The Peter Attia Drive - #136 - AMA #17： Body composition methods tour de force, insulin resistance, and Topo Chico

00:00:00.000 Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the drive podcast.

00:00:16.500 I'm your host, Peter Atiyah. At the end of this short episode, I'll explain how you can

00:00:20.460 access the AMA episodes in full, along with a ton of other membership benefits we've created,

00:00:25.440 or you can learn more now by going to peteratiyahmd.com forward slash subscribe.

00:00:31.120 So without further delay, here's today's sneak peek of the ask me anything episode.

00:00:39.140 Welcome to another ask me anything episode. This is AMA number 17. I'm once again

00:00:45.280 joined by Bob Kaplan and he goes by a little alias on this episode. In this episode, we dive pretty

00:00:53.480 deep into body composition. The question actually stemmed from, Hey, what's the best way to measure

00:00:58.700 body composition? But it digressed into what I think is a very comprehensive discussion of all

00:01:03.920 the different ways that you can measure body fat. And there are more than you probably realize

00:01:07.700 along with what it means. What's the difference between subcutaneous fat, visceral fat? What's

00:01:11.620 the optimal body fat? What are the strategies around improving your health? Is it better to do

00:01:17.280 it through a gain in muscle mass versus a loss in body fat, et cetera. And that takes up a heck of a

00:01:21.720 lot of time. And it really only leaves time for one other major topic, which is one around insulin

00:01:27.520 resistance. The question basically being, Hey, is insulin resistance reversible? Which of course

00:01:32.460 becomes a very long discussion and an opportunity, frankly, to showcase a cool little case study,

00:01:37.940 which I do. We close this one out with a little bit of a discussion on Topo Chico. So if my recent

00:01:43.800 email on Topo Chico piqued your curiosity, including my decision-making around it and what my potential

00:01:51.260 call it substitute agent is that I'm now mixing in with my Topo Chico and alternating with,

00:01:57.320 we talk a little bit about that. So without further delay, I hope you enjoy AMA number 17.

00:02:07.480 This is going to be a pretty cool AMA, but I actually thought I was doing it with Bob Kaplan.

00:02:11.700 Didn't realize I was going to be doing it with Mike Liute. What's going on here?

00:02:15.460 I'm donning the whalers caps. I figured that would be my alias today. That's usually when I check into 1.00

00:02:21.180 hotels because my popularity, my celebrity, I usually check in as Mike Liute.

00:02:28.460 There's bonus points to anybody listening to this who knows who Mike Liute is, but the fact that you

00:02:33.460 and I both immediately know, well, you know, of course, because it's your alias, but I immediately

00:02:38.020 recognize it. I don't know. Is that sad or?

00:02:40.960 It's impressive. I'm wondering how many people will know who the Hartford whalers are. 1.00

00:02:44.600 It's been a while.

00:02:46.580 Let alone who their goalie was circa 1984.

00:02:50.360 Yes. And who they are now. They still exist, but they moved and they changed their name.

00:02:55.160 Yes, indeed. So what do we have on the agenda, Mike, or should I say Bob for today?

00:03:03.220 We've got a bunch of questions and I batched them. I think that's as per usual into a few,

00:03:09.040 but we've got some stuff on body fat measurements. There's so many out there. What's the best type to

00:03:13.780 use? And do you have to buy your own DEXA or can you get away with some of the handheld or the

00:03:19.020 standup scales that do the, we'll get into that. Questions around insulin and glucose and insulin

00:03:23.880 resistance and whether you can reverse it. And then we got a bunch of questions around zone two

00:03:28.560 and then maybe more of a, well, not a rapid fire, but there are a lot of questions recently

00:03:34.520 about Topo Chico. I think more people will know what Topo Chico is than the Hartford whalers and Mike

00:03:39.960 Cliute. And then a couple other questions. One of the recent weekly emails was about colorectal

00:03:45.400 cancer screening. And there are a lot of questions that you could grill your GI doc or your personal

00:03:50.760 care physician. A lot of people are wondering, how do I do that delicately without them getting

00:03:55.040 upset? I think we should just dig in from the top, which is body fat measurements.

00:04:01.040 I mean, I think for context, it's worth explaining why one would even care about that.

00:04:05.100 We have a very crude measurement by which we can assess a person's health and it's called

00:04:11.060 weight. So you could stand on a scale, you can measure a person's weight. And if you juxtapose

00:04:17.740 that with their height, you can calculate something called a body mass index. And certainly the body

00:04:24.020 mass index is proportionate to health in some way, shape or form. So we generally know that people

00:04:31.020 with a body mass index in the vicinity of 20 to 25 are healthier than people with a body mass index,

00:04:40.740 say, between 35 and 40. That would be a relatively easy statement to make. But it doesn't really tell

00:04:48.080 us a whole heck of a lot between the difference body mass index of 22 versus 26, for example. Do you

00:04:54.060 know your BMI, Bob? I do. It's probably I am. You got to be 27, 28. Yeah, that's right. Probably

00:04:59.980 around 27, 28. Yeah. So technically you're, you're overweight, aren't you? I am technically. Yes, I am.

00:05:06.860 You are technically overweight, but as I look at you here on this screen today, you're a staggering

00:05:14.600 specimen of muscle mass. It helps my shirts off, right? Yeah, yeah, yeah. Of course we always do

00:05:22.600 topless podcasting only. So how do we capture that, right? So how is it that we've got Kaplan

00:05:28.980 over here at a BMI of 27 to 28, who, if you just went off an actuarial table, you'd say,

00:05:36.000 oh my God, we got to do something about this. And I've got patients who have a BMI of 22 and you'd say,

00:05:42.100 well, fantastic. High five, keep it up. But the reality of it is I'd much rather be in your shoes

00:05:48.000 than theirs. What's that difference? Well, obviously a big part of that difference is muscle

00:05:52.140 mass. And your muscle mass is such that your fat-free mass, I guess is a better way to describe

00:05:58.800 it, is the dominant part of what you are. And so your fat mass is actually very low. So most people

00:06:05.320 now, I think by having this discussion, have a sense of what we're talking about, which is what

00:06:08.800 percentage body fat are you? That becomes a much more interesting measurement. So to have a BMI of 27

00:06:15.480 at, you're probably at about 8% body fat, is a far healthier place to be than to be at a BMI of 22

00:06:22.860 with 24% body fat, the sort of skinny fat phenotype. So we'll refrain from digressing into all the

00:06:30.960 nuances of what all that means from a metabolic perspective, because I think your question was

00:06:36.120 just how do you do this? And the point here is you have to be able to measure body fat somewhat

00:06:40.660 accurately if you want to get to this next level of thinking. So there are lots of ways to do this.

00:06:47.880 Let's go through many of them, including ones that are really not necessarily things I'd recommend

00:06:53.220 for people. Think about doing the best one that you probably wouldn't recommend, which I think

00:06:58.240 is a cadaver analysis. That's the most precise.

00:07:02.040 The most precise would be burn calorimetry, where you would combust an individual after they were

00:07:09.040 deceased. And by measuring the constitutive amounts of oxygen consumed and CO2 released,

00:07:15.260 yes, you could get a pretty good guess of their body fat. So shy of that, amongst the living,

00:07:21.260 magnetic resonance imaging or MRI would probably produce the most accurate results. I have only had

00:07:28.660 one body fat test in my life done via MRI or two, but it was part of an experiment I was participating

00:07:34.220 in. So this is not something that is a typical indication for MRI. It's usually done in the

00:07:43.200 research setting. Did we ever do an AMA on how MRI works? I think Raj was on the podcast. So

00:07:50.820 that's right. That's right. He dug into it. This is probably getting ahead of myself, but

00:07:55.280 one of the things we're going to look at is DEXA, which is an X-ray, but people will often get that

00:07:59.740 to look at their bone mineral density. And you can also get body fat. I think a lot of people will go

00:08:04.360 in for their bone mineral density and the software package will spit out and it'll tell them what

00:08:09.460 their body fat percentage is and all that other stuff. We can get into that. But I'm curious with

00:08:13.000 an MRI, when you get into an MRI, if you go into for an MRI and for another reason, you're not also

00:08:18.120 going to get as part of that package. Oh, by the way, here's your body fat percentage. 0.58

00:08:22.420 Very rarely do people go in for a whole body MRI. And even if they did, there would be a big software

00:08:28.480 look that would have to look specifically at the protons within fat. It wouldn't be impossible.

00:08:34.120 And who knows, as time goes on, maybe more and more whole body MRI centers will be spitting out

00:08:38.740 that information, quote unquote, for free as the way you described it in other technologies. But again,

00:08:44.780 when most people go to get an MRI, it's, hey, my knee, my back, my this, my that, where you wouldn't be

00:08:50.240 able to capture all of those data because a whole body MRI is a stupidly time consuming process unless

00:08:55.960 you're doing it via one of the very, very, very few technologies that can do it in under an hour.

00:09:01.540 Most typical commercial grade scanners would take four to six hours to scan the whole body.

00:09:06.740 All that said, let's not get into how MRI works. It's the gold standard. And the reason it's the gold

00:09:12.660 standard is not just how accurate it is, but frankly, that it gives a very, very clear picture of

00:09:20.240 where said fat is. And this is a point worth mentioning. Not all fat is created equal.

00:09:25.340 I think for the purpose of this discussion, we can put fat into two buckets, though I really think

00:09:29.720 there's a third. We can divide it into cutaneous or subcutaneous fat, fat that is beneath the fascia

00:09:38.260 known as visceral fat. And I think most people have heard that term because most people probably

00:09:43.540 appreciate that visceral fat is the one you don't want. So it's one thing if you can't see the six

00:09:50.500 pack of abs. But to be clear, the inability to see the six pack of abs is really an issue of either

00:09:58.040 too small a rectus abdominis muscle group and or too much subcutaneous fat surrounding the rectus

00:10:06.720 abdominis muscles. No six pack equals one of those two things or a combination of them. But it doesn't

00:10:12.660 tell you what's happening beneath the fascia. So you have this corset that is holding you together

00:10:19.280 that is beneath your muscles, and it's called fascia. And it's inside that fascia that all of

00:10:24.340 your organs exist. And that's the place where you don't want to see any fat. Where this fat typically

00:10:30.760 shows up is around the liver, around the kidneys, around the spleen, around the gut. That fat is

00:10:38.140 incredibly associated with metabolic disease. If we were going to track people by some metric,

00:10:46.880 it wouldn't be BMI. It wouldn't be weight. Frankly, it wouldn't even be body fat percent. It would be

00:10:51.480 total amount of visceral fat in some normalized way. If everybody walked around knowing,

00:10:56.260 hey, I've got 6.3 pounds or whatever of visceral fat or 4.2% of my body weight is visceral fat,

00:11:04.600 and we tracked and managed that, holy cow, we'd be in a much better place. And MRI allows that. So it

00:11:11.160 can very clearly distinguish between these compartments. Also, something about MRI that's

00:11:15.960 fantastic, it's non-invasive, produces zero radiation. So you could MRI yourself all day long,

00:11:22.720 and you're not going to have that issue. Of course, on the flip side of that, again, I just think this is

00:11:27.280 a really new application for MRI, not necessarily practical, and obviously from a cost and availability

00:11:34.420 perspective, sort of not the way to go. Do you have like a ballpark of how much,

00:11:38.560 if I wanted to get an MRI, like next to my barrel sauna, I want to get an MRI machine,

00:11:42.460 how much it might cost? Sure, for giggles. So if you wanted to buy, so it's about a million bucks a

00:11:47.240 Tesla. So if you said you wanted to slum it and get a one Tesla MRI, which would be a super low-end

00:11:53.820 MRI today, that would cost you about a million bucks, plus hiring someone to run the thing.

00:11:59.860 I don't know. I don't think of it as a great investment, Bob.

00:12:02.480 It would be good at dinner parties, though, when somebody says, I have a Tesla. And then I'll say,

00:12:06.060 well, I've got a version of that too, as well, in the back. You could say, I've got a free Tesla.

00:12:11.160 I've got 1.5 Tesla. Yes, there you go. Which I think is the sweet spot. Okay. So moving down from

00:12:18.580 MRI, another way to measure body fat is actually to use CT scanning. So a CT scan is another type of

00:12:29.820 scanner that you get into, just like an MRI. They tend to be a heck of a lot faster. So you can CT

00:12:36.260 scan the whole body much quicker than you can do so with an MRI. And like the MRI, the CT scan does a

00:12:43.320 very good job of showing fat. So you very clearly get to see where the fat lies because it's a really,

00:12:52.920 really good anatomic study. And it basically can show you this is intra-abdominal, this is

00:13:00.100 subcutaneous. And so you, again, have that tool to kind of quantify not just how much fat the person has,

00:13:06.840 but more importantly, where that fat resides. Now here you have less of an issue on the cost

00:13:13.600 side, but the far bigger problem is radiation. And in fact, I would never recommend a whole body CT

00:13:20.000 scan. Honestly, I can't think of a single indication I would ever consider whole body CT

00:13:24.700 appropriate. And it's amazing because years ago there were all these places popping up on street

00:13:29.600 corners saying, Hey, come on in for your whole body CT scan to check if you have cancer, which is

00:13:33.960 the greatest irony of all because God knows how many cancers you were predisposing people to with

00:13:38.300 those things. I suspect that a whole body CT scan would be 50 millisieverts of radiation, which is

00:13:45.040 about the annual allotment that is recognized for a human being. And obviously you don't want to be

00:13:51.080 near the annual allotment on one day, but conversely just getting a CT scan of the chest, abdomen, and

00:13:57.760 pelvis, which lots of hospitalized patients need, it could easily expose you to 10 to 20 millisieverts.

00:14:04.280 I'd like to live my life in a sub 10 millisieverts per year environment if possible.

00:14:10.200 You don't want to be an astronaut, Peter?

00:14:13.540 That's a good question. I mean, somebody knows this. And of course, even though they're wearing

00:14:16.960 unbelievably protective equipment, do we know how many millisieverts someone would get a year at

00:14:22.300 the ISS? I think we do. I can look it up. We can include it in the show notes. We've got that chart

00:14:26.900 with a different radiation millisieverts. Yeah. Just standing at sea level for a year, you're probably

00:14:32.300 getting two to four millisieverts. And if you live at elevation, you know, if you're living in some

00:14:37.540 place like Denver, you're probably almost doubling that, but you're still well below 10. You want to

00:14:43.040 use CT scans judiciously and there's a time and a place for them, but measuring body fat ain't it.

00:14:48.420 Okay. You then alluded to something called DEXA, which sometimes goes by DXA. It's dual energy

00:14:58.820 X-ray absorptiometry.

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The Peter Attia Drive - November 09, 2020

#136 - AMA #17： Body composition methods tour de force, insulin resistance, and Topo Chico

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