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Dr. Taylor Sittler is the Head of Research at Levels Health, a company dedicated to helping people optimize their metabolic health. Levels provides real-time feedback on how diet and lifestyle choices impact metabolic health through biosensors like continuous glucose monitors. Dr. Sittler is a physician and entrepreneur, previously co-founding Color Health. He completed his residency in clinical pathology at UCSF and started a genetics research group with David Patterson in the computer science department at UC Berkeley.

Dr. Sittler received a Howard Hughes Medical training grant and scholarship during medical school at the University of Massachusetts and UCSD and has published papers on pathogen detection and characterization, genetic sequence analysis and algorithms, and several other topics related to systems biology. 

In this week’s podcast, Dr. Sittler and Sonya talk about defining metabolic health, what you need to consider to be metabolic resilient, and topics like blood glucose, sleep, chronic, and more.

I think the answer is it’s different for everyone. We do find some things that more commonly spike folks. I think the overarching thing that we’ve seen is people typically learn a lot about their individual metabolism when they start to wear something like a continuous glucose monitor. Because we are all so different, I like to say, 50 percent of human variation occurs at less than one percent of frequency, which means your particular enzymes and how they metabolize are quite different from everybody else’s. Just wearing a glucose monitor, getting some kind of feedback, can give you a lot of information about what foods are not good or good for you.

– Dr. Taylor Sittler

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Key Takeaways

  • Defining metabolic health
  • What food is the worst for glucose spikes
  • How sleep impacts your metabolism
  • Tips to blunt glucose 
  • What type of exercise is best for metabolic health
  • Chronic stress’ role in metabolic health


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Sonya Looney: Taylor, welcome to the show. 

Dr. Taylor Sittler: Thanks, Sonya, great to be here.

Sonya: Well, it’s so much fun to get to talk to you because we’re both passionate about health and performance. And I think that, like psychological resilience is something that we talk a lot about on the show, but biological resilience is maybe a topic that hasn’t been covered in great depth. So can you tell me what you mean by biological resilience?

Dr. Sittler: Yeah, definitely. So when we think about health, we don’t really have a good definition for it. Most of the time you go to the doctor, and your doctor is checking to see if you have all different kinds of diseases. I think we need to flip that and think about how we can evaluate health. And this is a trend, I think that’s going on more broadly now. I think there’s in functional medicine, in a number of different sort of corners of medicine, we’re starting to see people get interested in measuring health. And resilience, actually, in psychological sense, was actually one of the first endeavors to try and measure health in a way. It’s been measured in a number of different ways, historically, mostly through psychology or psychological metrics. But really, the things that tie those different methods together were a stressor and an adaptation. So there was something that really perturbed the system psychologically, usually, it’s some kind of a trauma. And then there’s an adaptation and an ability to handle that stressor over time. And that mechanism, that kind of concept applies very well in biology, and particularly in areas like metabolic health and when we start looking at continuous monitoring. So when we start looking at biomarker measurements over a period of time, what we can see is that there are very specific adaptations that the body goes through with particular stressors. And I’ll give an example of resilience, which might be metabolic resilience, or biological resilience, can be measured by giving someone a slug of glucose, like in an oral glucose tolerance challenge. And the body’s response to that, the height of the glucose spike that occurs and the duration of that spike, are proportional to the body’s resilience. A longer spike and a higher spike are indicative that of a condition of insulin resistance, and potentially, eventually of diabetes, if the system is very out of whack. But resilience, really, in a biological sense. It’s a stressor applied to your body, and then an adaptation that can be measured.

Sonya: That almost sounds like training too, like if someone’s out running or riding their bike, and you’re applying a stressor, and then you’re adapting to that. And it’s all about how you adapt and then coming back stronger.

Dr. Sittler: Absolutely. So I was on a podcast with Zach Bitter a couple of weeks ago and we started talking about this in the context of his endurance training. And what he was saying was, for instance, with his heart rate, he would run some set number of miles and check his average heart rate. And then he would train that same number of miles week over week and see a downward trend in his heart rate. And I think that’s resilience in action. Right? I think athletes are used to thinking in these terms all the time. I think it’s one of those things that the general population hasn’t yet adopted. And we use resilience clinically, so there’s an oral glucose tolerance test, there’s a cardiac stress test that a cardiologists will use. So physicians have started to use this clinically for a while. It’s just not sort of in the general circulation yet. And now that we’re doing these, now that we’re able to monitor things continuously, like glucose heart rate, we can actually do resilience measurements all the time.

Sonya: I think that’s something that’s important to note with resilience is that we are able to change and it can change in both directions. But I think that a lot of times you’re talking about the general population, they just think like, oh, that’s just the number and I can’t fix that number; that’s just how I am. But in terms of, you know, glucose and metabolic resilience and fitness, what are some things number one that you’re looking at? You mentioned glucose, like people just might not be really familiar with what is, you know, continuous glucose monitoring? What is metabolic health? What is a metabolic problem? So can you go into that direction?

Dr. Taylor: Yeah, definitely. So metabolic health is, you know, it’s important for us to also get into the state of metabolic health of the country, which is pretty poor. But metabolic health is really the health of your system, your metabolism. Every single cell in your body burns energy in the form of either glucose or fats, and it can switch or most cells can switch between those two forms. Metabolic health is how well those cells are performing with those energy sources. So there are three main organs that are involved in making sure that there’s an adequate level of energy in your body at all times. Those are liver, your fat, and your muscle. And those three are involved in this intricate kind of dance, to make sure that that glucose and fat levels stay fairly consistent, so that all of your cells are able to function. Cells need to be able to burn energy in order to live. So they burn energy, produce ATP, and that allows everything to happen in your body. And that your state of metabolic health is really determined by the ability of your cells to process that energy and the ability of your body to provide that energy at a stable level.

Sonya: So what would it look like if somebody wasn’t metabolically healthy?

Dr. Sittler: Yeah, well, you don’t have to look very far because some recent papers have suggested that roughly 93% of the US population has at least one marker of metabolic disease. So metabolically healthy folks are actually far rarer than metabolically unhealthy.

Sonya: 93%, that’s like almost everybody.

Dr. Sittler: And this is really due to the type of food that we’re eating and the type of food that we have been eating for the last 20 to 30 years, or even longer, I would say. In the 1970s, we started subsidizing wheat and corn production in the US, which ultimately resulted in a lot of high fructose corn syrup being produced. And now we see tons of refined carbohydrates and refined ingredients in the foods that we eat. And that has massively impacted our metabolisms. First, it’s overloaded us with with mostly sugars, and starches, and that results in insulin resistance, which is intimately tied to metabolic health. And so someone who’s metabolically healthy, I would say, is able to handle a pretty large meal of any kind, with an appropriate insulin response, and then dropping the sugar level in the bloodstream fairly soon after the meal. Someone who’s metabolically unhealthy, may end up with an elevated sugar level in the bloodstream for a prolonged period of time. And we call that insulin resistance because usually starting with the muscle, there’s no response, there’s an inadequate response to pulling that glucose into the cells and removing it from the bloodstream.

Sonya: So we’re primarily focusing on glucose and how long glucose is potentially out of range and how quickly it comes back down. You mentioned food as one of the primary ways that are contributors to health or lack of health. And you mentioned refined carbohydrates. And I’m just putting this out there for the listener because carbohydrates have been demonized so much. And I’m glad that you said refined because people just put all carbohydrates under one umbrella. Can you, for the listener who’s unsure, can you define more specifically what is the problem with refined carbohydrates in terms of metabolism?

Dr. Sittler: Absolutely. I mean, I think fundamentally, our bodies have evolved to eat food, right? That’s food that you pick from a tree or from a root or something in the ground, right? Fruits, vegetables, things like that. And many of those have carbohydrates in them, but they’re typically mixed with fiber, with protein, with fat, in ways that your body can handle and doesn’t get overwhelmed by what has happened in the past 50 years is we’ve learned how to fractionate components of food very well, in ways that your body doesn’t do well with; it’s not able to respond well and you basically get this overload of calories. So any kind of ideally organic, but fruits, vegetables, again, things that are sort of grown in the ground, typically your body responds quite well to. Unfortunately, though, if you go into the supermarket, those foods are on the edges, and most of the stuff that you see in the middle is packaged. And as an experiment, I went into I think it was a 711 must have been five or six years ago and just started randomly picking stuff up to see you know how often high fructose corn syrup was present. High fructose corn syrup in particular is bad because high fructose corn syrup for a number of reasons causes the liver to accumulate fat, and is particularly bad for the body in terms of inducing metabolic disease.

Sonya: So we don’t want to eat processed foods, we want to eat our carbohydrates as close to form as possible when they come out of the ground or they’re picked off at the plant, because it still maintains fiber and proteins and some of the other nutrients that will help blunt the spike and also have other nutritional benefits. 

Dr. Sittler: Exactly, yes. 

Sonya: What are some foods that people might not realize? Like we talked about the refined carbohydrates and high fructose corn syrup, but what are some other maybe more insidious foods that you’ve noticed spike people’s glucose and contribute to, you know, maybe less than ideal metabolic health?

Dr. Sittler: Well, so that’s a really interesting question. I think the answer is, it’s different for everyone. We do find some things that are that more commonly spike, folks. But I think the overarching thing that we’ve seen is, people typically learn a lot about their individual metabolism when they start to wear something like a continuous glucose monitor. Because we are all so different, I like to say 50% of human variation occurs at less than 1% of frequency, which means your particular enzymes and how they metabolize are quite different from everybody else’s. So just wearing a continuous glucose monitor or getting some kind of feedback can give you a lot of information about what foods are not good or good for you. Some of the biggest offenders that we see are Pop Tarts, for instance. They tend to spike a lot. Not surprisingly, but but that that particular tag, because in the Levels app, you can actually tag what you’re eating, and then we’ll correlate it with the glucose spike. So that one I think, is the most common, the most, the biggest offender. Some other ones that we see very frequently are things like oats, which people think are healthy, but actually do result in quite a bit of glucose rise in the bloodstream. And I would say, you know, pretty much any kind of a refined starch or carbohydrate, and particularly drinks that have high sugar content, it turns out, you can drink calories much more quickly than you can eat them. And oh, sorry, one more piece about the high fructose corn syrup. When you take in calories from fructose and from high fructose corn syrup, there are certain hormones that indicate that you’ve taken in enough calories and and it’s their satiety hormones. And those hormones are, they don’t function as well when you take in large volumes of high fructose corn syrup, as opposed to something like, you know, like honey, or some sort of a more natural sugar.

Sonya: Yeah, I was actually going to ask you about some of the fake sweeteners or like the sweeteners that don’t have calories like Stevia? Like, how does that impact glucose, if at all?

Dr. Sittler: Yeah, that’s a good question. I mean, most of those are actually designed to not be taken up in the intestine, so they don’t go across the intestinal wall. Some people have, I think we have seen some shifts in glucose. It’s not clear exactly why I think some of these things can be partially metabolized in the gut. And then there’s some idea that there’s there’s some other mechanism of action going on there where there’s, you know, I can’t say for sure, but most of these are designed essentially not to go across the intestinal wall. So for most of the artificial sweeteners that are out there, you wouldn’t necessarily see a glucose spike. But it’s not clear that, like, I think, with some of them that more testing is really going to be needed to know whether there are other effects that negatively impact you in terms of your health. I think that the safest thing to do is really just again, to eat food. Yeah, eat real food, is really what it comes down to.

Sonya: Yeah, so I’ve used a continuous glucose monitor and had it paired with levels a couple of times and gotten some interesting data for myself. How often are people supposed to be, you know, testing this because you where the monitor, I think it lasts for two weeks? Is it something that that people should be wearing all the time? Is this something people should periodically check like every few months, like what’s recommended here?

Dr. Sittler: Yeah, well, I think there’s definitely no recommendation. So far, I think we’re learning a lot about the use of continuous glucose monitoring in the general population. And we at Levels just launched a large clinical trial looking at this. So we still need to establish what the ranges are and what the utility is in the general population. I think it’s much better described in type one and type two diabetes, but we’re really learning a lot right now. I mean, I can tell you what I do. There’s a range at the company. Some people wear it all the time. Others like me, I’ll wear it for two to four weeks, and try to optimize and improve my diet and improve my glucose control, reduce the number of spikes I have, and then I’ll stop for a little while, and then I’ll pick it up again a month later. So I actually will do two to four weeks and then take a one to two month break, and then do another optimism, I call them sort of optimizations. And I’ve learned something typically with each optimization. But I think there are a number of things that once you know them, you can take with you beyond the everyday continuous glucose monitoring.

Sonya: The personalized medicine piece of this, I think, is really interesting. And just in general, how there’s a lot of data available to the general public so that they have autonomy for you know, taking control of their health. And one of the main elements of motivation is autonomy and feeling like you have some some sense of control, instead of just reading some numbers, if you maybe get a blood test, maybe even get a copy of a blood test, which is just a snippet in time and isn’t even a continuous thing. So being able to see what you’re eating or even how other life stressors are impacting your metabolic health is really cool and really empowering. But I also wanted to ask about, you know, what if people are getting repeated low numbers, or maybe they think they’re healthier than they are, like, I bet a lot of people listening are, you know, athletes or people that prioritize their health and might be surprised that maybe that number isn’t as high as they think? How have you guys as a company thought about people dealing with feeling discouraged about what the results might be?

Dr. Sittler: Yeah, well, we’ve taken a very close look at our product. And we’ve actually started updating it. So we used to have this idea of a metabolic score that we gave everyone each day, that gave you some indication of how things went for the day. And we found exactly what you’re talking about, right? People would get discouraged if for some reason, they were not able to increase their score, or, you know, they couldn’t figure out how to get a good score. Because the parameters for that score were not very clear. We’ve moved away from that kind of messaging, and from the idea of a one definitive score. And what we’re starting to move toward are identifying wins, and identifying ways that people can improve. I mean, where we started was this idea that you resilience can change, right? And it really can, I think, you know, even if you’ve sort of had insulin resistance for a long time, or if you are far down this track of elevated glucose, you know, you did your lipid panel, let’s say, and it was sky high, those things can actually change. And in some cases, they can change pretty quickly, with the right interventions, basically, with with the right monitoring, and the right follow up. And a lot of it has to do with diet, with sleep, with exercise, which I think exercise actually shows the best correlation with long term health span. So these things can change quite quickly when you apply yourself.

Sonya: I’ll ask a loaded question about diet. I eat a whole foods plant based diet I’ve had Dr. Casey Means on the show is probably a year ago, and we talked I don’t know, I haven’t talked to her since then, so I’m not sure what she’s currently saying, because people are allowed to change their minds about things. But what type of diet? I mean, you’ve mentioned eating real food, but is there a type of diet in particular, or just a way of eating that is better for your metabolic health then not?

Dr. Sittler: So Casey’s definitely more of a diet expert than I am. So I will defer to her. And she does talk extensively about this. She talks a lot about avoiding refined, refined carbohydrates, eating real foods, avoiding pesticides. There are these new compounds that we’re finding called obesogens, which may contribute to encouraging the body to take in too excess energy, effectively, things like sleep, and then light, which impacts your sleep cycle. Those were kind of the main things that she mentions. And I think that makes sense. If I had to be particular about it, I would say, you know, if I look across the literature, the diets that have been associated with the best outcomes that I’ve seen are ketogenic type diets. But I think where we try to be careful about that is it’s really, it’s not removing all carbs and just adding fat. It’s removing refined carbs, particularly, and eating a healthy diet overall. So I think that’s really the message and what I think Casey promotes these days, and I agree with that.

Sonya: Okay. You talked about some non food related lifestyle things that people can do to improve their metabolic health. You mentioned sleep as one of those. How does sleep impact your glucose? Because I think that might be a disconnect for a lot of people.


Dr. Sittler: Yeah, no, it’s really interesting. So sleep there, we’re showing that even one night of inadequate sleep can impact your metabolic function. So glucagon and insulin work together to help you manage your sugar. And people that have had a poor night of sleep have higher levels of insulin, they have higher levels of glucose in their blood, and they have evidence of more insulin resistance than those who have slept well. So there’s a correlation between development of insulin resistance, and lack of sleep, and there’s also a correlation between changes in glucagon levels and lack of sleep. So lack of sleep has a pretty profound impact on the hormones that help you manage metabolic health.

Sonya: Is there a minimum threshold? Or is that dependent on the individual?

Dr. Sittler: I don’t know that we have…his is where I would love to have continuous monitoring of everything, right? I think that’s what we’re going. We don’t we don’t yet know, because people aren’t really measuring these things in real time. The hormone that has been measured most in real time is cortisol. And cortisol has a natural spike in the morning. We know that when people don’t sleep well or let’s say you had an all nighter, you slept from 4am to noon, your cortisol may bump up at noon instead of at 6am when it normally bumps up, right? That’s the normal diurnal cycle is for it to go up early in the morning. If it bumps up at noon, now you’re shifting your insulin resistance and sensitivity at different times of the day and it has an impact on your glucose level. You know, we don’t know yet. We don’t know yet. But but we know cortisol, glucagon, insulin, a lot of the hormones that are involved in metabolic health are impacted.

Sonya: I was thinking a bit about like circadian rhythms and jet lag, or shift work or like those types of things. Yeah. How can you use, like the Levels app to potentially maybe have better experiences when you’re traveling or if you’re doing shift work to like mitigate some of the issues with that.

Dr. Sittler: So the the Levels app is starting to help you avoid glucose spikes, or at least identify them. And I would imagine folks that are on shift work,are going to have higher glucose spikes because they’re more insulin resistant. So just being able to monitor that and try to improve that could go a long way toward improving people’s metabolic health. So I’d say that’s the simplest way to do it is to just wear the device while you’re on shift work, and to see which foods you’re eating and maybe at what times you’re getting these different spikes. And there, there are swaps that you can make to reduce the glucose level with a particular meal. If you eat protein, or you eat some fat prior to eating the starch or glucose portion of your meal that can help. We’ve seen a lot of people improve their glucose by walking after they eat. So for instance, if your glucose starts to go up, and you’re able to get out and go for a 20-30 minute walk that can often stabilize your glucose quite quickly. So those are ways that you can use the app on shift work. Jet lag is a little bit trickier. And I think, you know, this is still very much tentative, but there’s some tantalizing data that kind of changing your sleep cycle and changing your eating cycle to your destination can help you reduce jet lag. So for instance, if you’re going over a six or a nine hour timezone change, one of the things that we’ve been experimenting with internally is not eating for, say, 16 hours, and then having breakfast at the destination. And it turns out that in addition to the light, which is a primary determinant of your sleep-wake cycle, food availability helps determine your sleep wake cycle and your circadian rhythm. So by resetting when you eat, you can actually more quickly adjust. And, you know, we’ve, these are all anecdotal results so far, but we have had a few folks who have been able to fly halfway around the world and have reported much less jet lag after doing this type of intervention.

Sonya: I’ll add another anecdote to the pile here, which might be a little bit surprising. So I used to travel a lot internationally for racing. And I haven’t done as much since you know, the pandemic and having two little kids snd I’m excited to be returning back to international travel, hopefully next year when I’m not breastfeeding anymore. But I was always trying to figure that out. And I would notice it, especially around that, that eight hour mark, like going to Europe, I would go there and it was like my cortisol or my nervous system just wasn’t working properly. Like I would go out for a ride and I couldn’t get my heart rate up. And it was like there was a governor just preventing me from being able to rise to the occasion. So I was doing everything I could try to figure out this jet lag thing. And so I decided to try acupuncture, and someone’s like, try acupuncture, and I thought, well, okay, I’ll try acupuncture. So I went, and it did this miraculous thing, it worked. Like I went, I had almost no jet lag, I was able to push myself and then I tried it repeatedly, and it worked repeatedly. And I asked the acupuncturist, I said, I know that there’s there’s there’s lots here that I don’t understand, but can you tell me roughly what you’re doing? And basically, they said that they were stimulating the organs of digestion, to try to be on the same clock as where I was going. Oh, that’s really very similar to what you just said, but it was through like, yeah, acupuncture.

Dr. Sittler: This was acupuncture you were doing at the destination you were?

Sonya: it’d be Before I left, they would be Yeah, they’d be like trying to set my clock essentially to, you know, my digestive clock to what it would be like at the new destination. So I thought that was really interesting. And then now you said that so I’m like, well, maybe there was something to that.

Dr. Sittler: That’s really interesting. Yeah, I can’t comment on acupuncture. But it seems like, you know, the resetting it with food can be really helpful. So yeah.

Sonya: So I want to move on to talking about exercises, that’s something that you said can really help, you know, with glucose. And there’s different types of exercise or I mean, you mentioned walking, brisk walks are great. And you know, people don’t have to be doing ultra marathons in order to be healthy. And in fact, ultra marathons might not be healthy for some people. 

Dr. Sittler: Yeah, there’s a lot of data to suggest that. Yeah.

Sonya: So in terms of training, is there like a better than option like strength training, endurance training? What’s what’s the best for your metabolic health? If there is a best?

Dr. Sittler: Yeah, I think both types are good. If I had to, what I’ll split it into glycolytic, or anaerobic versus aerobic, right. And this is like powerlifting, strenuous exercise, strenuous strength training, versus zone two, or aerobic going for a run, a walk, things like that. And actually, both are helpful. And both are actually required, I think, for a healthy body. I mean, what’s interesting is they’re different effects on the continuous glucose monitor. So for strength training and strenuous exercise, we typically see a rise in glucose. So for instance, when I go to a CrossFit workout, my glucose will go from 90, let’s say, up to 170, or 200, that’s milligrams per deciliter. If I were to do a longer walk, or a very slow run, slow jog, let’s say in my zone two usually between like 120 to 140, then I often will see a drop in my glucose, as my slow twitch muscles are spending more time burning fat, and they’re working aerobicly. So both of those things are super helpful metabolically. And, as you know, both are required for fitness, if you want to be any kind of an endurance athlete, and, you know, most types of athletes in general, because those two types of muscle help each other out. But what’s interesting is how the CGM changes with one versus the other. 

Sonya: I wanted to ask about body fat because there’s an assumption that if you are overweight, then you are probably metabolically unhealthy. But if you don’t have excess body fat, you’re not overweight or obese, can you still be metabolically unfit? 

Dr. Sittler: Yeah, well, if this paper that came out this past summer is correct, then, many people are unfit. Yeah, I mean, that’s, that’s a lot of people. So I think because of the diet that we consume, as a country, many of us are unhealthy metabolically. What we see is, over time, a lot of the results of unhealthy eating are calorie overload. And that can result in varying degrees of weight gain, depending on the individual. But you know, there are a lot of individuals who seem healthy, otherwise, who wouldn’t if you were to do a number of laboratory tests, you might find out that they’re not. A lot of these people have insulin resistance. So their fasting insulin level will be high, or they have some other marker of metabolic disease, which is things like blood pressure, etc.

Sonya: And how does chronic stress play into all of this? Because I think that, especially with the last couple of years, a lot of us have experienced probably higher levels of stress and maybe weren’t even able to, and still maybe aren’t able to do the things that they used to do to relieve that stress. How does chronic stress play a role in metabolic health?

Dr. Sittler: Yeah, that’s a great question. We think that I mean, this is still very controversial, because it’s been hard to measure. But one of the hormones I was talking about earlier, cortisol, typically stays elevated longer in people who are under chronic stress. And we know that that is associated with overall increasing fasting insulin and insulin resistance, which is then likely to result in an elevated glucose and make you sick over time. So we know that there’s a correlation between the hormones that are involved in chronic stress and metabolic disease. So what is happening in societies, there’s this confluence of events. It’s the food that we’re eating, coupled with the stress that we’re under, coupled with the fact that we are not exercising, which is just overloading our bodies. I think if it were any one of those individually, we probably would be more resilient, not to use the word incorrectly. But I think the confluence of those things, particularly diet and stress together, and lack of exercise, are really making people sicker.

Sonya: Have you seen any stress relieving activities that have made an impact on that score, holding diet as a constant?

Dr. Sittler: We haven’t been able to do studies that specific yet. I think that the interesting interventions that we’ve seen for chronic stress are things like mindfulness, breathwork, which is really interesting. So, you know, these short even, you know, 15-minute breathwork exercises with rapid inhalation, exhalation, and breath holding, seems to reset the sympathetic nervous system. And there is some evidence that can improve the stress hormones. You know, there’s one other thing that I didn’t talk about one other intersection between diet and disease, nd that is there’s, over time, chronic inflammation develops. And inflammation is another thing that is exacerbated by chronic stress. So our bodies have evolved to when we underwent that fight or flight response out in the wild, we were getting ready for potentially for combat, right. And so your body in a fight or flight situation will actually ready the arm of the immune system that deals with puncture wounds. It’s the innate immune system that can help fight off bacterial infections. Turns out by enabling that arm and shutting down the more adaptive arm, we’re essentially reducing…Well, first, we’re promoting cardiovascular disease, because macrophages are intimately involved in the development of plaques and cardiovascular disease. So chronic stress promotes that. And then we’re simultaneously reducing our ability to do cancer surveillance and things like that. So the immune cells that are involved in that tend to be downregulated in stress and chronic stress. And so that puts you at risk for a whole other set of diseases. So that this interplay between the inflammatory state and your insulin resistance, actually is also really important for the development of disease. And that’s another reason why chronic stress is so important to be able to deal with.

Sonya: Ss you’re speaking about that I was thinking about people with type one diabetes who have you know, insulin problems, but have to regulate it. And can they do anything with their lifestyle like that, like using breathwork or reducing inflammation that help? Or are they just sort of hooped?

Dr. Sittler: No, not at all. I mean, we’ve I’ve talked with several nutritional counselors and physicians who have helped lots of people with type one or type two diabetes, I just want to make the disclaimer here that Levels isn’t really designed to help folks with diabetes, it’s designed more for the general population. But there are programs that have been really successful in helping people with both type one and type two diabetes to achieve better metabolic health. And I think one of the things that many of them will tell you is that a good exercise regimen, for instance, can really help put glucose in check, because it sensitizes the muscles in the interior, so people have to take less insulin.

Sonya: I’m kind of jumping around, I’m jumping back to exercise. So we’re talking about inflammation, and exercising too much can actually cause excess inflammation in the body if you’re doing too much. So and I’m assuming that impacts your immune system, and you were talking about the interplay of the macrophages and what was the other part?

Dr. Sittler: And the the adaptive arm of the immune system? You know, I think damage following exercise is a really interesting one. I’m not super familiar with the literature on that. But my guess is the type of tissue damage that occurs and the follow up response is very different from the type of activation you get with stress and with chronic stress. I mean, I don’t really have a good basis to come in. But I don’t have any reason to believe that the inflammation that follows tissue damage from exercise puts you at higher risk for metabolic disease.

Sonya: Okay. And you mentioned high blood pressure and how chronic stress could contribute to higher blood pressure. Why does that happen?

Dr. Sittler: Yeah, so that’s actually quite controversial. Actually, when in going back and looking at the literature, I think there’s a more a more well established correlation between food and blood pressure than there is between stress and blood pressure. We know that the, you know, epinephrine is, so epinephrine is one of the primary hormones that’s released in the fight or flight response. And that causes your heart rate to go up and it causes your arteries to constrict. So that’s an immediate vasoconstrictor and will cause your blood pressure to go up immediately. Now what that whether that keeps your blood pressure high, or maintains blood pressure at a higher rate is still very controversial. But that’s a plausible mechanism under stress. In a dietary sense, so if you’re eating too many refined, refined carbohydrates, for example, the elevated insulin levels that will be in your bloodstream can both cause a change in the kidneys salt retention, which can increase your blood volume and increase your blood pressure. And you can also see there’s also a direct action of insulin at the what’s called the endothelial lining, the inside of the cells, that changes the tension of the vessel through nitric oxide. So there are those two mechanisms by which insulin can impact the blood pressure in the body.

Sonya: One of the main reasons that I started eating a whole foods plant based diet like 10 years ago was because everyone in my family would get high blood pressure as they got older. And I was like, wait a second like this, I don’t believe this is going to be genetic. Like this can’t happen to me. And we’ll see what happens, but that was a primary reason was diet. But I’ve been thinking about other things that impact blood pressure because having high blood pressure isn’t good for you. So we’re talking about stress, we’re talking about breath work. And I don’t know anything about the literature, how stress or breath work can improve blood pressure, but it’s just been on my mind.

Dr. Sittler: Oh, yeah, no, interesting. I mean, yeah, I don’t know that there’s a great correlation, we still need to do more studies. And it’s hard to get people to do studies on interventions like breathwork, because there’s no pharmaceutical company behind it, right? There’s no, there’s no payer that’s willing to do these, these large clinical trials. I have found personally that I can actually change my blood pressure through just inhaling and you know, holding my breath, and then exhaling. I can drop it by a good 10 or 15 points. Oh, wow. Yeah, you should try it. If you have a high blood pressure monitor. Yeah, just just take some deep breaths, and play with it a little bit and I think you’ll find that you can actually reduce your blood pressure quite a bit. I mean, this is another anecdote, I don’t think we can make much of it, but it’s kind of funny. I had high blood pressure when I was in my residency. And, you know, obviously, it’s a fairly high pressure environment. But what was really interesting is I had to get on medication for it, I was on a fairly high dose of lisinopril. And actually, when my residency ended, and then my roommate moved out, my blood pressure went back to normal, and I could get off the medication. You know, there, it’s very anecdotal. And I think, you know, blood pressure, particularly in young to middle aged adults can be very labile. So there are a number of factors that influence it. But yeah, I think there are also a lot of things to that same point that can change it.

Sonya: So do you have any professional athletes that are using Levels during sport. Like I think that the UCI might, I think it might be illegal to have a CGM in while you’re racing and to be using it. I can’t remember. I thought I heard that. But have you been working with athletes so that they can make better nutritional decisions while they’re exercising?

Dr. Sittler: Yes, both internally, we’re working with a couple of athletes, as well as sponsoring studies for athletes. And there’s a really interesting paper that I can’t talk too much about that’ll be coming out soon showing that by changing a diet, you can actually achieve great, well, you know what, I’m not going to say it because I’m not sure what they want. They’re one of our good external collaborators and they’ve done some fantastic research on basically the diet that an athlete would can consume, and the performance they can achieve. And I think it’s, it’s, you know, what we’re seeing more and more, and this isn’t just from this study, but there are a number of studies now, showing that you can achieve great athletic performance and still have manageable blood glucose. I think what happens with a lot of athletes, is they will carbo load for various reasons. And that can actually cause pretty, pretty massive glucose spikes. And you don’t necessarily, you don’t need to do that, in order to perform well. Now, there are obviously certain activities that that will require it if you’re doing, you know, CrossFit Games or something like that, you may need to, you know, there are different strategies that people employ. But I think what we’re seeing is, in general, you can both maintain good glucose control and good performance.

Sonya: I imagine that it’s one of those it depends questions of, you know, what is the intensity? What is the number of days in a row that you’re doing? Because there’s the muscle and liver glycogen depletion that needs to be replaced, but then maybe people are over replacing, what they’re what they’re using. 

Dr. Sittler: That’s right. And it’s easy, it’s quite easy to do that, right. Given the substances that are now available to us, we can take in glucose at a phenomenal rate. I mean, I only have to drink a can of coke to see that. Right. And, you know, there are lots of specialized little Gu shots or whatever you use for different types of endurance and performance athletes. So I think ,you know, one important thing, you don’t have to do this during a race, but as an athlete, it might be a good idea to just check your glucose for a couple of weeks during your training, and to see if you’re having major glucose spikes, because I think the data is showing us is that you can cut out those glucose spikes and still achieve solid athletic performance.

Sonya: Something interesting that I found when I was using it, because I would check it like okay, I feel like my blood sugar is dropping on my bike. So I would stop and scan the CGM, and then look, and then see how different sport nutrition products would impact my blood glucose. And that was interesting to see that, like fig bars, made it spike up the worst. And I was really surprised by that. Because like there’s a little a little bit of fiber in there. But there I didn’t look at the ingredients that might be like added sugar in there too.

Dr. Sittler: Oh, for sure. I wouldn’t be surprised if there isn’t just a little bit of high fructose corn syrup in there too. But maybe not. It depends on the brand that you get. But I think just thinking about the outside of those, right there’s there’s fig in the middle, which is already like if you look at fruit, fig and date have the most sugar and fructose in them. And then if you add the refined carbohydrates that’s in the shell or on the outside, that’s probably a pretty good one two punch.

Sonya: Yeah, yeah. So I think that just talking about some of the these things is going to spark interest with some of the listeners have like, well, curiosity here, like, I wonder, you know, what I’m like, and how I can get better. And that’s why I was using Levels. And I want to do it again, now. Offline, we are talking a little bit about like lactate and ketones. Is that a direction that Levels is looking at? And is that something that could be tested continuously, like glucose?

Dr. Sittler: Well, what’s interesting is we’re seeing a lot of companies start to develop other metabolic monitors. So there are several ketone monitors. Most of those use breath ketones. Abbott announced this year that they’re developing lactate, as well as alcohol monitoring, which is interesting. There are a couple of alcohol sensors that have come out recently. So people can start to measure their blood alcohol, or their interstitial alcohol levels. So yeah, I think there’s a lot of interest in this. What’s interesting about adding things like lactate or ketones, is that you can start to get a more full metabolic picture. Glucose is really at best, you know, maybe 10% of the puzzle. Ideally, you’d be able to measure insulin, which is actually quite hard for a number of technical reasons. But I think in the near term, we’re going to see a lot of work on ketones, lactate, probably different sensors that can measure some form of free fatty acid, or a proxy for free fatty acid. Because we were talking about the fact that cells can metabolize both glucose and fat. And, you know, right now, we’re really only looking at one side of the equation, and trying to infer fat burning from what we see in glucose. It would be much better to be able to measure both simultaneously. And there are a few devices out there that can do that now, but it’s, they’re not generally available. And there aren’t, I think, good apps that can help interpret the data for people, which is really, I think the most important thing is to be able to give people insights and put them into context.

Sonya: Yeah, because most people are not medical experts are not new. They’re not dieticians, and knowing how to make sense of data is such an important part of how do you take action. And if you don’t know what actions to take, you just feel helpless. And that’s not a good place to be at all.

Dr. Sittler: Yeah, no, 100% agree and that’s very much the company’s philosophy, we try to make this data accessible and understandable for people. And it’s taking the guesswork out of it, enabling people to get insights that they can use to improve their health. We talk a lot about this concept of interoception. It’s something that that I think intuitively makes sense. But it’s kind of how you feel, knowing how you are by how you feel. And what I think glucose adds to that, and what hopefully, you know, these other markers will add more of, is the ability to sense how you were doing internally. And more than just a gut feeling of I have energy, I don’t have energy, you know, I’m feeling high, I’m crashing, I’m sleepy, I’m not. We can start to look at the actual data, and we can look at your metabolism. And I think that mirror that people are able to look at will be really helpful in improving their health.

Sonya: I was just thinking about knowing how you feel versus looking at a number and I think you need both. But the other side of it is like people will look at the number to be like, okay, how do I feel like HRV is a prime example. You know, they’ll look at their HRV in the morning and be like, oh, it’s low. I’m gonna feel bad today. And then they just end up feeling bad today, because they decided they’re gonna feel bad today, you know, versus saying, well, how do I actually feel because sometimes you can have a low HRV and still feel really good, but not letting the numbers get in your head and mess with you.

Dr. Sittler: 100 percent. Yeah, I didn’t mean to imply that. I think interoception is very much a holistic thing. It’s how you feel plus interpretation of the numbers, right? 

Sonya: I think that’s exactly what you were saying is that it’s not just about this number. It’s about really knowing how you feel.

Dr. Sittler: Yeah, yeah. And abstracting away from the number a little bit like, you know, we were getting away from just looking at your glucose level or just looking at your metabolic score or just looking at your HRV right. I mean, you know, I use Whoop for a while and I think we all have days where we get up and Whoop is telling us we should have had a great night’s sleep and we feel terrible, right? Or vice versa. So there isn’t a there’s, there’s generally not a direct match between any one number and your overall feeling. So it’s important to trust that intuition. And then to put the numbers into context.

Sonya: Yeah, like health and performance isn’t reductionist, but it’s just about knowing yourself, and then just trying to do the best that you can with the information that you have. 

Dr. Sittler: Yes, absolutely. 

Sonya: So where can people find levels? And if they have more questions, where can they find more information,

Dr. Sittler: The product is now generally available, so you can sign up right on the website, we’ll ship the CGM to you and we have an app. We don’t make the CGM, we just provide them through third party. And we make the app to enable people to interpret the data. I think one other resource that I would like to call out is the blog. So We’ve made a real effort. And I think the team has done an excellent job of creating educational content that’s not biased. We’re not trying to get people to buy CGM. What we’re trying to do is help people understand metabolic health and how it impacts them. And I think the team has done a really great job of covering all the issues related to metabolic health, and how these might impact you.

Sonya: Yeah, I spent some time on that blog. And also in the app, there’s recommended, you know, reading and I think that that education piece is really cool.

Dr. Sittler: Awesome, thanks. Yeah, we’ve been working hard at that. I have to give the team a lot of congratulations there.

Sonya: Well, thanks so much for coming on the show. And hopefully after listening to this, people are more curious about their metabolic health and taking action to be their best self.

Dr. Sittler: Absolutely. Thanks for having me, Sonya.

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