Continuous Glucose Monitoring with Dr. Casey Means
In this episode of the Next Level Human Podcast, Dr. Jade Teta speaks with Dr. Casey Means of Levels to understand how the right diet and lifestyle can help us tap into our full human potential. Dr. Means covers why diet is just one puzzle piece of overall heath, why sugar and carbs are the enemy, and how health is a personalized journey.
People want to optimize their life
Americans may be unhealthier than ever before, but they are also more eager to be healthy than ever before. Continuous glucose monitoring helps make that possible.
Over 50% of Americans are trying to go on a diet to lose weight each year. What does that say to us? That people are trying, people want to do better with food. People want to optimize their diet and lifestyle for better outcomes, and so to actually now have a tool that can give us objective, real information and not just hearsay, not just maybe the number on the scale the next day, not a cholesterol test six months from now, but immediate. “I eat this,” and 15 minutes later, I have some feedback about whether that was really serving my goals or whether it might not be the best choice for me. I think that’s going to give people a lot of empowerment.
A bagel isn’t just a bagel
A single food can create multiple metabolic responses in two different individuals.
You and I very likely could have a totally different glucose response or glycemic response to that bagel. That’s because the bagel is interacting with this complex organism of different amounts of muscle, different level of insulin sensitivity, different microbiome, different micronutrient status, different sleep and exercise the day before or the day of the bagel. All of these things can factor in to that process of converting that bagel in the mouth to glucose in the blood being different. That has really large implications for our health, because if I get a gigantic glucose spike, if my body and my physiology converts that bagel into a quick release of glucose in my blood stream, that’s going to have a different physiologic cascade to you if the bagel causes a very, very little glucose rise in your blood. When we get these large glucose excursions, these big, quick peaks after meals, that’s not great for our body over time.
True health takes more than diet
Total health includes diet, lifestyle, sleep, stress, and physical activity.
Diet is necessary but not sufficient for optimal metabolic health or optical glucose control. You can’t have perfect metabolic health or glucose control if your diet is off the rails, and tons of refined carbohydrates and sugars, but that’s a loan, that’s not the panacea. You also need to dial in these other factors about our health, our diet and our lifestyle that have a really strong impact on insulin sensitivity and glucose levels. Those things are really sleep, how much sleep we’re getting, the quality of our sleep, stress, so how we’re responding to stress, how much chronic low grade stress that we’re under, the acute stressors in our lives, and then physical activity, for sure. That’s a gigantic one. Those are the three modifiable activities each day that we can really dial in to have optimal metabolic health.
The impact of stress and low sleep on the body
Dr. Means has noticed firsthand how her glucose levels tend to spike with increased stress and too little sleep.
I also noticed that on days when I’m just chronically a little bit extra stress, something’s going on with work or with personal life or whatever, my glucose often just phase shifts up. My baseline is around the eighties, and then after a meal, it’d go up to 95 or 100. I might see that it’s just always up at 90 that day. It’s starting at 90 and going up to 120 after meals, and so it just feels like it phase shifts it up. I don’t have any evidence to support that, it hasn’t been shown in the literature that chronic stress leads to a baseline elevated glucose like that. But I’ve noticed it in myself, and the same is true with sleep deprivation. If I get, for whatever reason, traveling or whatever, five hours of sleep or six hours of sleep as opposed to my ideal seven and a half to eight, my glucose is just phase shift up a few points, and I noticed my spikes are larger.
Carbs are not the answer
Most Americans eat a majority of refined carbs and sugars. Unfortunately, that’s the opposite of what our bodies need.
The average American is eating refined carbohydrates and sugar so much throughout the day. Breakfast, we’re eating the cereal, and then bread for lunch, and then chips for a snack, and then potatoes at dinner. It’s carbohydrates all day. Insulin is always high, which means you’re rarely ever going to get into fat burning. That’s the beauty of a fat. You’re intentionally keeping that glucose, exogenous glucose low and insulin low, and being able to flip into metabolic flexibility to burn some fat. What’s cool about tracking this with the CGM is that you can see your glucose going low, which is a hunch. We can’t check insulin right now at home, but it’s a hunch that your insulin is probably low. Then you’re checking your ketones, and you’re starting to see the increased fat burning and fat oxidation happening, which are ketones as you get into the fast.
Keep in tune with your body
If you are already stressed or low on sleep, try to limit additional stressors on the body, such as a new diet.
The body can adapt, but we don’t want to do it so much that we’re actually causing dysfunction in the body. If you’re not getting a lot of sleep, and you’re exercising a ton and there’s a lot of life stressors going on with work and family or whatever, that might not be the time to do an extended fast, to just dump one more stressor on your body. For a woman, if you’re in a certain part of your cycle that’s particularly taxing on you, and you’re training for something athletically, and stuff is busy with school, that might not be the time to throw another stressor on your body. That is something worth thinking about. I tend to do fasting when things are pretty smooth and stable in my life, and I know my body can handle that extra bit of stress.
Seek a personalized health plan
A good doctor will work with you to get your body on the right track.
For everyone, it’s so personalized. The best thing to do is to work, I think, with a great physician who’s thinking in an integrative systems biology way, so whether that’s a regular MD who’s really, really thinking holistically and deeply about metabolic health or someone with a naturopathic physician or functional medicine or whatever it is, someone who’s really thinking deeply about these things. If you’re struggling, really struggling with metabolism, there are a lot of these doctors out there like yourself, like myself who are thinking about that whole picture. That sometimes is what’s helpful is a guide to breakthrough if we’re feeling stalled in our progress.
Get rid of refined sugars
If you only do one thing to improve metabolism, Dr. Means recommends cutting our refined sugars and processed grains.
There’s no one size fits all, but I will say one thing that can be a huge step forward is just getting rid of the refined sugars and getting rid of the ultra refined and ultra processed grains. Those two things as just basic starting points can, I think, have a really big impact on reducing that glycemic variability, those ups and downs swings throughout the day. Just starting to read the packages minimize the refined sugar. There’s about 60 names for sugar, so learn what they are. Google what are the names for sugar, and try and avoid those. Try and figure out swaps for the ultra refined grain foods, which is literally everything. It’s bread, tortillas, chips, pasta, et cetera. Now, there’s alternatives for everything.
Set yourself up for a good night of sleep
Eating a healthy last meal earlier in the evening may just be the ticket to great sleep.
There’s a lot of really interesting stuff that goes on at night with glucose. I think a couple things to note is one, if glucose is all over the place in the beginning of the night, up and down, up and down, up and down, it’s definitely worth looking at your last meal of the day. Did that cause a big spike that then is leading to you spiking and crashing and then bouncing around? Sometimes high carbohydrate meals later in the evening or eating dessert or a drink with sugar in it or something after that dinner can lead to this jumping around overnight, which is not going to be great for sleep quality. I tend to move towards more keto-esque meals as the day goes on, because I don’t want to have those carbohydrates late in the night that are going to send me bouncing around.
Dr. Jade Teta: Welcome to the Next Level Human Podcast. As a human, you have a job to do. In fact, you have four jobs, to earn and manage money, to attain and maintain health and fitness, to build and sustain personal relationships, to find meaning and make a difference. None of these jobs are taught in school, and that is what this podcast is designed to do, to educate us all on living our most fulfilled lives through the mastery of these four jobs.
Dr. Jade Teta: I’m your host, Dr. Jade Teta. I believe we are here living this life for three reasons and three reasons only, to learn, to teach, and to love. In this podcast, I will be learning, teaching and loving right along with you. I’m grateful to have your company. Here’s to our next level.
Dr. Jade Teta: All right, welcome to the show, everybody. I am very excited today because I have probably the darling of the biohacking community right now on the show, Dr. Casey Means, MD, who is the chief medical officer and co-founder of the metabolic health company Levels. She also is the associate editor of the International Journal of Disease Reversal and Prevention. She has held research positions at the NIH, Stanford School of Medicine and NYU, and blah, blah, blah.
Dr. Jade Teta: She’s absolutely an amazing doctor and doing amazing things in our community right now. I’m incredibly honored to have you, Dr. Casey Means. Thank you so much for being on the Next Level Human podcast.
Dr. Casey Means: Thank you so much for having me. I’m just thrilled to have this conversation.
Dr. Jade Teta: I am too. I mean, it’s really interesting what you have done for our community. Now, of course, continuous glucose monitoring, CGM, has been around a little bit, but for those who don’t know, Dr. Casey Means has been one of the people who’s bringing this to the public in a very big way. And so if you haven’t heard of Levels Health, and you haven’t heard of Dr. Casey Means, you’re going to be hearing a lot about Levels and a lot about her in the future.
Dr. Jade Teta: I’m sure those of you who are in the biohacking community, and you doctors and physicians who listen to this show, if you do not know her, and you do not know about Levels, you’re going to want to make sure you check her out. Let’s just get into this really quick. Dr. Means, tell me and for us what is so exciting about continuous glucose monitoring? What is it? How did you get into it? I just want you to start wherever you want to start with this story.
Dr. Casey Means: Well, I love the way that you asked that question. What is so exciting about this? I really do think it is potentially exciting for everyone. The reason for that is because nutrition has been a black box forever. We put stuff in, and we don’t get really any feedback on it. We’re trying to… We eat a metric ton of food per year. We’re eating pounds of food per day, and we’re doing it flying blind. Continuous glucose monitoring can really help cut through some of that mystery.
Dr. Casey Means: This is a wearable device that you put on your arm, and 24 hours a day, seven days a week, it’s giving you biofeedback. It’s like a tiny little lab test on your arm continuously. That’s telling you how you’re responding to food with this really important biologic readout, which is glucose. Glucose is the fundamental unit of metabolism, and this is the fundamental substrate of metabolism in the body, which means it’s fundamental to how we make energy in the body, how we convert energy to food.
Dr. Casey Means: It changes constantly based on what we’re eating, how we’re living, things like stress management, exercise, sleep, how our microbiome is doing, how our micronutrient status is doing. It’s this readout of these complex variables around how we’re eating and how we’re living, and can give us tons of information about how we should personalize and shape our day-to-day diets and life. That’s really exciting, because the average American goes on a diet each year.
Dr. Casey Means: Over 50% of Americans are trying to go on a diet to lose weight each year. What does that say to us? That people are trying, people want to do better with food. People want to optimize their diet and lifestyle for better outcomes, and so to actually now have a tool that can give us objective, real information and not just hearsay, not just maybe the number on the scale the next day, not a cholesterol test six months from now, but immediate.
Dr. Casey Means: “I eat this,” and 15 minutes later, I have some feedback about whether that was really serving my goals or whether it might not be the best choice for me. I think that’s going to give people a lot of empowerment, and just a handhold in what otherwise has been notoriously a very open loop system with very long feedback cycles that are sometimes really unhelpful when you’re trying to determine individual day-to-day choices.
Dr. Jade Teta: I love the way you explain that. It really is flying with a blindfold up until this point. One of the things I’ve always talked about in my clinical practice is this idea of this silly little acronym I use called SHMEC stands… It’s S-H-M-E-C, sleep, hunger, mood, energy, ,cravings. What I used to say is there are two things required for fat loss in the body. We need a calorie deficit. and we need our hunger hormones balanced, so we can sustain that calorie deficit, so we need to keep SHMEC in check.
Dr. Jade Teta: The problem though is that SHMEC is a purely subjective evaluation. Now, along with this biofeedback we now have with this CGM device, this wearable device, an objective evaluation to go along with this that tells us exactly how food is impacting us. What’s exciting for all you listeners is one of the things I’ve oftentimes talk about and I’m known for is this idea that I wish for such a long time that we would do individualized nutrition rather than this cookbook cookie cutter, one size fits all nutrition.
Dr. Jade Teta: This to me allows us to do that. My next question to you, Dr. Means, is have you seen… Do we have research? Do we have data that you’ve been looking at that when a human… I eat the same food. Let’s say you and I both sit down, and we decide we’re going to have breakfast together, and you have a bagel and I have a bagel. How does this differ? Is there going to be differences between me and you in terms of how we metabolize that particular bagel? Will we see that on this monitor, and can we use that data to then change our nutrition choices?
Dr. Casey Means: Absolutely. That’s such a great example of a bagel because this is a standardized piece of food, and your bagel and my bagel are going to have the exact same amount of carbohydrates, and therefore the exact same amount of potential glucose that’s going into the body. What research has shown us over the past five years or so is that contrary to the glycemic index type philosophy, which is that when you eat a certain food like a bagel or a piece of white bread, it will cause a certain amount of glucose rise in the body.
Dr. Casey Means: What we’ve learned from the research is that that’s actually not the case. You and I very likely could have a totally different glucose response or glycemic response to that bagel. That’s because the bagel is interacting with this complex organism of different amounts of muscle, different level of insulin sensitivity, different microbiome, different micronutrient status, different sleep and exercise the day before or the day of the bagel. All of these things can factor in to that process of converting that bagel in the mouth to glucose in the blood being different.
Dr. Casey Means: That has really large implications for our health, because if I get a gigantic glucose spike, if my body and my physiology converts that bagel into a quick release of glucose in my blood stream, that’s going to have a different physiologic cascade to you if the bagel causes a very, very little glucose rise in your blood. When we get these large glucose excursions, these big, quick peaks after meals, that’s not great for our body over time.
Dr. Casey Means: Sure, in a healthy person who is not someone dealing with type one or type two diabetes, a big glucose spike after a meal, you can release insulin, and get that glucose back down to normal and process that glucose. Sure, that’s fine. But when those big spikes are happening maybe multiple times a day, day after day, week after week, month after month, year after year for decades, that has significant ramifications on our bodies and our physiologists. You don’t want to do that.
Dr. Casey Means: You want to stick with foods that have much smaller and more gentle glucose elevations to keep things sensitive and on track. That leads into a broader discussion about insulin sensitivity, which I’m sure your listeners are familiar with that concept, but basically, those big spikes, simply put those big spikes day after day are going to cause this insulin release to help you get it out of your bloodstream and back into the cells. When that happens over and over and over again repeatedly because of foods we’re eating that are spiking our glucose, the body can become numb to that insulin signal.
Dr. Casey Means: It seem too much insulin around, and it’s saying, “This is taxing us too much, and we’re trying to force too much glucose out of the bloodstream into the cells.” The cells become resistant to it, and the body has to pump out more insulin to drive that same amount of glucose into the cell. Then you start going down this pathway of insulin resistance. Where insulin is rising, ultimately, glucose is rising, and that’s when you start getting some of the real problems with metabolic dysfunction and that path towards a metabolic disease like obesity, diabetes, et cetera.
Dr. Casey Means: It is of great importance to us to understand which foods are going to keep our glucose a little bit more low and stable so that we can keep these systems sharp, and not be taxing our body so frequently with these big insulin surges. It’s not just the downstream insulin effects that are problematic over time. It’s also just the impact of glucose in the bloodstream in its own right. High glucose in the bloodstream can cause inflammation. It can cause oxidative stress.
Dr. Casey Means: It can cause glycation, which is a process whereby sugar just sticks to things in the body and causes problems, so you want to keep the glucose into a… You want to keep glucose in a healthy, low, fairly stable range as much as you can throughout your lifetime to really achieve the best possible outcomes in terms of current metabolic performance, but also long term of wins of chronic disease, longevity, et cetera.
Dr. Jade Teta: I love the way you described that. What’s really interesting about this, the old thought, was just like, “Okay, well, if Dr. Means and I eat the same food, we’re going to have the same risk of insulin resistance, because we’re eating the same kind of food.” What this new technology is doing for us is saying, “Okay, well, there’s a certain amount and type of food that I can eat versus a certain amount of type of food that you can eat to have a healthy level.” We can see this in these spikes.
Dr. Jade Teta: Then the other thing that’s interesting here… I want to see where you want to take us with this, because this is a question about this idea that I have seen clinically, oftentimes, people who seem to eat perfectly, or perhaps don’t eat at all, or perhaps are experimenting with things like intermittent fasting and things like this. When you look at their blood sugar levels, you actually see that their blood sugar levels are running high, perhaps that you’re looking at them and saying, “Well, that’s interesting. They seem to be eating “healthy.” T.
Dr. Jade Teta: Hey seem to be doing “the right things” that the books say or that the latest guru says or the latest podcast says, or the latest documentary says. Yet, their blood sugars are high,” which brings us into this question of stress also, and you already alluded to this, can raise blood sugar. One of the things we oftentimes see clinically is someone who wakes up with high fasting blood sugar levels, despite eating a very “healthy diet.” I’m using that in quotes because I think this new CGM technology actually tells us now what maybe we thought was healthy may not always be healthy for us.
Dr. Jade Teta: There’s another side to this insulin resistance food equation. Now, we can look at, even with CGMs, this stress effect in insulin resistance as well. You see this show up as well when someone’s maybe over secreting cortisol, having sleep deprivation issues, and you see blood sugars that are higher than you would think based on what they’re eating. Is there anything that you can say about that in terms of, “Are we able to spot stress effects with the CGM as well? Can we actually see when we’re stressing out and raising blood sugar levels versus when we’re eating and raising blood sugar levels?”
Dr. Casey Means: You bring up such a great point about the impact of things other than food on glucose. This is really important because what I like to say that diet is necessary but not sufficient for optimal metabolic health or optical glucose control. You can’t have perfect metabolic health or glucose control if your diet is off the rails, and tons of refined carbohydrates and sugars, but that’s a loan that’s not going to just… That’s not the panacea. You also need to dial in these other factors about our health, our diet and our lifestyle that have a really strong impact on insulin sensitivity and glucose levels.
Dr. Casey Means: Those things are really sleep, how much sleep we’re getting, the quality of our sleep, stress, so how we’re responding to stress, how much chronic low grade stress that we’re under, the acute stressors in our lives, and then physical activity, for sure. That’s a gigantic one. Those are the three modifiable activities each day that we can really dial in to have optimal metabolic health. Stress is so interesting, and we do see it come up on continuous glucose monitoring to the extent that if… I’ve seen this in myself.
Dr. Casey Means: The first time I gave a talk in front of people when I had my continuous glucose monitor on, I was fasting, so I hadn’t eaten any carbohydrates or sugar. My glucose went up about 30 to 40 points during that talk in a little peak just like a food induced peak, and then came down. Why is that happening if we’re not consuming glucose? It’s actually an evolutionarily adaptive response gone awry. So when the body’s under a source of threat, or it thinks that it’s in trouble, the body sends out hormonal signals, particularly cortisol and catecholamine hormones like adrenaline and things like that.
Dr. Casey Means: It sends those signals out of the body. There’s a threat, and we need to mobilize to get away from this threat. It tells the liver, which stores a little bit of glucose in it, to dump that glucose into the bloodstream to feed the muscles, so you can run from whatever you need to run from, to feed your brain so you can think sharp, all these things to get you mobilized. Well, now, a lot of our stressors like giving a talk or responding to a stressful email or the honking on the road, these things don’t require us to activate our muscles and runaway.
Dr. Casey Means: They’re just psychological stressors. They don’t require that glucose dump, so now you’ve got this glucose dump into the bloodstream from stress, but you’re not actually activating your muscles to use it. There’s no sink for it, so it’s just sitting there, and that’s going to lead to then needing to produce that insulin to get that into the cells. You’re basically inducing this spike for no good reason. This is where thinking through things like stress management techniques and giving your body signals that you’re safe and that you are not under a time of stress.
Dr. Casey Means: You’re not needing to run from anything. You can actually positively impact that hormonal cascade to prevent your body from having such a strong metabolic response. For me, what’s been fascinating, and I think for many of our members, is that aside from being food biofeedback, which in its own right is a huge step forward in terms of wearables and what we’re able to get from personal bio data, but also being a stress management biofeedback tool. Because when I see my glucose go up like that, I know I could have really done better in terms of managing my stress.
Dr. Casey Means: I also noticed that on days when I’m just chronically a little bit extra stress, something’s going on with work or with personal life or whatever, my glucose often just phase shifts up. Maybe I’m normally running… My baseline is around the eighties, and then after a meal, it’d go up to 95 or 100. I might see that it’s just always up at 90 that day. It’s starting at 90 and going up to 120 after meals, and so it just feels like it phase shifts it up.
Dr. Casey Means: I don’t have any evidence to support that that is… It hasn’t been shown in the literature that chronic stress leads to a baseline elevated glucose like that, but I’ve noticed it in myself, and the same is true with sleep deprivation. If I get, for whatever reason, traveling or whatever, five hours of sleep or six hours of sleep as opposed to my ideal seven and a half to eight, my glucose is just phase shift up a few points, and I noticed my spikes are larger. Hormones are so complex, and stress and sleep deprivation both have a huge impact on that cascade of all these counterregulatory metabolic hormones.
Dr. Casey Means: Just touching on the sleep piece, one night of sleep deprivation can cause people to be acutely insulin resistant the next day. We know that their cells need more insulin to take up the same amount of glucose. We’re all chronically sleep deprived, getting a little bit less than we need on average. The compounding effects of that over time are massive. I think that exactly like you were saying, there are opportunities for continuous glucose monitoring to be more than just a nutrition biofeedback tool, but really a holistic lifestyle biofeedback tool.
Dr. Casey Means: That’s what the Level software does. That’s what we bring together in the app is help parse out which pieces of that equation are being affected by your choices and your day to day life, and then how to optimize those things.
Dr. Jade Teta: It’s one of the things, I think, I love about what you’ve done the most, because when I was using just the Libre app before being introduced to you, the data, it’s very difficult to parse out what’s happening. One of the things I love about what Levels has done is make that very easy. For those of you who get introduced to Levels, one of the things that you could do is, that I love, you can literally take a picture of what you ate right before or right after, and then have your glucose excursion curve to look at based on that.
Dr. Jade Teta: I love the way that is. In terms of the stress thing, I’ve seen the same thing. One of the things that I think is interesting about discussions with physicians is for those of you listening to this, we’re at this place now where we have this really interesting technology. We don’t have a lot of the research to catch up, so a lot of us… You can hear this. I love this. I can tell that the way that you approach this is very open-minded, right? Same with me. We’re just like, “Hey, there’s a lot that we know research wise. There’s a lot that we don’t know.”
Dr. Jade Teta: For those of you listening, this is something that you’ve learned in the Next Level Human podcast a lot. As we get more clear in the science, you’ll be able to hear more definitive, more nuanced answers from people like myself and Dr. Means in terms of what this means. But right now, we’re in this really interesting place where we’re in data collection mode and making some guesses. One of the things… I have seen the same thing that you’ve seen actually.
Dr. Jade Teta: I’ll ask you to speculate, because I don’t know that we have any research on this, but maybe there is some research I’m not aware of. One of the things I’ve noticed with myself and with many patients who do intermittent fasting is some of these individuals will do intermittent fasting, and you’ll see on the CGM that their blood sugar levels are improved, which would make sense is what we would guess would happen, right? You go without food.
Dr. Jade Teta: If we’re just looking at it from that end, and we go, “Well, if you’re not getting these glucose excursions, you don’t need as much insulin. Therefore, insulin resistance is being improved.” However, there’s a whole other type of patient who when they intermittent fast, they’re getting, I believe, this stress response that Dr. Means is alluding to, and we’re actually seeing their blood sugars potentially get worse. We’re also seeing hunger and cravings being triggered, right? We all know that…
Dr. Jade Teta: Ask yourself, everyone who’s listening right now. If you fast all day or you fast for 16 hours, are you more or less likely to just have a salad and a chicken breast, or are you craving pizza and burgers and chips and things like that? I have seen clinically that there is some indication that the blood sugar excursions and what happens through fasting, if you’re getting this stress response, that you perhaps might want to eat a little bit sooner. I want to see if you would agree with this, or how you would think about this, because the way I see this, if this is a stress response, is there a way to preempt that stress response by giving the body what it’s needing a little bit of glucose, right?
Dr. Jade Teta: Instead of saying, “Oh, I’m going to fast because I heard paleo Pauli tell me that,” it’s basically, we now have the ability to check this. Do you have anything to say about that? Can this tell us whether things like fasting would be good for people? Are there some people getting this stress response from fasting? Are there other people who are not getting the stress response? What’s your thoughts on that, and what have you seen clinically?
Dr. Casey Means: It’s a great question. This is one where I’d be so excited to see more research done in this, because it’s like, we just don’t know. I mean, there’s been some small studies with fasting showing reversal of diabetes. Jason Fung has done some great research on this, and many other groups, but really showing the clinical power of longer fasts, but we don’t really have that study that shows in a non-diabetic, otherwise fairly healthy person, someone maybe who’s in the high normal range, maybe has a little bit of extra weight, early insulin resistance does a reasonable intermittent fasting protocol, improve overall glycemic levels, improve weight, et cetera.
Dr. Casey Means: That’s what I’d like to see in a CGM study. It’d be fantastic, because I know that for me personally, having used continuous glucose monitoring for two years, I see the impact of intermittent fasting on my glucose levels. What’s really neat about having a CGM on when you’re fasting is that you have this biofeedback throughout the day showing you that what you’re doing is having an impact. I’ve done a lot of 18-hour, six-hour fast, 18-6, just day to day. I’ve also done three-day fast before, and it’s amazing.
Dr. Casey Means: You see your glucose in the first day up and down, up and down, a little bit of variability. Then after about four to six hours, it starts trailing down, and then it starts trailing down some more. By 24 hours, it’s just at a low and flat level. It’s not budging. It’s just a line for the next two days. It’s this… You know that if you eat, obviously, it’s going to up. It’s this really motivating tool during a fast to say one, there is enough glucose in my blood stream because my body is actually…
Dr. Casey Means: Even though I’m not eating glucose during this fast, my body is making glucose. The body has all these ways of making glucose from other things in the body. In the liver, it can make it from convert from fat and amino acids into glucose. That’s amazing, a process called gluconeogenesis. Your body needs to keep the glucose in a stable range. Going too low is obviously very… It could be dangerous, and so to see that during a long-term fast and be comforted like, “Yeah, I’m okay. My blood glucose is 75. It’s not going too low. We’re good,” even if you’re hungry and starting to go a little bit panicky knowing that you’re okay.
Dr. Casey Means: On the flip side, your glucose might go quite low, and then you might know like, “Okay, I don’t feel good, and my glucose is low. I actually probably need to end this fast a little bit earlier.” That’s at least good feedback. I think that it’s also… Another thing that I’ve been experimenting with a little bit is using a ketone monitor, so to look for product of fat oxidation with my continuous glucose monitor during a fast. It’s so funny. I’m at my desk right now, and I actually have all my…
Dr. Casey Means: I’ve got all my monitors. I’ve got two blood ketone monitors. I’ve got a breath ketone monitor. I’ve got another breath ketone monitor, Lumen. I’m trying all of these different things, and what I love… When glucose is low… This is the physiology that I’m trying to capture with these devices. When glucose is low, your insulin is likely going to be low, because you’re not stimulating the insulin to be secreted because you’re not eating carbohydrates during a fast. Glucose is low, can assume insulin is low.
Dr. Casey Means: Well, insulin, one of its functions is to block fat burning. When insulin is high, it blocks fat burning. Glucose and fat are the two main ways we can make energy in the body. When glucose is high and insulin is high, it tells the body, “Don’t burn fat. We’ve got plenty of glucose around.” When glucose is low and insulin is low, your body can start ramping up fat burning and moving through those fat stores for energy. That’s what we want.
Dr. Casey Means: That’s metabolic flexibility. That’s saying, “Okay, my body is becoming adapted to burn fat when there’s low glucose.” The average American is eating refined carbohydrates and sugar so much throughout the day. Breakfast, we’re eating the cereal, and then bread for lunch, and then chips for a snack, and then potatoes at dinner. It’s carbohydrates all day. Insulin is always high, which means you’re rarely ever going to get into fat burning. That’s the beauty of a fast.
Dr. Casey Means: You’re intentionally keeping that glucose, exogenous glucose low and insulin low, and being able to flip into metabolic flexibility to burn some fat. What’s cool about tracking this with the CGM is that you can see your glucose going low, which is a hunch. We can’t check insulin right now at home, but it’s a hunch that your insulin is probably low. Then you’re checking your ketones, and you’re starting to see the increased fat burning and fat oxidation happening, which are ketones as you get into the fast.
Dr. Casey Means: I’ll sometimes start my fast with a ketone level of 0.8, which is just starting ketone production. By the time I finished my 18 hours, it’s up at 1.5, 1.6. That’s incredibly motivating to me, because it said, “You actually did something here. You kept the glucose low, and the readout of fat burning increased.” That’s a fun feedback cycle that I enjoy seeing as an extra level of motivation that this is not all for not. You’re actually… You are getting into fat burning here.
Dr. Jade Teta: I want to jump in real quick and tell you about one of my favorite new products. To start out, I want to ask you a question. If you had to follow your friends around, who are not the healthiest in the world, and see what they are doing, what would be the number one thing you would probably tell them to do to start? For most people, that’s going to be drinking more water, right? This is something that we talk about all the time in health and fitness. It’s almost as if we think of it as an afterthought now, because obviously, water is so crucial.
Dr. Jade Teta: However, we often times get this wrong. For example, did you know that when it comes to hydration, just drinking water can make things worse? Most people don’t know this. Why? Partly because most people are over drinking water, and under consuming the electrolytes that help water do its job. What we don’t realize is that hydration is not just about water. It’s about electrolytes, the minerals in there, as well as getting that water into the cells. You do not want to be over consuming water if you’re not getting your electrolytes right.
Dr. Jade Teta: This opens up a whole new discussion because most people are not getting their electrolytes right. For example, did you know that low sodium, too low sodium is an issue just as much if not more so than high sodium? In other words, what we want if we’re going to get the right electrolytes is to get the right amount of sodium and potassium and magnesium in the Goldilocks zone. We don’t want too much. We don’t want too little. We want it just right.
Dr. Jade Teta: This opens up a whole other thing here too, because people who are exercising, doing sauna therapies, doing low-carb diets are disrupting and losing lots and lots of their electrolytes. For example, when insulin is not around in low carb diets, you will excrete lots of sodium. In other words, under that state, exercising, low carb diets, all these things, you actually need more sodium. And so if you’re somebody who has been just drinking water, not paying attention to electrolytes and also feeling fatigued, feeling like you’re underperforming, not sleeping right, getting cramps, twitches, headaches, any of these things, then you are probably dealing with an electrolyte issue.
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Dr. Jade Teta: For those of you who have experienced… I want to just point a clarification, and correct me if I’m wrong on this, Dr. Means. One of the things that happens if you’re one of these people who are noticing when you first start a fast that your blood sugars are jumping all over the place, realize that… Remember, Dr. Means was talking about the breakdown of glycogen. Well, that’s going to take about 24 to 48 hours before that goes away, and so you may actually see blood sugar spiking a little bit from these stress hormones.
Dr. Jade Teta: You need to give that time. So oftentimes in my clinical practice, I say, “Yes, you may see that if you’re this stressed type person in the beginning while your glycogen has some of this storage glucose there. But as that glycogen drains, you’ll begin seeing that curve come down.” At the same time, a lot of people will say, “Well, I’m a little bit worried about my blood sugars going too low.” Typically, this is why I also like to measure ketones, because as your blood sugars go low, we’re not so concerned about your blood sugars being super low so long as the ketones are coming up with it, not going up to huge amounts that would be near 10 in someone who’s diabetic, but in that one, two, three zone, and you oftentimes will see that.
Dr. Jade Teta: I love this idea. Just so people understand the mechanism. When you break down your fat, you’re getting glycerol. The glycerol backbone is used in gluconeogenesis as are the amino acids as well. You’re fixing this whole issue. You can watch this biochemistry in real time if you understand this. It’s an amazing way to look at, and I do think it is motivating for people who are thinking, “Oh, well, fasting doesn’t necessarily work for me.”
Dr. Jade Teta: Well, maybe for you, you have to wait a little bit, and it’s going to take a little bit longer. It is this, “Finally, we have a window into what we’re feeling to understand this biochemistry.” Am I getting the biochemistry right there? Do you have anything to correct me on there, and anything to add?
Dr. Casey Means: No, I think that’s exactly right. I think the stress piece is important because like you said, fasting can be a stressor. We’re taking away our fundamental thing that we’re striving for everyday, which is food for survival. You take that away. It can be a stress signal, but something… That can lead, like you said, to potentially some erratic glucose in the beginning, because we’ve got the cortisol. We’re doing that liver glycogen release, et cetera.
Dr. Casey Means: I think over time, it does typically stabilize. Depending on the person, the glucose might stabilize in a fast after four hours. Maybe it takes a day, but it’s a really good point to note. It’s also a bigger macro point about like, “This is a hormetic stressor in the body. You’re causing stress.” If you are in a place… This gets at when you should do a fast. Fasting is probably not what everyone should be doing every single day. We have a certain capacity for handling all sorts of stressors each day.
Dr. Casey Means: And when you go over that, when you exceed that limit of what your capacity is, you’re going to have… It’s going to cause problems for the body. That’s when you’re just going to start leaning into dysfunction. We want to stress the body enough that it’s like a good challenge, but not… that we then learn to adapt. The body can adapt, but we don’t want to do it so much that we’re actually causing dysfunction in the body. If you’re not getting a lot of sleep, and you’re exercising a ton and there’s a lot of life stressors going on with work and family or whatever, that might not be the time to do an extended fast, to just dump one more stressor on your body.
Dr. Casey Means: For a woman, if you’re in a certain part of your cycle that’s particularly taxing on you, and you’re training for something athletically, and stuff is busy with school, that might not be the time to throw another stressor on your body. That is something worth thinking about. I tend to do fasting when things are pretty smooth and stable in my life, and I know my body can handle that extra bit of stress. Another thing to note is that I think fasting becomes less stressful over time, because your body does adapt.
Dr. Casey Means: If you’re doing your first 24-hour fast, and you’ve been eating carbohydrates for most meals, you’re a glucose dominant processor. You have not given your body a lot of time to burn fat. Those pathways of fat burning and fat oxidation might be a little rusty, or if you’re starting in a place where you’re a little bit insulin resistant, and your insulin levels are always a little bit higher, and so you just have really been putting the break on fat burning. Let’s say you launch into a 24-hour fast.
Dr. Casey Means: Your body’s going to be like, “What the heck? I can’t… I’m not making fat efficiently,” so you start running out of your stored glucose, your glycogen, and you are working through some of your circulating glucose, but your body’s not quite ready to ramp up into fat burning because you just haven’t done it that much. You’re going to feel like crap. You’re going to be hungry and moody, and it’s going to be stressful.
Dr. Casey Means: Now, let’s say you ease into it. First, you start by just eating a little bit of a lower glycemic diet. You learn how to keep your glucose more flat and stable with food throughout the day. Let’s say you do that for a month or two, maybe bringing your insulin levels down over time. Then you start doing a 12-hour fast. You stop eating after dinner, and then you eat… Let’s say you stop eating at 8:00 PM, and you start eating at 8:00 AM. That might be more than you’ve ever gone before, because maybe in the past, you’ve been snacking at midnight, and then eating at 7:00 AM, and just a seven-hour fast overnight.
Dr. Casey Means: Start easing into something, give the body a little bit more practice with burning through glycogen, moving into fat burning. Then ease into the 16-hour fast. Then maybe only after weeks or months, are you ready to do this longer fast? That’s not the case… This is not the case for everyone. I’m just saying that there are adaptations that the body has to make over time to use these pathways in the body, these cellular signaling pathways, these fat oxidation pathways. It can sometimes really be stressful when you just are right at the beginning and jumping in, so ease into it and think about the body as adapting over time.
Dr. Casey Means: I do think that fasting can become a little bit less stressful. I know for me, this is one thing I’ve learned about me with fasting is that it is much more stressful for me if I fast in the evening for a longer period of time versus the morning. I stay up late. That’s what I do. I usually go to bed around midnight. If I stop eating at six, and I have six hours before I go to sleep where I’m not eating, that feels like a big stress signal on my body.
Dr. Casey Means: However, if I stop eating at 8:30 or 9:00, and then fast in the morning for longer till maybe 1:00 or 2:00 PM, same duration of fast, but I’ve just shifted it towards more in the morning versus at night, much easier for my body. Doesn’t feel stressful, don’t get hungry. I avoided that for a long time, because there is evidence to suggest that it’s better for the body to stop eating earlier in the evening. Eating late at night can interfere with sleep. We’re a little bit more insulin resistant naturally at night, so eating late at night may have a little bit more of a heavy impact on glucose levels than if you eat earlier in the day.
Dr. Casey Means: I always thought it’s better to fast in the evening more than in the morning, but it doesn’t work for me. It’s stressful. I have noticed with checking my ketones and all this stuff, I still get the same benefit of ketone production and all this stuff if I fast more in the morning. It’s really personalized and individual, and that was a big breakthrough for me to learn that I’m going to be a morning faster, not an evening faster, and I’ve been able to be much more successful.
Dr. Casey Means: It’s really just listening to your body, and figuring out what works for you.
Dr. Jade Teta: I love your brain and your clinical approach. I often tell people there’s only one rule in nutrition, and that is do what works for you, and something like Levels helps you figure out what works for you. Actually, same thing for me. I’m aware of the research showing maybe it’s better to cut off dinner early and fast through the night. I simply can’t do that, but I don’t have much of an appetite in the morning, so I can go longer.
Dr. Jade Teta: Now, I don’t want the people who are not as savvy to think that we’re saying everyone should fast. It’s just part of the discussion is in fact… I’ll just give my clinical approach, and you can comment on it if you want, but I think we’re in alignment here. Typically, my approach for people who I’m trying to make more metabolically flexible is I pretty much start with a 12-hour fast and then small frequent meals within that 12 hours. Now, that is a very old concept that people go, “Oh, well, why are you doing small frequent meals?”
Dr. Jade Teta: Well, for someone who is not able to manage their blood sugar, first of all, I want them to see how food’s impacting their blood sugar. I also want them to avoid hunger and cravings. Then slowly but surely, I began to say, “Okay, what do you think about perhaps now cutting out the snacks, and just going breakfast, lunch, and dinner?” Then, “Oh, what do you think about perhaps having a smaller breakfast or a smaller dinner?” It’s a step-wise process, and it sounds like you’re using something similar here versus someone who’s very athletic, more metabolically flexible.
Dr. Jade Teta: Perhaps they can launch right into a fast, but for most people who are the average American, we’re eating big, huge meals filled with junk food. I’m typically like, “Let’s just get you equal time during the day eating and not eating, and let’s control hunger and cravings by having small frequent meals, and then slowly taking those away as we see that glucose curve began to figure itself out.” What you oftentimes see is the peaks get less high. You’ll see more peaks and less plateaus in the glucose curves.
Dr. Jade Teta: This to me means improving their insulin resistance, and being able to make their metabolism more flexible. I love the way you say that, because in a sense, we do have different pathways. I mean, everything is running down to Acetyl-CoA in a sense, but if you’re not running that fat burning pathway, it does build up cobwebs so to speak. You have this issue that if you’re only eating glucose all of the time, you’re running that pathway pretty nicely, but you’re not burning fat, and so this begins the process.
Dr. Jade Teta: I don’t know if you have any comments on that, but the next couple of things before we wrap up is I do want to know a little bit about how this is working. Let’s talk about some edge cases, but anything that you finally have to say about the process by which you would begin managing blood sugar for somebody who’s never done this before versus the biohacking community who’s very much into this.
Dr. Casey Means: I mean, for everyone, it’s so personalized. The best thing to do is to work, I think, with a great physician who’s thinking in an integrative systems biology way, so whether that’s a regular MD who’s really, really thinking holistically and deeply about metabolic health or someone with a naturopathic physician or functional medicine or whatever it is, someone who’s really thinking deeply about these things. If you’re struggling, really struggling with metabolism, there are a lot of these doctors out there like yourself, like myself who are thinking about that whole picture.
Dr. Casey Means: That sometimes is what’s helpful is a guide to break through if we’re feeling stalled in our progress. I think for the person who’s the person who’s just getting started and is really just trying to dip their toe in, I think everything you said is totally right. Really start incrementally. Maybe even that 12-hour fast is really hard in the beginning. I know that for me, sometimes 12 hours can feel like a really, really long time. Like you said, just starting by getting those glucose elevations down.
Dr. Casey Means: Trying to just start by avoiding the big spikes, that can do wonders for the body. Like you said, there are no rules for nutrition. There’s no one size fits all, but I will say one thing that can be a huge step forward is just getting rid of the refined sugars and getting rid of the ultra refined and ultra processed grains. Those two things as just basic starting points can, I think, have a really big impact on reducing that glycemic variability, those ups and downs swings throughout the day.
Dr. Casey Means: Just starting to read the packages minimize the refined sugar. There’s about 60 names for sugar, so learn what they are. Google what are the names for sugar, and try and avoid those. Try and figure out swaps for the ultra refined grain foods, which is literally everything. It’s bread, tortillas, chips, pasta, et cetera. Now, there’s alternatives for everything. There’s black bean pasta. There’s zucchini noodles for pasta. For bread, we’ve got coconut flour bread, which is much lower carb. You can use butter lettuce for your taco shells.
Dr. Casey Means: You can use chard or collard greens for your burrito wraps. There are so many things that you can do to eat the same foods that you love that are not having all these refined carbohydrates. We have tons and tons of information about swaps like that on the Levels blog, because I do think… I know for me, you don’t want to feel like you’re just depriving yourself of everything you love, but easy, simple swaps can sometimes do wonders in getting that glucose spike down.
Dr. Casey Means: For me, mashed potatoes or any type of potato product sends my glucose up like 80 points, which I never want to do. I never want my glucose to spike 80 points after a meal. But when I switched to cauliflower mashed potatoes, which I can now make to taste exactly like regular potatoes, I have zero spike. That’s it. I’m eating the same thing. It looks the same. It tastes the same, and it’s an 80-point glucose difference. If you can start to do that for lots of different things that are causing you spikes, you’re going to be well on your way moving towards a more optimal metabolic health and metabolic flexibility.
Dr. Casey Means: That’s all I’d say on that, but I think your approach is spot on.
Dr. Jade Teta: That’s a great discussion. Why don’t we talk just a little bit about helping people manage this? What would you say we should be looking at in terms of our glucose spikes? How high should these things be going? Is there a number we should be trying to keep it below? What would be optimal there when we’re looking at this on a CGM?
Dr. Casey Means: First, I’ll just say what is the standard guidelines. Right now, all we have to go off of is really the American Diabetes Association ranges for what’s normal, what’s pre-diabetic, what’s diabetic. In the International Diabetes Federation, IDF, their guidelines, what they say is if your fasting glucose, so your morning glucose right when you wake up, is under 100 milligrams per deciliter, you’re considered normal. If it’s between 100 and 125, you’re considered pre-diabetic. And if you’re 126 or above, you’re considered to have type two diabetes.
Dr. Casey Means: Then we look at post-meal levels. After you eat, where does your glucose go to? Based on the… There’s actually not a guideline for this for non-diabetic individuals. All we know is that this is what’s called an oral glucose tolerance test, which is where you drink a 75-gram glucose strength, and then if your glucose is under 140 milligrams per deciliter after two hours, after that drink, based on American Diabetes Association criteria, that’s considered to be non-diabetic. That’s not very helpful.
Dr. Casey Means: It doesn’t tell us like, “Okay, well, what should we shoot for after a meal for optimal health?” The International Diabetes Federation does have a take on this, which is that your glucose should never go above 140 milligrams per deciliter after a standard meal. You should stay below that at all times. That’s great. That’s all helpful for clinical stuff, but what about what’s optimal? What do we want to shoot for? That’s where I’m getting into more personal opinion and my interpretation of the literature.
Dr. Casey Means: Let’s talk about fasting glucose first. That’s first morning glucose when you haven’t eaten or drank any calories for eight hours. If you look at the research… First of all, lower is not always better. We want to stay within a healthy range. We need glucose in our bloodstream. Let’s say 70 is about the lower limit of where we want to be for our blood glucose, and above 100 is considered pre-diabetic for fasting glucose, so we’re in that 70 to 100 range. Based on standard clinical criteria, we’d say, “Oh, well, everything between 70, 100 is probably the same, because it’s all normal.”
Dr. Casey Means: Not true. If you look at the research, as fasting glucose increases over time from the 70s up to 100, we increase our rates of stroke, of heart disease, of diabetes, of obesity. You want to stay in that low normal range of fasting glucose, not that high range. If your glucose is 99 milligrams per deciliter fasting, very different than someone who’s fasting glucose is 75 milligrams per deciliter. I usually say between 72 and 85 milligrams per deciliter is an optimal fasting glucose based on what I’ve looked at in the literature.
Dr. Casey Means: Then looking at post-meal spikes, this one’s even harder. We have really no guidelines on this. If you look at studies of large non-diabetic populations wearing continuous glucose monitors, just free living, what we find is that actually, most people spend the vast majority of their time between 70 and 120. I would say for people listening, if you’re keeping your glucose below about 120 after meals, ideally, I try and be below 110. I think that’s starting to get into a better range.
Dr. Casey Means: So putting that all together, probably sticking between 70 and 120 for the vast majority of your day is good. I tend to try and stay between 70 and 110, 70 and 100, just keep it pretty tight. That works well for me. How about you? I’m curious what your ranges are.
Dr. Jade Teta: Well, personally for me, people who listen to the podcast know I tend to run in pre-diabetic ranges, so it’s interesting that I do this work, and I struggle pretty mightily to control my blood sugars. I’m this stress reactive type, so my blood sugars will go up pretty high, but I would agree with you. In my clinical experience with other individuals, I usually look at 120, 140. I’m like, “If you’re starting to get up in that 140 range, I’m a little bit worried about you. If it’s peaking up there after meals, I prefer it to be under 120.”
Dr. Jade Teta: Honestly, ideally, the less the spike, the better as far as I’m concerned, right? What we really want is the body to be able to clear that glucose really quickly. I think I’m right on board with you there. This brings up other things too that you’ll see. Certainly when I am working out, my blood sugars will go up really high really fast. I oftentimes see if I’m sleep deprived and things like that. They’ll go up more. I also noticed that. I’m wanting that to be relatively similar to meals, although I will oftentimes see in the workouts that I do, CrossFit, I’ll see it go up much higher than my meals.
Dr. Jade Teta: I’ve seen that in athletic populations that these blood sugars can spike pretty high, which makes me just like, “I wonder what that’s about, and we’ll figure out what that’s about.” I don’t know if you’ve seen that either. So partly when you get the stress effect, when you’re out there running away from the lion, let’s say working out, you’ll see these things spike a little bit more. That’s something that I don’t think we have much research on it all. I haven’t really seen any, but I’ve certainly seen clinically that that’s happening.
Dr. Jade Teta: Because these people are so fit and so healthy and so productive, and they clear that glucose pretty quickly, I’m not concerned about that. One of the things I also will say about working out is a nice walk after one of those workouts clears that glucose even faster, and one of the things that I’ve seen clinically that is really, really useful for people who are having high blood sugar. We have to remember the muscle is an independent glucose sink, independent of insulin when it moves.
Dr. Casey Means: Insulin, yeah.
Dr. Jade Teta: It actually puts those glute receptors out there in the same way insulin does, and so movement is a big piece of this as well, but I would agree with you. I would say we want to limit those glucose excursions as much as possible, and certainly, 120 and 140 are the numbers that I’m looking at. 140, I start to get worried. 120, I’m thinking that’s optimal. Really, the people who are really healthy and eating very healthy diets and low-carb diets, they’re not getting… They’re sometimes staying right below 110 and 100 sometimes.
Dr. Jade Teta: By the way, from my perspective for those of you listening, I think that really is. I’m right there with you, Dr. Means. I really think that’s where we should be getting to, and it does take time. There are some edge cases like myself and other people that I’ve worked with that are difficult to figure out what’s going on. I suspect mine is sleep apnea, so I’d get these… I have sleep apnea. I snore, and I’ll often time see my blood sugar spike in the middle of the night. Actually, that’s a question I have for you clinically.
Dr. Jade Teta: One of the things you’ll oftentimes see on the CGMs is glucose spiking in the middle of the night, and people are oftentimes concerned about that. Do you have any indication of what’s going on there with individuals? I see it happen a lot with people who have apnea. Obviously, if you’re not getting oxygen, this is going to create a stress response, and you’re going to get this adrenaline surge. It may even wake you up, but you’ll see glucose rise.
Dr. Jade Teta: Those are all my thoughts on that, but I mean, I’m wondering. I’ve seen it quite a bit with looking at CGMs, and it’s really neat, right? It’s the first time we’ve ever been able to see what’s happening with us in the middle of the night. Any thoughts about that that you have would be useful for us.
Dr. Casey Means: There’s a lot of really interesting stuff that goes on at night with glucose. I think a couple things to note is one, if glucose is all over the place in the beginning of the night, up and down, up and down, up and down, it’s definitely worth looking at your last meal of the day. Did that cause a big spike that then is leading to you spiking and crashing and then bouncing around? Sometimes high carbohydrate meals later in the evening or eating dessert or a drink with sugar in it or something after that dinner can lead to this jumping around overnight, which is not going to be great for sleep quality.
Dr. Casey Means: I tend to move towards more keto-esque meals as the day goes on, because I don’t want to have those carbohydrates late in the night that are going to send me bouncing around. That’s one thing with sleep and food. Another is that our sleep cycle actually has an impact on our glucose levels. In REM sleep, our glucose tends to drop a little bit, so that can make it look like it’s going down and then up again. There’s also just a phenomenon called pressure-induced sensor error, which is where if you lay on your sensor…
Dr. Casey Means: I’ve got my sensor on the back of my arm here. If you lay on it, it can cause a sharp drop, and then it’ll look like it’s springing back. Those are some things to keep in mind about nighttime readings. Then sleep apnea, I think that certainly could be an important component of why people might be spiking at night. If you are having an apneic episode where you stop breathing or occluding your airway, and then you’re gasping for breath, that’s going to lead to your heart rate going up. It’s going to lead to that stress response.
Dr. Casey Means: Definitely a plug for anyone listening, if you’re a snorer, or if you’ve ever been told that you had that gasping at night, definitely get checked out for sleep apnea. It is just something that’s, in many cases, easily treatable, and something that will really have wide ranging of positive effects on health. As a former ear, nose and throat surgeon, I pretty care a lot about sleep apnea, because getting interrupted sleep is just… It’s going to have far reaching effects on health, and on the flip side, a quality night’s sleep can just be an amazing medicine for so many different things.
Dr. Jade Teta: One other thing we didn’t mention actually is alcohol. For those of you who drink at night, this will suppress glycogenolysis, so the break down of glycogen, and so you may see the brakes come off this in the middle of the night too. Alcohol could be playing a role here as well. I want to be respectful of your time, but let’s talk about a couple edge cases here that maybe you have some insight on and maybe you don’t. But one of the things that I oftentimes see in…
Dr. Jade Teta: I work with a lot of athletes and a lot of biohackers. A lot of them are doing cold plunges and sauna therapies and stuff like that. You will see large blood sugar excursions with sauna therapy in particular similar to what you will see with workouts. Obviously, this is a thermal stress. It’s, again, a hormetic response. We use these things, but have you seen this as well, and should we be concerned about that kind of thing, sauna therapies, cold plunges? Are they going to have an impact on this, and are you concerned about it, and have you seen it clinically?
Dr. Casey Means: I’ve definitely seen a lot of spikes with people going into a cold plunge bath or with a really hot shower. I think there’s two pieces going on in here. I think one is the body’s stress response, like you said, causing that same thing that we see with high intensity interval training exercise, with stressful psychological events with this cold as a stressor. You might see glucose that go up just because of that.
Dr. Casey Means: There are also maybe impacts on the sensor as well and just how it’s reading, so something that I really like to do is to check a finger prick glucose when it’s in a acute shift like that to just verify like, “Is this actually happening in my blood, or is this something that’s going on with the sensor?” When I’ve done that or had other members at Levels do that, it varies the extent to which it’s actually capturing a real spike versus maybe artifact from the sensor and the temperature.
Dr. Jade Teta: I do the same actually. I definitely do the same. Actually, another edge case is… This will be funny. You’re probably like, “Jade, you’re crazy.” I have some friends who will put sensors on both arms, and try to correlate.
Dr. Casey Means: Yes.
Dr. Jade Teta: You’ll see a pretty big difference sometimes between those. I wonder if you have any thoughts on that because they just go, “Is this thing even accurate? I’m getting a 20-point difference from my right arm to my left arm.” Is there any tips you can give us there why might that be happening?
Dr. Casey Means: Yeah. Every lab test, every wearable is going to have some degree of inaccuracy. That is just the reality of any test and any wearable, and continuous glucose monitoring is about 9% in terms of variation between what’s in the blood and what’s on the CGM, what’s the CGM is reading, continuous glucose monitor. That’s-
Dr. Jade Teta: Because it’s not really measuring blood, right? It’s measuring the interstitial space, which correlates, right? Am I correct in that?
Dr. Casey Means: That’s right. Glucose basically seeps out of the blood vessels into the space around the blood vessels, the space around the cells, which is called the interstitial fluid, interstitial space. That’s where the glucose monitor is actually picking up. There can be about a five to 15-minute delay between what’s in the blood and what’s in the interstitial space, but they tend to be very closely correlated, but with about… Based on the studies that the manufacturers have done of these CGMs, so Dexcom and Abbott, it’s around a 9% to 10% difference.
Dr. Casey Means: That’s pretty standard across most wearables. It’s not like it’s compared to your Apple watch or WHOOP or whatever measuring your heart rate. That’s pretty typical. These are devices that are being used for diabetes management as well as for wellness purposes like what Levels is using this for. These are FDA-approved to be considered accurate enough to treat clinical conditions. The question of these differences, maybe someone wearing it has a 20-point difference between the two arms. Certainly have seen that.
Dr. Casey Means: One thing that I think is important to remember is that the delta between before a meal and after a meal, that’s what I care most about. I do care about baseline levels as well, but I’m really care most about the dynamic changes. That’s something that’s usually going to be pretty standard between your different sensors, but you may notice a little bit of a different baseline between the different sensors that you wear. For people listening, you wear these sensors for 10 days to two weeks, depending on the brand, and so this sensor, I’m going to have on my arm for two weeks, and then I’ll take it off and put a new one on.
Dr. Casey Means: It’s possible the next one I put on, my baseline looks a little bit different, four or five or 10 points different. The nice thing about the brand, the Dexcom CGM, which is one of the manufacturers is you can actually calibrate. I can do a finger prick of my glucose. Let’s say it’s 10 points different from my sensor. I can put that into my phone, what my actual blood glucose is, and it will actually calibrate. But the big picture point is that those deltas between before and after meals and the overall 24 hour trends, that’s what I care about more than just the concrete value of like, “Am I 90, or am I a 93 at baseline?”
Dr. Jade Teta: That’s such an important point. By the way, those who are listening, it’s the same thing when you’re looking at bioelectrical impedance machines for fat loss and stuff like that. Those things aren’t… It’s not the accuracy of the actual measure. It’s just the change between the two. A final question from me, because I know a lot of people do IV therapies and things like that, so vitamin C, you can see some pretty huge peaks.
Dr. Jade Teta: What can you tell us a little bit about that? Why is that happening with people getting these huge blood sugar responses after going through vitamin C therapies and things like that, IV therapy?
Dr. Casey Means: I’m pretty sure the mechanism of this is that it’s causing a sensor error here.
Dr. Jade Teta: That’s my understanding too.
Dr. Casey Means: If you’re getting an IV vitamin C infusion or something like that, you may see a totally erroneous value there. I would say don’t take that one-
Dr. Jade Teta: Those two compounds look very similar, so a lot of people say, “Maybe it’s thinking it’s glucose,” but yes, I mean, I’ve seen people go up to 400, 500, and I’m just like… That’s just the vitamin C in it.
Dr. Casey Means: Oh wow. Wow.
Dr. Jade Teta: Well, one of the things I want to… I always want to say this is the Next Level Human podcast, and one of the things I know as an entrepreneur is that it is incredibly difficult. People don’t really know what it takes to do something like what you have done. It is a gift to the world. I don’t think people really understand the risk you take and all the things you do to bring something like this to market. We are indebted to you. I am so grateful for your work.
Dr. Jade Teta: It’s just so important, Dr. Means. I just think you’re just a wonderful human for doing this and bringing this to all of us, so thank you so much. Is there anything else you want to leave us with and make sure that we understand before I let you get back to your day?
Dr. Casey Means: Well, first of all, thank you so much. I’ve got an amazing team, five co-founders who I did this with. We’ve got a huge team of people. Definitely, it’s amazing starting a company and leaving surgery to do this, and so grateful for the group of amazing people I have around me helping get this off the ground. I think the thing that I would just conclude with is that the beautiful thing about the human body is it’s so adaptable, and the metabolic health, it is really the core foundation of our total health.
Dr. Casey Means: It’s the core pathway of how we make energy for every one of the 37 trillion cells in the body. Our modern life, our modern diet and lifestyles, industrialized, high stress, low sleep, low physical activity, it’s hijacking this core fundamental system of our body that makes energy. That lack of being able to efficiently produce energy in the body is causing the dysfunction that we’re seeing showing up as all the chronic diseases we’re dealing with today. We’ve got to get metabolic health on track for real true fundamental health.
Dr. Casey Means: But the beauty is that even if we’re down the spectrum of going off course with our metabolism or metabolic health, we can turn the tide. We can go in the other direction. The body is so adaptable. And when you give the body the right conditions, the right environment, and you create that environment through food, through how you’re responding to stress, through how you’re sleeping, through how you’re moving, through how you’re supporting your microbiome, through the micronutrients you’re putting in your body, through avoidance of toxins, that’s the environment you’re creating.
Dr. Casey Means: When you give it what it wants and what it thrives in, it will turn in the right direction. It will adapt and get back on track. It’s not a one-way street, so just a very… It’s helpful. We always have room to turn things around and go in the right direction. We can take really simple steps to do that. I’m really grateful for you and your podcast, giving people those tools and that information and synthesizing it so that people can do that, and really grateful to have had this chat. Thank you so much.
Dr. Jade Teta: Same with me. Dr. Casey Means, thanks so much for your brain. Thanks for your amazing work. We appreciate you so much. We will talk to you soon. Have a great day.
Dr. Casey Means: You too.