#173 - AMA #26: Continuous glucose monitors, zone 2 training, and a framework for interventions

Foreign. Hey everyone. Welcome to a Sneak Peek, Ask Me Anything or AMA episode of the Drive Podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to Peteratti md.com subscribe so without further delay, here's today's sneak peek of the Ask Me Anything episode. Welcome to Ask me anything episode 26. I'm once again joined by Bob Kaplan. In today's episode, we field a bunch of questions that are kind of follow up questions to topics we've recently done deep dives into. The two main themes are more follow up on CGM and more follow up on Zone 2. Now when Bob first told me that those were going to be two of the things we're going to talk about, my first thought was we have nothing else to say on these topics. We have spent so much time on them. But it turned out I was wrong. There were a lot of really good questions here and things I hadn't considered. So if you find yourself wanting on either of those topics, this episode is definitely for you. If you think you know everything on those, it's probably still for you. The time of the recording here was in the middle of the Tour de France, so we had a little digression on performance, physiology and cycling. Now remember, if you're a subscriber and you want to watch the full video of the podcast, you can find it on the Show Notes page. If you're not a subscriber, you can watch a sneak peek of this video on our YouTube page. So without further delay, I hope you'll enjoy AMA 26.

Hello Peter.

Hey, Bob. How are you man?

I'm doing well, how are you?

I'm great.

Okay, you ready for an ama?

I am. I saw the agenda. It's very aggressive.

Yep, that's how I like it.

Ambitious, yes.

Yeah, to say the least. I don't know if we'll get through everything, but we did get a lot of follow up questions on CGM based on our previous. Actually I think it was the previous AMA where we talked about glucose. We talked about mean glucose, glucose variability and glucose spikes. And then we also had that Sunday email on CGM and non diabetics that was related to a JAMA perspective talking about it. So there's a bunch of questions on that.

Okay.

We also have a couple of questions on aura, the sleep wearable, the aura ring. We've Got some exercise related questions and we may work in one or two additional questions if we have time. How does that sound?

I think it sounds like a good list.

Okay. So, Peter, since we have a lot of these CGM related questions, one of the things that I've heard you talk about is you have a framework for interventions that I think will be really helpful in laying the foundation for how you think about CGM and their use in different populations. So can you start off by telling us a little bit about that framework?

Yeah. So again, it doesn't pertain to CGM specifically. It pertains to anything that comes across my plate. And the first time I actually contemplated this was really when I started trying to look critically at the data around meditation. So this was probably about maybe eight to 10 years ago. But anyway, it basically asks a series of questions. So the first question is, what is the risk of harm from doing this thing? That's a direct question. So if you do X, how high is the probability of harm? The second question is obviously the contrapositive of that. If you do X, what is the probability of benefit? And then the third question, and by the way, before I go to the third question, those first two questions are so obvious that they're almost not worth stating. And of course that's mirrored in the way the FDA organizes drug trials. Right? So a drug trial is organized first by, well, after you get through the preclinical data, the animal work, after the IND has been filed. Your first trial in humans, which is called a phase one trial, is looking at harm. I mean, it's typically a small trial with dose escalation that is only trying to understand if, as you escalate the dose, do you see an increase in side effects? Very occasionally you see some benefits in a phase one trial. And if you do, that's interesting, but you generally can't take it to the bank because the study is so small and generally it's quite homogeneous. So that's when you move on to phase two studies which are geared towards efficacy. That is, is this thing doing good? And of course, if the phase two trial is positive, you move to a much larger trial trial called a phase three trial, which really doubles down on efficacy. Of course, both of these trials will continue to be able to pick up any signal of harm. So you're always in the spirit of trying to capture that. But the real point here is you're raising the bar, so to speak, for what you're demanding of this. So again, what's the risk of harm? What's the probability of benefit are two obvious questions. I think the third question then is what's the opportunity cost of this intervention? And I feel like I've talked about this on a previous podcast before, and maybe it was even one of ours, but there was this device, sort of a device that you would listen to and it would supposedly put you in a trance. And the company that was proposing this thing had all sorts of theoretical benefits from using it. If you listened to this device, you were less likely to get breast cancer and all of these other things. So was there any harm in this device? As far as I could tell, no. I really didn't think that listening to this device was harmful in any way. Was there any benefit of this device? Certainly not to the extent that they made claims. That said, I had tried the device because a friend of mine bought it for me, and I have to admit it was the most relaxing thing I'd ever done. In fact, virtually every time I tried it, I fell asleep. So maybe there was some good in that, maybe there was some bad in that if it was a daytime nap, and you could speak to the disadvantages of daytime napping, but there was an opportunity cost to it, and I don't just mean financial. So the device was pretty expensive. I want to say it was like 1000 bucks if you were going to buy the thing. Well, 1,000 bucks is no trivial sum of money for anyone. So that's obviously something that has to be weighed against what else could be done with an opportunity cost. But the other thing you have to keep in mind is their prescription for use was two 20 minute sessions a day, much along the lines of Transcendental meditation, which is similar but has much better data. And that's where I kind of thought, well, there's a problem because for most people who are super busy, 40 minutes a day for very questionable benefit didn't make a lot of sense if it came at the expense of other things that undoubtedly had benefit, such as could that be 40 minutes a day of actual meditation? Could that be 40 additional minutes a day of sleep? Could that be 40 minutes a day of exercise? All things that I would point to as having far greater evidence in favor of. So I think anytime you're thinking about doing something, you want to kind of go through that. And those are especially important questions to be asking when the answer is not readily apparent from RCTs that have generally already answered 1 and 2. Now, remember, many RCTs are the easiest RCTs to do, are the ones that are based on pharmacology and they're generally addressing one and two, but they're not really addressing three because there really isn't much of an opportunity cost to taking a pill outside of the economic cost. But the, the time cost of it is relatively low. Of course, when it comes to RCTs that are more intervention based, such as exercise, yes, you want to be able to think about this. But as you look to something like CGM in the case of non diabetics, this framework to me is very helpful because at this time we don't have great RCTs to point to that, say in people who are not yet diabetic. There is a benefit to using cgm. So again, as you go through that, you ask yourself the question, what is the risk of harm? And again, when we talk about CGM specifically, I think the risk of harm is very low. If we were going to speculate what could be harmful about it. Well, I think the most obvious thing that comes to my mind is anxiety that it can stoke, right? It can create obsession in someone. And certainly I can speak to that personally. I don't think personally I've found it harmful, but I could absolutely understand that. And I frankly think we have some patients in whom I've never recommended it. So for example, we have some patients who have a history of eating disorders. These are patients. I would not in any way shape or form advocate the use of cgm. I think it's yet another tool that can create a negative cycle around obsession. Is there any chance of it doing good? Well, I mean, I think I've already made the case for that. I think there's ample chance for it doing good on two fronts. Right? The first front is what I call insight based good, which is teaching you what your carbohydrate tolerance is. That's what the tool is for. And then secondly, what I would call behavioral good or behavior modification, which is effectively a strapped on version of the Hawthorne effect. So when you're wearing a cgm, you're basically utilizing a tool that is monitoring you. And there is no shortage of data to support the idea that when people are asked to monitor food intake, they make changes in the right direction. So if I said to you, Bob, I want you to record everything you eat for the next month and track it in a food diary, are you going to make better food choices than you are making now? And the answer is unequivocally, yes, you are going to do that.

Which is also not to pile on. I guess this is the first time I'm mentioning observational epidemiology so far, at least for this episode. But that's one of the challenges right there with food frequency questionnaires is that they start asking them to ask them what foods they're eating, or they ask them what foods they ate. And oftentimes just that by asking, they're changing their behavior. And so you're not really getting an accurate representation of what they ate previously.

Right. So that's a problem that plagues epidemiology, but you can use that to your advantage. Right. So, you know, and we do that stuff clinically. Right. This is how you create accountability for patients. You say, look, we're going to check in once a day and I just want you to tell me what you ate. And even if you provide no other instruction, which is, oh, I want you to have this many grams of protein and this many grams of carbs and this many grams of fat. No, no. Even if you don't go to that level, if you just say, I just want you to tell me what you ate, that level of accountability immediately changes a person's behavior. And that's an example of how you can use that to your benefit. I guess I'll get to the third point, which is opportunity cost. So what's the opportunity cost of one of these devices? Well, I think hands down, the biggest opportunity cost is the economic cost. These things are not cheap. And if you are not diabetic, you are not going to have your insurance company cover one of these devices. So there are no shortage of companies out there that are repurposing and repackaging CGM. So there are really three companies that make CGMs in the clinical grade. So there's Medtronic, Abbott, and Dexcom. And again, by way of full disclosure, I consult with Dexcom, not on their CGM business, but actually on a part of their business that deals with other analytes. So other things that you could measure. So actually, they don't really interact much on the CGM side, but those three companies make CGMs. And then there are lots of companies like Levels and Super Sapiens that people have heard of who are plugging in those CGMs into their apps to help users with their goals, be it weight loss or otherwise. Well, they're not cheap. I'm trying to remember what the cost is, the monthly. I mean, I feel like the daily cost of CGM is about 10 bucks and there's probably cheaper ways to get it. If you're buying your CGM on eBay or if it's a little bit expired. But directionally speaking, it's about a $10 a day habit. That adds up, right? Call it $3,500 a year. That's a huge expense, assuming you need it every minute of every day. And I don't think you do. I think you can gain a lot of insight using these things periodically. I don't think this is something you need to be tethered to every minute of every day. There are some people like me who enjoy that. Not going to lie. Been wearing CGM for almost six years. It never gets old to me. I continue to find insights that just provide value. And more than anything else, it's really the behavioral tool. And that might make me a mental midget. I might just be a guy that is such a simple plebe that having that little CGM on my arm is what keeps me away from the ice cream in the freezer and the cookies in the pantry. But if you saw my freezer and you saw my pantry, you would certainly understand why I stand to benefit from using cgm.

I think you mentioned this in the article or the Sunday Post about how the percentages change with. When you talk about how much insight you're getting, say in the first 30 days versus long term, whether it's a motivational or behavioral tool and how those can shift. But I also want to mention that when I was at uvm, I was getting my undergrad and I was studying nutrition. That to your point about ice cream in the freezer? I remember for one of our courses that we were taking, we started doing a food logger food diary. And I remember at the time I was eating. I don't know why I got into this, but actually you probably will know why. I was eating a pint of Ben and Jerry's chocolate chip cookie dough just religiously.

Is a pint the one that's this big, like the little one? Is that a pint?

That's the 16 ouncer. Yeah, but I think that's the only thing that Ben and Jerry's comes in.

Okay, okay. And you were eating one of those a day?

I was eating one of those a day after dinner. And it was just like whatever kind of habit. Then I was doing the food log and I had to keep a food log. And that's how I kicked that, if you want to call it a habit. That's how I kicked the Ben and Jerry's habit. I said, look, I'm going to have to write, I think it's two days during the week and one day during the weekend that I had to do it. And that's, I think, typically what they do for food diaries. And you just log everything you eat real time over 24 hours for a Monday and a Thursday and a Saturday. And I remember I kicked that habit. But it reminds me of this stuff, that some of these things are behavioral tools, maybe in disguise. But I think you mentioned something like 9010 at the beginning with your.

Yeah, yeah. And that's sort of what I tell patients. Because, look, a lot of our patients are like, hey, Peter, what do you think? I mean, do you think I should do this? And my answer for most of them is, yeah, I think you should. I think everybody deserves a three month trial of cgm again, notwithstanding a handful of patients who I think have contraindications. And I typically say, look, it's gonna start out as about 90 10. 90% of this is gonna be insight. Like you're gonna be going, holy cow, I can't believe. Fill in the blank. And only 10% of it is gonna be changing your behavior through this Hawthorne effect. I said, by the end of that 90 days, that's gonna flip again. It depends on how much insight you look to extract, but Dictirectionally, within about three months, you're gonna be like, you know what? I sort of figured out the effect of grapes and the difference between a grapefruit and a banana. I've kind of got that dialed and I've also figured out that I can eat a ton of carbs after I work out, but if I eat a ton of carbs before bed, totally different effect on my blood glucose overnight and in the morning. But the shift is, you start to gamify it a little bit. So, yeah, I guess that's sort of what I would say on my framework for how to think about these things.

Okay, so related questions to cgm. I've got. Actually, you just mentioned grapes. So this, this person says, my glucose spikes when I eat some fruits but not others. Do you know why this happens? And does it mean that I should avoid fruits that spike my glucose?

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