The Peter Attia Drive - #227 - AMA #40: Body composition, protein, time-restricted feeding, fasting, DEXA scans, and more

Episode Date: October 17, 2022

View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content Sign Up to Receive Peter’s Weekly Newsletter In this “Ask Me Anything” (AMA) episode, Peter discusses the importance of understanding body composition and explains how to interpret the most important metrics revealed by a DEXA scan, such as lean muscle tissue mass, visceral adiposity tissue mass, bone mineral density, and more. He discusses common concerning trends in these metrics as well as strategies to address them. He goes through DEXA scan results of both male and female patient case studies and explains the prescribed intervention for each patient. Additionally, Peter answers numerous questions about dietary protein including how much we need, when we need it, and how intake should be divided throughout the day to optimize muscle protein synthesis. Finally, Peter provides his updated point of view on time-restricted feeding and fasting and how his personal approach and recommendations for patients has evolved. If you’re not a subscriber and are listening on a podcast player, you’ll only be able to hear a preview of the AMA. If you’re a subscriber, you can now listen to this full episode on your private RSS feed or on our website at the AMA #40 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here. We discuss: Interpreting DEXA scans: important metrics, radiation levels, and more [2:15]; DEXA metrics: Bone mineral density (BMD) [12:00]; DEXA metrics: Visceral adipose tissue (VAT) [14:30]; DEXA metrics on lean tissue: appendicular lean mass index (ALMI) and fat-free mass index (FFMI) [20:45]; Concerning trends in BMD, VAT, & muscle mass revealed through DEXA scans [24:15]; Muscle and lean tissue loss with age and how to overcome anabolic resistance [29:15]; Female patient case studies: DEXA scan results and prescribed interventions [35:00]; Male patient case studies: DEXA scan results and prescribed interventions [42:45]; Protein consumption: recommended daily intake, Peter’s personal approach, timing around workouts, and more [48:15]; What to look for with protein supplements [53:15]; Protein intake: optimal timing and how it should be divided throughout the day [55:30]; Time-restricted feeding (TRF): Peter’s updated perspective [57:45]; Three strategies for reducing energy intake in over-nourished patients [1:03:15]; Prolonged fasting: potential benefits and tradeoffs [1:07:15]; A protein-supplemented version of time-restricted feeding (TRF) [1:09:30]; Theories about time-restricted feeding (TRF) and its positive influence on sleep and circadian rhythm [1:12:00]; and More. Connect With Peter on Twitter, Instagram, Facebook and YouTube

Hey everyone, welcome to a sneak peek, ask me anything, or AMA episode of the Drive Podcast. I'm your host, Peter Atia. 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 peteratia MD dot com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. Welcome to Ask Me Anything episode number 40. And once again, joined by Nick Stenson. In today's episode, we talk about how to interpret

Dexascans. We've had a lot of questions about this. I've talked about it on and off in various podcasts, both my own and being a guest on a few other podcasts. So we decided to kind of go through this in the exact way that we go through with our patients. So what are the four things that a Dexascan tells us and how do we interpret

each of these things? We then go through, I think about four patient case studies, each of which is illustrative. Again, the likelihood that you will find something of yourself in at least one of these is very high and I think justifies going through all of them. We then kind of talk about protein because one of the things that comes out of interpreting the dexascans is how do we assess a person's lean tissue and what we need to do about it. So then kind of answer a whole bunch of questions that came in about protein. How much do you need? When do you need it?

How should it be divided throughout the day? We then close the discussion out with a revisit of time restricted feeding. I've made some comments in the past. I think most recently on the Strong Conv held episode where I talk about my changing views on TRF. And I wouldn't say it's that I'm saying that one should never do TRF, but I have a much more nuanced view of it today than I did five years ago.

And I go through both the recent New England Journal of Medicine paper that came out earlier this year that generated a lot of controversy and then add a lot more color to it, including a discussion about circadian rhythm and the relationship of food on the ability to sleep and even some brain health stuff. So if you're a subscriber and want to watch the full video of this podcast, you can find it on the show notes page. And if you're not a subscriber, you can watch a sneak peek of the video on our YouTube

page. So without further delay, I hope you enjoy AMA number four. Peter, welcome to another AMA. How you doing? Doing very well. Excited to talk about this stuff today. Awesome. I don't know if you noticed, but I saw your Instagram post today on Maui, Newly, Medicine. So I wore my Axis Dear Institute shirt. I wonder if that was a coincidence, but the accidental experts love that story.

So for today's AMA, it's not going to be on exercise like the past to have been. We're going to stick to that. Although I'm sure some of what we'll talk about will tie in a little bit to exercise, but what we're going to do is we just kind of gather a ton of questions all around basically body composition in one way or another. So we're going to start by looking at Dexascans. This is a topic that has come up a lot in AMAs recently, especially the bone health AMA. And we've gotten a lot of feedback from listeners who they're like, hey, I went and got my dex results. I'm trying to understand what they mean. How should I think about them? What matters? What doesn't?

So we kind of compiled those and we're going to do a deeper dive into that, including looking at some real life patient case studies. So what we had is the team pulled specific patients that you have. And we thought we're kind of good over-arching studies that kind of show people how they can think about this, and then also what changes need to be made based on those results. So kind of not only how to understand the DexA, but then how you apply that to your life. And then from there, we're going to do some follow-up questions that mainly came from the Strong Convictions loosely, how podcasts and really around your comments on protein consumption and really how you get

as much protein in throughout the day as you want to. And then also some follow up questions on your comments regarding your views on time restricted feeding. So if it all goes according to plan, we'll wrap all that, but I think it will all kind of fit together because I think a lot of what we'll talk about in the protein, time-restricted feeding will play off what we learn in the DEXA.

So with that said, anything you want to add before we kind of jump into the first question? Nope, let's go for it. Perfect. So the first one, keep it simple, just how should people interpret their DEXA scans? So when your patients do them and you do them and you look at the results, what do you care about, what are you looking at, and even what metrics are they providing that you don't care about? Probably first I should explain what a dexascan is for folks.

So a dexascan is an x-ray. Basically, it's sort of a moving x-ray. So you lay on a table and a really, really low powered X-ray. So meaning very little ionizing radiation is sort of run across your body. And the way all X-rays work, basically, is there's a plate behind the object or the person being X-rayed. And it's effectively looking at what's hitting the plate. And the more dense something is in front of the plate, the less electrons that are going

to hit the back of the plate. Now there's a unit in radiation that we talk about, and it's usually milli-seavers. We talk about how many milli-se-verts of radiation something offers you. And more radiation to some extent is harmful. And so the NRC recommends that a person receive no more of 50 mille c-verts in a year, in a calendar year. So the question is then, how do you put that in context, right? So just living at sea level is something to the tune of one to two millisieverts per year.

So just being exposed to the sun at sea level, not just the sun, but of course everything that's ionizing in space, basically it exposes you to two, three, maybe four percent of your annual allotment. And that changes. So if you lived in Colorado, you know, where you're basically a mile above sea level, it's about twice that amount that you're getting. But when you start to look at something like a flight, like what is an east coast to west coast flight, well, you know, it's a certain amount of radiation. It's not nearly as much as if you're going over the poles. But now you have to measure those things in micro seaver. It's that's how much lower it is. So a flight would be like 40 micro seaverts. And again, a micro seavert is 1 1 1 1 1 1 milli seavert. What about a mammogram? So a mammogram would be about 400 micro seaverts or 0.4 milli seaverts. Chest x-ray, depending on the size of the individual, maybe 25 to 50 micro seaverts.

Conversely, a CT scan of the chest abdomen and pelvis could be up to 20 million severs, which would be about 40% of your animal alive. So why am I saying all this? Well, I just want to put DexA in context because it is a virtually radiation-free technology. It is insanely low. I won't get into all the details of why, but it's typically less than 20 micro-seaverts. That's sort of the punchline. So, AdexA has no more radiation than even the lowest end of a chest X-ray, and we're talking about, gosh, like, one-twentyth of the radiation of a mammogram, and about half

the radiation of a cross-country flight. All of that is to say, AdeXA is a really safe, low risk. There's effectively zero risk to a DEXA scan. And it's not something you need to do that often. We have some patients when they come to the practice, they're ordering DEXA scans or they've been doing DEXA scans on themselves every six weeks.

That's a total waste of time. This is a type of scan that you would do once, maybe twice per year. It has the capacity to distinguish effectively three things, bone, fat, and other. Those are basically the three buckets that DexA is distinguishing, based on the density of what the electrons are going through. So when you do the scan, you basically get four pieces

of information. If you're looking closely at it, now again, when most people go and get a DexA scan, they're kind of looking at one thing, which is get four pieces of information. If you're looking closely at it, now again, when most people go and get a dexis skin, they're kind of looking at one thing, which is what's my body fat. And again, body fat can be calculated in two ways, but probably the best way to do it is to take the total amount of fat and divided by the total mass of the individual. And that gives you percent body fat. Technically, you can subtract out bone mass when you do that and get tissue fat percent. By the way, that doesn't differ very much because bones don't weigh that much,

just in case you're wondering where that discrepancy can be. Certainly, body fat is a relevant consideration. We'll talk about it. But I think there's three others that are more important. The first is actually BMD, bone mineral density. That is both reported in an absolute amount in grams per centimeter squared, and it's also reported in a z-score. Now, I think we probably covered a lot of this in the previous AMA on bone health, so I won't go into any more detail on that. The next thing that you get is an estimate of that or visceral adipose tissue. Again, I won't go into how this is done, but it is clearly just an estimate, and it's based on looking at the amount of fat that is in the torso above the anterior superior iliac crest and the ribs, and kind of trying to subtract out what it believes

is in the subcutaneous space, and therefore looking at the difference. And as you'll see, visceral fat is a relatively small fraction of total body fat, but it's important to get that right because it's so much more indicative of risk. And the final thing that it gives you is sometimes it does this directly. It just tells you the appendindicular lean mass index. And sometimes you just have to calculate it. And you can always calculate the fat free mass index

with both of which we'll talk about. So these are measures of how much lean mass you have or muscle mass in the extremities. And the way this is always reported is total amount of lean tissue divided by height and meters squared. So both appindicular lean mass index and fat free mass index, which is just total mass that is not fat divided

by height and meter squared. They're both reported there for in kilograms per meter squared. So those are the four things you get when you do a dexa. And of course, all of these things, you want to see how you stack up against a population. And that population is typically stratified by your sex and by your age. So therefore we have noograms for each of these things and that's how we present the data to a patient.

And that's how we therefore make decisions about where you rank and what you need to do. So to clarify on that, so the bone mineral density to that, AM, ALMI and FFMI, those are the four major things. And now, I think I've heard you say before, is not every place you get a Dexascane will give you those metrics, but every place will provide the metrics you need to come to the conclusion of that for yourself. With one exception, so there are some decks of places that only give total body Z-score for bone and they don't break it out individually by hip and lumbar spine. This is important because, again, I believe I spoke about this on the previous AMA, you can't make a diagnosis of osteophenia or osteoporosis or, frankly, assess BMD clinically without that feature. In other words, if you just look at total body BMD, the Z-score for the total body is too

easy to mask what's going on in those areas. So it doesn't mean you can't get a dexat one of those places. You can, but you just have to understand there's a blind spot, which is you're not getting adequate information about BMD. So if there's any concern about BMD, you're gonna have to go to a place that is able to give the segmented information.

Which is good for people to know just because as they're Googling different places and calling around, it gives them something specific to ask for to get a good understanding. Yeah. So on that, I think what makes sense to next is dive into each of those four metrics a little more and kind of what they mean and why they're important. With BMD, as you mentioned, we covered that in a BMD AMA, which was AMA 37 for anyone who hasn't listened to it, wants to go back and listen. I don't think we really need to dive into that in as much detail, just based on that AMA,

but the VAT, AL, MI, and FFMI, I think might be worth getting into, because I think those are metrics that most people aren't hearing about where body fat percentage, I think everyone is aware of that. They conceptually know what that is, but the other three, I think for people not in the space, it's a little outside of their understanding. Thank you for listening to today's Sneak Peak AMA episode of the Drive. If you're interested in hearing the complete version of this AMA, you'll want to become

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