose a little bit of muscle mass because we need some turnover of that protein that will likely happen. So, that is one of the negative consequences of a true intermittent fast where you pick one day or maybe two days and you have nothing. I don't recommend that for patients, just carte blanche. It's individual per patient. There are some that that would be a very dangerous thing to do. So, I really want to be clear, do not do a 24 or a 36 or 48-hour fast without talking with your healthcare provider first. It could be a very dangerous thing to do. But those where it does make some sense, we do start to talk about, "Okay, well, on the days that you're not intermittent fasting, what are we doing to maintain that muscle mass? What are we doing to maintain that protein intake so that we keep that muscle mass up if you are going to do a true intermittent fast where you're off of any intake at all other than water for more than 24 hours?"

Host: Yeah, let's go into that. If somebody needs to say, I really am interested in fasting and not time-restricted eating, but actually doing some intermittent fasts, where would you have them start? Would you try for 24 hours? What's the framework you would pick?

Tim Arnold, MD: If they have always been a three-meal a day person, then we have to start out real slow. And we start off with basically just using your 12-hour night time as your first kind of block and then add into there no breakfast. So, you're just going from your evening meal to lunch the next day. And I have patients do that two to three days a week for a month or so. And then, they can start to push in a little bit more, maybe a 24 hours. So, they're going from evening meal to evening meal. So, they're missing both breakfast and lunch. They need to keep their hydration up. You'll need lots of hydration, sometimes a little bit of salt during that timeframe, and two to three days a week only. And again, I just want to reemphasize this is not something that the listener that's listening to this podcast right now should just go out and do. You really need to speak with your healthcare provider first before you do it. It can be fairly dangerous depending on the situation, and your overall health status.

Host: That's a great disclaimer. Don't just start doing it.

Tim Arnold, MD: Right. But this is not something that you can't jump into a 24 or 36, even if you're a healthy individual right off the bat. It's not going to go well. You're going to feel terrible. It's not going to be fun. So, take it slow.

Host: Good advice. Good advice. So if somebody came to you and said, "Hey, I have a friend who is doing these 24 or 48 hour fasts at times. Why are they doing that?" What's the benefit of that?

Tim Arnold, MD: Well, I would ask their friend, because most people it's because they want to lose weight, that's generally the reason. But then, there are some that want to do the intermittent fast for some longevity benefits and there are potentially, maybe. I think the data is still out a little bit, I'm not sure that we know fully, but there's some processes called a mitophagy or autophagy, where the body basically breaks down old cells that are not functioning very well, or old mitochondria. Mitophagy, for those listeners, I remember back to their high school science, mitochondria are these little things inside of our cells that generate the energy in our cells. So, it is the powerhouse of the cell. You maybe remember that from your high school biology. It is the place inside the cell that makes the energy. And the mitochondria is very highly thought to be involved in the process of longevity and aging. And it looks like we can kind of get rid of these old mitochondria that are not working very well and make new ones sometimes through fasting. However, again, the data is not super strong on that yet, but that's what a lot of the reasons are that people are doing intermittent fasting.

Host: A quick diversion. Exercise can help you upregulate mitochondria. So going back to exercise, just for everybody, we're going to keep hammering on exercise.

Tim Arnold, MD: Absolutely. And the effect there is probably magnitudes higher.

Host: Why don't you real briefly, and this is gonna be challenging, why don't you real briefly touch on mTOR suppression?

Tim Arnold, MD: Yeah. So, mTOR stands for mammalian target of rapamycin. It is a process in our cell that tells our cell to grow and divide or to stop growing and stop dividing. It's the most generic way I can state it. So if you're trying to build a healthy muscle cell or you're trying build any other healthy cell in our body, we have to turn on mTOR to do that to make that cell divide and to grow. This is a process that is highly conserved among all sort of animal species. And so, what I mean by that is this process occurs in worms and flies and reptiles and dogs and cats and humans and horses and fish and all those kinds of things.

And so, from a scientific perspective, we look at this and think, gosh, if the same exact process is found in all these different species, going from the lowest organisms, yeast and whatever else, all the way up to human beings, this must be really important. And so, mTOR is thought to be involved in this kind of regulation of growth and divide-- essentially not grow and divide-- a lot of it's felt to be involved in a lot of these longevity processes. And we know that as we exercise, we turn on mTOR as we eat protein in this thing called leucine, it's amino acid in protein, turns on mTOR. We want mTOR turned on to build healthy cells, but we also want it turned off so that we don't build cancer cells. So, mTOR is really important in longevity from those perspectives. Did I give enough of an overview there or do you want to add to that, Dave?

Host: No, I think that's really good. And so, fasting is a way that you can suppress it. How long do you need to be fasting to get mTOR suppression?

Tim Arnold, MD: Well, to really get into good mTOR suppression, it looks like it's 24 or beyond.

Host: Yeah. Is there a frequency in a year? Like how many 24-hour fasts? Do you have even an idea of a framework what that might look like?

Tim Arnold, MD: I don't think anybody knows.

Host: Okay. This is kind of frontier of nutritional medicine on one aspect.

Tim Arnold, MD: Yep.

Host: There'll be, we could say, more to come as we learn more. All right. Well, that's a good overview on intermittent fasting and time-restricted eating. We'll probably get some questions about that, some individual questions that we can help clarify in the future. We're kind of nearing some of our time limits here. Let's quickly talk about paleo and carnivore, and we don't have to get into the details of those or any others that people may want to bring up at some point. But what I would like you to do is help us with any cautionary advice that you might give somebody who's going to be looking at the carnivore diet or paleo, even though those can be ill-defined. Can you just give some general advice that you would say, "Hey, you need to be cautious of this," you know, if somebody's going to embark on those diets?

Tim Arnold, MD: So, the first thing I think about is fiber. With a lot of those diets, they're really fairly devoid in fiber, particularly carnivore for sure is pretty devoid in fiber. And our gut microbiome is really, really important for our general overall health. And we're missing a lot of the fiber that that gut microbiome needs, particularly in a carnivore diet. Keto, the one that I'm a little bit concerned about with keto is we see some fairly significant abnormalities in lipid profiles, so cholesterol profiles. People have heard of LDL, the "bad", that's really not a good term, we shouldn't be using the word bad cholesterol, but a type of fat in our blood called LDL and what it does to that and how that relates to our cardiovascular risk. So, I'm always a little bit concerned about that with the keto diet as well. So, those are two things that kind of come to my mind.

And then again, I always sort of want to go back to what are you going to be successful with long term because a diet by definition is something that's typically temporary. So whenever we talk about a diet, whether it's keto or paleo or whatever it might be, is this going to be workable for you for the rest of your life? If there's something that you're going to do temporary and you're going to use it as a jumpstart, that's great. I would love you to lose weight or to get healthier as a jumpstart. But how are you going to apply that to the years that come? And what we really want to avoid is this yo-yo, up and down and up and down and up and down. And that could be healthy, not healthy, healthy, not healthy. Or it could be weight, lose weight, weight, lose weight. And diet by definition is temporary. So, let's find something that you can be successful with that you can do forever. And whether or not there are components of each one of these diets that you want to mix in so that you can be successful, great, but let's find something that we know that you can do in your life. Everybody's got different life circumstances.

Host: Right. You know, you and I've been in Medicine now a long time. We're getting long in the tooth, or the teeth. I'm in Kentucky or Iowa, it's the tooth. And in Minnesota, it's the teeth. But we've seen probably more people yo-yo than vice versa, sadly. And that speaks to exactly what you're talking about. When you do one of these diets, whatever this diet may be, even if you consider intermittent fasting or time-restricted eating a diet. If you don't stick with it, you're likely going to end up back in the position you were without something that's sustainable, and keeping that forefront in mind as you do some of these changes is very important.

Tim Arnold, MD: Yep.

Host: All right. We have a question, Would you want to field that question?

Tim Arnold, MD: Yeah. So, the question we have here, what are the options for people who don't cook? Also, are there any restaurants or stores that are good to shop at? And so, I'm going to go back to what I said in the very, very, very beginning. And that is if you are looking at what's on the menu and it's got really complex amounts of processed foods in it, if you know that it's a processed food, this is probably not something that you should be eating. So if we can stick to those restaurants that cater towards more whole foods, and I don't really want to mention a specific restaurant, I'm not sure that we can do that on air, but endorse one or another, but I think we are all aware of those restaurants that really focus on just the whole food. It's just a whole piece of meat. It's a whole vegetable, maybe seasoned nicely. That's what we're looking for. Think of protein, vegetables, nuts, seeds, berries. If you can find foods that are going to fit in those groups at any restaurant, it's a great restaurant to shop at or to eat at or store.

Yeah, if we're shopping at the store, that old statement, everyone's heard, shop the outside of the store is a great way to kind of think about it a little bit. When you shop the outside of the store, what do you get? You get the fruits, you get the vegetables, you get the meats, you maybe get some dairies, maybe get some frozen stuff. Generally, that's going to be again, vegetables, that kind of thing. And you're done. All the stuff in the center --

Host: How about that Cinnamon Toast Crunch, though?

Tim Arnold, MD: Yeah, no. No. No, when people ask me about eating stuff out of a can, all the stuff in the center of the store, what I generally say, and I eat stuff out of a can, we should probably talk about that as well. What do we eat? But when you eat something out of a can, particularly a canned vegetable, unless you canned it yourself, I tell people, throw away the vegetable, eat the can, it's better for you. Chomp on the can, that's better for you.

So, we should probably be real here and talk to people about what we eat. Are we perfect? Absolutely not. Do I love my chocolate pretzel chips, which is a refined food ultraprocessed food? Absolutely, I do. I am not perfect. No one's perfect. This is not what we're looking for here. Do I love my sweets? Absolutely. Do I struggle with it? Absolutely. There are days that I eat foods that I know I shouldn't be eating, 100%. There are days when I think, what in the world, Tim? But what I really try to do is try to not beat myself up about it and try to say, "Well, today's the day. I'm going to learn from today. I'm going to move on tomorrow. And tomorrow when I get that craving to eat that food, whatever it might be, my plan is to do this. My plan is to go for a walk. My plan is to just remind myself, "Tim, be in the moment. I know that you're hungry. I know that you want something good. Let's make a good choice." And sometimes I'm successful and sometimes I'm not. Sometimes I get it right and sometimes I totally fall off the wagon and I eat those big huge chocolate chip cookies at the hospital there that are on the counter sitting there. You know, those things are fantastic. Should I eat those? Probably not, but I do every once in a while.

So, I think it's important for patients to know that this is not about perfection. We're just really talking about here are the choices that we can make the best as we can. We're going to make mistakes, we're going to fall over, we're going to get back up again, and we're going to try again the next day.

Host: Yeah, I'll reiterate that. As we've gone through this particular series of podcasts thus far, I tend to be really good with exercise, though I struggle with aspects of exercise. I'm more inclined to do cardio, less inclined to make sure I'm getting good strength work again. And there's a constant battle of making sure you're staying balanced with things. I am horrible about eating. Yesterday, I started my day off with a large slice of sea salt caramel chocolate cake. And I was tired, I was working in the emergency room and that huge sugar load just kind of wrecked me and we were really busy and I felt just sluggish, but I also didn't want to eat anything else because now I just had kind of this-- and those days happen and those happen for those of us who should know better and that's applying judgment to it, but that's what we need to help avoid is that judgment.

You're completely right, Tim. We are not going to be perfect. Nobody's going to be perfect. There are some people that are extremely disciplined, but even they have days that they struggle, and you just need to try to have more of the days, be on the good side of the ledger from a health standpoint, when I say good, and a little less on the not as healthy side of the ledger. And the more days you can have on the healthy side, the better off you're going to be.

And the last thing I guess I would add to what we were saying, I agree with shop the outsides of the store, and I agree with look at restaurants that are going to use foods that your grandma or your great, great, great grandma would recognize, and that are having minimal ingredients, with the understanding that that's probably going to cost you more. That's a sad part of our society, is the Cinnamon toast Crunch and the canned vegetables are cheaper than the fresh vegetables and the ingredients to make your meal yourself instead of grabbing it out of the box, or to go to a restaurant that is not necessarily fast food with processed ingredients compared to something that's going to use more locally sourced raised whole foods, as an example, without getting into any specific restaurants. So, it's a challenge because it can cost more. It doesn't have to always, but it can cost more. And it can be a little bit more time to sort through it and figure it out. But it's going to pay off from a health standpoint.

Tim Arnold, MD: I think our society is not really set up at this time to help us make those good choices. I would be a little bit of a contrarian to say that I think that you can go buy whole food sources and do it relatively cheaply but it takes time and it takes effort and it takes thought. You can go buy a bag of whatever vegetable it might be and get it relatively cheaply and have a really cheap inexpensive, healthy meal. But it takes a lot of time and planning and effort, and the way that we live our lives these days, we don't think about our time making food and making meals. You go back, I've read these numbers. I'm going to get this probably wrong, but you'll get the sense of this, that we used to spend a lot higher amount of our day, first of all, procuring the food that we're going to eat for the day. And then number two, planning for how we're going to prepare that and make that food for that day. And now, we spend 30 seconds as we approach the counter at the hospital or the drive-thru at whatever, or the restaurant that we're going into. We pick up a menu and we look at it for a minute and then we decide what we're going to eat. And the whole environment is not really set for us to do that. Going in and out of a gas station and deciding what you're going to eat because you're hungry and you're on the road and you're busy and you've been working 12 hours and so on and so forth, the environment around us is not really set up for us to make those really good choices. Although it can be inexpensive, but it's harder and it takes more time.

One of the best statements I heard about our metabolic health we have in the United States here and really nutrition and all these things we've been talking about is that there's this genetic environmental mismatch. Our bodies were not really made to live in the environment that we live in. Although we certainly could spend the time to make ourselves healthy meals and do it at a relatively inexpensive price, but it's going to shift what we have to do during the day.

Host: And there's many factors that go into that. I would agree with you. You can figure out ways to cheaply have good food. You can grow your own in a garden as well, as an example. It does take more time, and that's the cost. Sometimes it's a cost in money. Sometimes it's a cost in time and planning. It is not set up that easily. There are little tricks. You can focus on almonds or pistachios or peanuts in the convenience store as opposed to a candy bar or chips, for example, but even that's only going to take you so far. But there are at least little ways that you can try to pick things. If you are eating out and you don't really cook, you can focus on some restaurants versus others because you know, one of them is going to have chicken that's been processed and put together, and another one's going to be an actual chicken breast that's not necessarily fried and had a bunch of extra ingredients added to it, just as examples.

Tim Arnold, MD: Last thing is don't forget to be human. Celebrate, have a good time. The emotional part of our lives are really important. So if part of celebrating is to eat, you know, high calorie foods and enjoy that with family and friends, we need to do that. That's part of being a human being.

Host: Yeah. I think, you know, both you and I are fans of Peter Attia. And for any listeners out there, if you have a chance to listen to him or buy his book, his most recent book, we'd recommend it. But there was one of his interviews he was giving not too long ago. I think it was maybe with Andrew Huberman. And he talked about, is it good for him to eat those brownies that his daughter made? Well, not from a metabolic health standpoint, but from a social, mental health, family connections standpoint, absolutely. So, right, it is important to still be human.

Well, thank you again for being on the podcast. Hopefully, we'll get a lot of questions from this one because there's just so many topics. I'm sure we didn't touch on things that people would like to hear about and we can try to address those. The nice thing about having an ongoing podcast series is we'll have a chance to talk about other things or clarify information or bring new information to light as time goes on.

Dr. Timothy Arnold: Thank you.

Host: All right. Thank you very much.