Dr. Gabrielle Lyon: Why You’re Not Overfat, You’re Actually UNDER-MUSCLED!

Añadido: 2026-05-16

[00:00:00]Gabrielle Lion, welcome.

[00:00:02]>> Thank you so much.

[00:00:04]>> So great to have you here. You have a tremendous range and depth of expertise.

[00:00:10]You treat men, you treat women, you know a ton about exercise physiology, nutrition.

[00:00:18]You've done work in psychiatry. You've done work in geriatrics.

[00:00:22]You know so very much about how to get healthy and stay healthy. And today we're going to talk about all of that.

[00:00:31]To kick things off, I would love to dive into your take on this unique aspect of our physiology that most people when they hear about think about weight training or maybe bodybuilding or have some immediate reaction to, but you have a different stance on this incredible organ that we call muscle.

[00:00:55]So if you would just tell us how you look at this thing that we call muscle in men, in women, in kids, in old people, young people, how should we think about muscle?

[00:01:06]>> Well, first of all, muscle is the organ of longevity. And we've always thought about muscle just as you said when it comes to exercise, performance, mobility, and strength, which by the way, all of those things are important and critical for life. But there's something very unique and special to skeletal muscle. First of all, it's an organ system. It's an endocrine organ.

[00:01:28]It is responsible for a large component of glucose disposal. Roughly 80% of glucose disposal. And we all hear about these things like cardiovascular disease, type 2 diabetes, obesity.

[00:01:42]Largely, many of these metabolic diseases begin in skeletal muscle decades before.

[00:01:48]>> Interesting.

[00:01:49]>> Skeletal muscle is also an amino acid reservoir. It is the place that your body pulls from amino acids and that is um something that changes as we age.

[00:01:59]This idea of protein turnover and we require healthy skeletal muscle. Of course, it's the body armor that we all know and it is really responsible for how we age. And by the way, I came to this understanding through um an experience I'd love to share with you. I did my fellowship in geriatrics and nutritional sciences. And at the time we were looking at, you know, every fellow has to have a project, lucky for us. And we were looking at body composition, brain function, and there was one patient who I just adored. She was a mom of three kids, and she had always yo-yo dieted. We image her brain, and her brain looked like the beginning of an Alzheimer's brain. And I thought to myself, and I felt very responsible, thinking, why was this woman who was doing everything that we told her to do, she was exercising, she was eating a low-fat, high carbohydrate diet, why was she so metabolically unhealthy?

[00:03:01]And I realized that at the end of the day, it wasn't that she was overfat, it was that she was under muscled. And we spend decades and have spent decades trying to treat obesity when really what we need to be looking at is skeletal muscle.

[00:03:16]>> Super interesting. We know that the brain is among the most metabolically active organs in the body and muscle too, one of the most metabolically active organs in the body. You'll probably tell me that one is more active than the other. Which one is it? M >> muscle is actually quite frankly not very metabolically active at rest.

[00:03:33]>> Interesting. For every pound of skeletal muscle, it might at rest burn 10 calories primarily burns fatty acids at rest.

[00:03:41]>> Okay. I learned something new and I imagine many other people did as well.

[00:03:44]>> So this woman that was overweight >> Yeah.

[00:03:47]>> Um you looked at the problem through a different lens that she's under muscled.

[00:03:53]How does one go from being under muscled to properly muscled and what is that?

[00:03:58]And as I say this, I realize that many of our listeners probably don't resistance train or if they do, they may not want to carry a lot of muscle thinking that that would make them have to buy a new wardrobe. You know, certainly some of our listenership probably wants to gain more muscle, but is >> or a new wardrobe or a new wardrobe. Is there a way to view increasing muscle mass in a way that is compatible with kind of um I don't know we call like a traditional aesthetics or um with overall health in a way that's sort of distinct from quote unquote bodybuilding. I mean again as soon as we talk about muscle we think about slabs of meat added to different parts of our body and surely certain people probably want to add muscle to certain parts of their body for aesthetic reasons.

[00:04:47]How should we think about muscle in the context of some of the todos um in terms of nutrition and exercise? And we'll segue into that again. How should we conceptualize this business of being under muscled and getting to I guess what we call appropriately muscled. Uh I think that that's a it's a really good point. This idea of being appropriately muscled. So the truth is I can't tell you how much skeletal muscle mass you should have for optimal health. I don't know how much skeletal muscle mass I should have for optimal health. We haven't done a good job in the literature and just as a population being able to track skeletal muscle and know what is optimal. We are really good at looking at body fat and we're really looking good at looking at bone. But when it comes to skeletal muscle, DEXA is an extrapolation. So for example, we use DEXA as the gold standard. And I'm going to come back to what we need to do to gain healthy skeletal muscle. But I think that there it's really important to put things into perspective and a framework for how we think about things.

[00:05:47]We traditionally use DEXA. DEEXA looks at bone and it looks at lean tissue collectively. Part of lean tissue is skeletal muscle mass. It doesn't determine the health of skeletal muscle mass. It doesn't determine anything about the quality of that tissue. It purely looks at lean tissue which then we determine part of that lean tissue.

[00:06:09]Maybe it's 40% is skeletal muscle. And that's important to understand as we begin to frame up the conversation is how much skeletal muscle should I have?

[00:06:18]I have no idea. But what I can tell you is that if I were to look at your blood work and I saw something like elevated triglycerides or elevated insulin or elevated glucose, I would begin to understand that the health of your skeletal muscle isn't where it should be. And by the way, the health of skeletal muscle mass begins when we're young. This idea of sarcopenia, which for the listener or the viewer, the definition of sarcopenia, by the way, became a disease. It wasn't even classified as a disease till 2016.

[00:06:53]>> Wow.

[00:06:54]>> Yes. Wow. Which is very recent for a disease. It is a decrease in muscle mass and function.

[00:07:03]But interestingly, we don't necessarily know what one should have. So, I think it's important to understand that when we're talking about the health of skeletal muscle, we're still pretty much in the infancy of understanding the trajectory of of where it is and where it's going. So, when we think about how we maintain the health of skeletal muscle, one of the things that I I didn't mention is that skeletal muscle is a nutrient- sensing organ.

[00:07:27]It is uniquely sensitive to the quality of our diet. The quality of our diet defined as the quality of the amino acids that we're gaining. And that would be for the listener dietary protein.

[00:07:40]Skeletal muscle is sensitive to one of the amino acids, leucine. And depending on the quality of the diet, meaning how much leucine that you're getting in any given meal will then stimulate muscle health.

[00:07:52]>> Not just muscle size, but muscle health.

[00:07:54]>> Muscle health. And the way that we think about muscle health is by proxy is this this concept called muscle protein synthesis which we can measure. And when we get a dietary protein amount which is between 30 and 50 grams of high quality protein it stimulates skeletal muscle.

[00:08:15]So I love this idea of focusing for a bit on muscle protein health because it divorces us from this conversation at least temporarily about muscle size which of I have to imagine is correlated but it's a separate thing alto together actually I should just ask the question is it possible for somebody to have a lot of muscle but their muscle health is poor >> yes >> okay conversely can somebody have a moderate to low amount of muscle but their muscle quality is high or is that less moment.

[00:08:44]>> Um well the the first thing that you said is is absolutely something that we see is that in an individual that carries a lot a lot of muscle and say they're inactive. There is a big discussion about how um heavy individuals will have more muscle mass.

[00:09:01]But what we have to recognize is the health of that skeletal muscle is fat deposition can be visceral fat deposition fat around the organs and it can be also fat infiltrate into the tissue like not to gross anyone out a marbled steak.

[00:09:15]>> And that's exactly [clears throat] what can happen to unhealthy skeletal muscle which then affects its ability to contract which also affects there's a ton of mitochondria in skeletal muscle.

[00:09:25]It affects the efficiency of skeletal muscle. So yes, someone can have potentially more muscle but more unhealthy muscle.

[00:09:32]>> Interesting. When you say um a marbled steak, I think at the extreme a wagyu >> um a raw wagyu looks like there's as much white fat in it as there is red meat in it. Um and it's a very different taste and texture. So that's what we're talking about. My understanding is those cows uh don't move around much. Um they're somewhat sedentary compared to say a freerange grass eating cow. Oh, is that right? Okay, >> that's that's absolutely correct.

[00:09:59]>> Okay, so we want we want quality healthy muscle and then we can talk about muscle amount.

[00:10:05]>> And then the other thing that I'll say about it is part of what defines muscle health is that flux, that movement. So if you were to think about skeletal muscle like a suitcase and an individual was say going on a trip for 4 days but chooses to eat or pack for 30 days.

[00:10:23]>> We know these people. Yes, I know I'm maybe one of them. I have my suitcase here. I was only coming in for a day, but I may have packed for four days. Not sure what I was doing, but uh that's besides the point. When an individual is overeating calories, overeating carbohydrates. I had mentioned earlier that skeletal muscle, one of its primary roles is glucose disposal, and I'm sure we're going to get in the mechanisms of glucose disposal, whether it's um insulin dependent or insulin independent, depending on if someone is moving or contracting that muscle. When an individual is eating food carbohydrates, it gets stored in skeletal muscle as glycogen because as we know glucose at a high level is toxic to the body. So the body must move glucose out of the bloodstream into the the cells. Now what happens is is there becomes this stasis.

[00:11:16]So if an individual is inactive and not exercising then that skeletal muscle becomes overpacked. Uh skeletal muscle at rest burns primarily free fatty acids which is interesting. Most people think about skeletal muscle as burning carbohydrates but actually at rest skeletal muscle burns fatty acids. As you can imagine, when that muscle is full and you are not exercising it, then the substrates have nowhere to go and it remains in the bloodstream and that would be a sign of unhealthy skeletal muscle, which then loops back to what you see in blood work.

[00:11:52]>> Elevated insulin, elevated blood glucose, >> elevated free fatty acids, elevated branch chain amino acids, all of these things which again as skeletal muscle as the metabolic sync have nowhere to go.

[00:12:04]So I'm starting to get a picture where in order to have healthy muscle, we need to think about the feeding of that muscle, the providing of nutrients to that muscle that is as well as the use of that muscle. Maybe let's start with the feeding or the providing of nutrients to that muscle. You mentioned that muscle at rest mainly burns fatty acids. It can store glycogen. How do we know when a muscle is full of glycogen?

[00:12:29]I mean there's the the visual uh representation of the muscle seems fuller as opposed to flatter um you know but these are um not specific um or these are not um precise terms you know how much carbohydrate does it take to fill all the muscle of the body with glycogen and then what sorts of things perhaps deplete that >> I think it's a great question we know that when we're talking about glycogen the the liver stores glycogen maybe 100 grams and then skeletal muscle depending on your size. For example, um you might store much more muscle glycogen whether it's four or 500 grams compared to someone who is my size.

[00:13:07]>> And can we do the the standard conversion of four calories per gram? So if the liver is 400 gram, you know, we just say, okay, there's about 1,600 calories worth of energy there. So if I if I go out and I uh do some exercise and burn, 1600 calories over time, does that mean that the the liver is then completely depleted? So well the liver will deplete in through an overnight fast. So the liver's m the liver maintains blood glucose. So skeletal muscle doesn't maintain blood glucose directly. The way that you would leverage uh muscle glycogen would be through exercise.

[00:13:41]>> The way in which you would deplete muscle glycogen would be through more um intensive exercise. And when you think about the foods and the way in which you know your original question is how would we know how much muscle glycogen or how much we need to refuel I typically think about it as overall activity levels. So if someone is sedentary then the current recommendation for carbohydrates would be 130 grams a day per day per day >> at four calories per gram >> at four calories per gram.

[00:14:11]>> And is that um both simple and complex carbohydrates fibrous carbohydrates?

[00:14:15]>> Yes. would just be overall >> 130 g if they're completely sedentary.

[00:14:19]So just a little bit of walking, getting up, going to the computer, to the bathroom, to the car, etc. But basically sedentary.

[00:14:25]>> Yes. And the average American takes in 300 gram of carbohydrates a day. So more than double. And as you can imagine, this can distort metabolism. When we think about glucose disposal, the way in which I think about glucose disposal if an individual is sedentary is thinking about how many carbohydrates an individual can ingest at one time that would mitigate insulin response and would be able to be disposed of safely.

[00:14:56]And that number is between 40 and 50 grams of carbohydrates at a meal outside of exercise. The rest of carbohydrates would be earned through exercise and through every hour of exercise, depending on the intensity, that could be between 40 to 70 grams, depending on how intense an individual exercises. And that would be safely disposed of in a 2-hour period. I mean, when you think about an oral glucose tolerance test, that's a 75 gram load. you assume within two hours that that blood sugar regulation should come back to a normal range.

[00:15:35]>> So at 40 to 50 grams of carbohydrate every 2 hours, does that mean that if somebody were to eat 40 to 50 grams of carbohydrates every 2 hours, >> which they shouldn't, >> which they shouldn't, but you're going to quickly exceed that 130 grams per day. And even if exercising with resistance training say hard for an hour um which get you know can afford somebody maybe what another couple hundred 300 grams of carbohydrates >> probably not that much.

[00:16:03]>> Okay. Uh, you know, I I think that if people care about body composition, >> which um I would say everyone should because you want to have an appropriate level of body fat and healthy skeletal muscle, then you wouldn't necessarily unless you're doing some kind of cardiovascular activity, you're not using a ton of of muscle glycogen depending on how much you're training.

[00:16:25]>> And how much glycogen is the brain using?

[00:16:29]>> So, that is a that is a good question.

[00:16:31]um the brain uses um a lot of carbohydrates. That would be the a primary source. When they come up with the numbers of 130, it's really based on brain and then the rest of the the body.

[00:16:45]>> Can we safely say that for somebody that's thinking a lot, they need more carbohydrates?

[00:16:50]>> Um you could say that then your brain, yes, your brain is very metabolically active.

[00:16:55]>> Interesting. So, we're kind of drawing rough estimates, not knowing people's body weight, not knowing their body composition. But what I'm arriving at here is, you know, if somebody does a little bit of cardiovascular training, maybe a little bit of light resistance training, I'm describing the activities of many people out there, maybe 250 grams of carbohydrates, you're kind of at the threshold. That's a lot.

[00:17:18]>> That's That's a lot. Four four calories per gram um of those carbohydrates. And so let's say 200 grams of carbohydrates per day. Um but that's not a ton of calories overall. So what should the remainder of the calories be made up of?

[00:17:33]>> So you know I think what we're really talking about here is how do we design a nutrition plan >> for people to have healthy skeletal muscle?

[00:17:40]>> Right?

[00:17:40]>> And you know if I were to say okay what are we thinking about for the listener or for the people out there? they're thinking, you know, I really want to have a healthy body composition and healthy skeletal muscle mass. The way in which they would do that is number one, you have to prioritize dietary protein.

[00:17:58]So, we're we're talking about carbohydrates here, but carbohydrates shouldn't be the primary focus. Nobody has challenges getting carbohydrates in.

[00:18:06]130 grams would be a safe recommendation. If it someone is overweight or struggles with type 2 diabetes or any of these other metabolic conditions, there is evidence to support a lower carbohydrate intake.

[00:18:18]>> I mean, 130 grams is, you know, one little micro packet of pretzels on an airplane ride, you know.

[00:18:25]>> So, that that actually has probably closer to 37 grams of carbohydrates.

[00:18:29]>> Okay, good.

[00:18:29]>> Not that I had a pretzel packet before or threw one at Rob on the way in, but no.

[00:18:33]>> Right. Uh, okay. So, I'm way off there.

[00:18:35]Um uh so they have a one of those a bagel in the morning >> and um they shouldn't but they uh but they do and then they have some you know pasta at dinner and so most people are probably exceeding that 130 gram by a huge margin.

[00:18:52]>> Yes, they are. And um there's a couple things there that it's really important that you said is that individuals when we're thinking about designing a plan for skeletal muscle health that first meal is most important. that first meal of the day, having dietary protein will set you up metabolically for the rest of the day.

[00:19:10]>> And when you say first meal, and we'll talk a little bit later about intermittent fasting, and you know, I, for instance, eat my first meal at usually 11:00 a.m. It's just kind of how I'm wired. I've never wanted to eat breakfast first thing. I've forced myself to eat some eggs first thing in the morning from time to time, and it felt fine. But do you recommend that people eat a true breakfast like within a certain number of hours of waking up for sake of muscle health the and and metabolic health?

[00:19:37]>> When we think about um that first meal, I frankly don't care when you have it.

[00:19:42]One also has to understand that you're coming out of an overnight fast. If you are young and healthy, then the timing of that first meal likely doesn't matter because you are robust.

[00:19:53]your body is very efficient and capable to withstand um protein degra degradation. It's able to withstand protein degradation and protein turnover, which is ultimately why we're eating. So, that's one reason why we're eating. And we'll talk a little bit more about that. That first meal of the day, if you are young and healthy, the timing doesn't really matter. And I would say when it begins to matter is when you're older. When you are in your 60s, fat, continuing to fast may be a negative a negative for muscle muscle health. That first meal of the day is important because we know that when you get between 40 and 50 grams of protein, that first meal of the day, you stimulate muscle protein synthesis. Muscle protein synthesis is by proxy what we use to measure um as a marker for overall muscle health. Now there's a lot of history here when we think about designing a a meal plan. That first meal has between we'll say give it between 30 to 50 grams of dietary protein that will do a number of things. Number one, it will stimulate skeletal muscle, what we would consider the health of skeletal muscle. It also will affect the brain.

[00:21:08]It'll improve satiation. You and I were talking previously. It releases um a handful of uh gut peptides >> like glucagon, like peptide one which later we'll talk about mjaro py things that will affect appetite uh for that second meal and this there's some very interesting research out of Heather Leidy's lab and basically when she put individuals younger uh adolescents on a meal of 30 to 40 grams of protein they were much less less likely to choose say donuts or something uh outside of what we would consider a healthy nutrition plan >> later in the day or in the same meal >> later in the day. So um >> it was essentially augmenting their willpower.