Episode #388: Muscle Imbalances, Red Meat Risk, and the Science of Body Fat Set Points

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0:38Dr. Jordan Feigenbaum:So to start today's podcast, we are going to begin by challenging a common belief in the fitness industry, the idea that muscle imbalances are a reliable predictor of pain and injury risk. Here we explain why asymmetry is often a functional adaptation rather than a clinical problem, a feature, not a bug, and how a better understanding of the normal versus the pathological may change your approach. Let's get into it. Do muscle imbalances reliably predict pain and or injury risk? And how should coaches manage clients who dogmatically believe in these models? Oof, a lot of stuff here. Yeah, we'll go through it piecemeal.

1:19Dr. Jordan Feigenbaum:Starting first with just the basic premise, like do muscle imbalances reliably predict pain and or injury risk? And I think one way to look at this is kind of thinking about the differences between the normal and the pathological. so how would you differentiate between something that is quote normal and something that is pathological insofar as it either is representative of an injury or causing pain something like that versus a adaptation that we see in response to either exercise or in some cases even disuse right lack of lack of exercise and when we think about this or at least when i think about this through the lens of asymmetry i don't think that human bodies are naturally symmetrical you know you think about everything from like the muscle size from, you know, agonist antagonist pairings, and even the muscular strength, like quadriceps are stronger than hamstrings.

2:11Dr. Jordan Feigenbaum:Calves are stronger than your tibialis anterior and the muscles on the front of your lower limb, your triceps are stronger than your biceps. And so they're not symmetrical, like on either side of a joint, for example. So when people say, oh, there's an asymmetry, is it side to side? What they're talking about? Is it really agonist antagonist pairing? Um, and, and, you know, the, the literature is littered with examples of athletes across the, uh, compendium, you know, novice to elite levels that have massive quote imbalances and not only muscle size, but also anatomical features that you could see on like x-ray, uh, for example, on their dominant side, you know, tennis players, their dominant serving arm tends to be longer than their, their non-dominant arm.

2:53Dr. Jordan Feigenbaum:Um, if you look at rotational sport athletes, um, I'm thinking about like, uh, not, not only, uh, cricket players, but also like rowers. And you look at like their vertebral features on one side, you look at, uh, vertebral features and weightlifters, they have thickened vertebral end plates and thicker, uh, cruciate ligaments in the knees. These are all quote abnormal. If you were to just see them on imaging and they may not be the same side to side, um, but their features, not bugs. um and so i think if that's your base understanding of like should things be symmetrical front to back or side to side generally not it's not not consistent with like the human experience but people can have pain despite all of this right just like people can be asymptomatic despite being quote asymmetrical um so i think if i were really going to try to answer this very simply i don't care about asymmetry that much whether it's side to side or like an agonist antagonist pairing in most cases where i do start carrying is either post-operatively or post-traumatic injury i'm thinking about somebody who had an acl repair or somebody who you know tore a hamstring something like that and then you know side to side there's a huge difference in hamstring strength or lower extremity strength otherwise and at that point you're thinking we probably do need to do some specific work to to shore that up but outside of that sort of setting, either post-op or post-traumatic injury, rupture, tear, something like that.

4:21Dr. Jordan Feigenbaum:I just don't care. I don't know. What do you think about that?

4:24Dr. Austin Baraki:Based on what you have described, I'm imagining kind of three different trajectories that you can imagine people falling on and the amount to which their asymmetry, presumably in many of these situations, it's side to side. How much it matters depends on which of these trajectories you fall. One is it is an inherent asymmetry to you. Like in general, you know, one side might be a bit stronger or formed in a different way compared with the other, and it's always been that way. In those situations, when you choose to engage in a particular activity or sport, starting out with that basic asymmetry, it will either tend to maybe improve a little bit, depending on the demands of the task, or you will adapt to be able to perform the task with your asymmetry in place.

5:06Dr. Austin Baraki:So it is a longstanding, pre-existing sort of thing. You will either adapt one way or another, and it generally is not going to be a problematic thing for most people. The other situation that you described is maybe some of those kind of single-sided sport athletes, maybe they were actually started out more symmetrical before they engaged in the sport. And then the more of the sport they did, be it baseball pitching, they tend to usually throw with one arm or tennis players or other racket sports or rowers like our buddy, Dr. Miles, who only spent his life turning in one side of a boat and he has thoracic rotation much more in one way than the other.

5:42Dr. Austin Baraki:That is an acquired asymmetry, meaning over a longer period of time, that kind of coincided with the adaptation to the sport. That also tends to not be super problematic. The last trajectory where symmetry and asymmetry tends to be more of an important consideration is one where it is an acquired asymmetry, but it is much more abruptly acquired, right? It is not one that was longstanding before you ever entered the sport. nor was it one that you gradually acquired as you participated in the sport, but rather it was a more abrupt acquisition, meaning you suddenly had surgery and now you're now you're asymmetric side to side or you had a traumatic injury and now you're asymmetric side to side or you had a fracture or a neurological injury.

6:32Dr. Austin Baraki:And now you have, you know, differences in limb lengths or movement patterns or something else that you have not had years of, you know, existing with and exposure to and training with to adapt to or to develop as a natural course of your adaptation. so that's kind of the way that i'm framing this is like it maybe there's something to this idea in terms of the like how quickly it was acquired and acutely acquired asymmetry may have more of a risk of like too much too soon and then subsequent pain whereas one that was either long-standing pre-existing will generally be much less likely to be problematic and one that you acquire through the course of your training and performance is also unlikely to be problematic.

7:19Dr. Austin Baraki:And so we do have some material on this if you're interested, for example, in I think Derek's article is titled something to the effect of like when symmetry matters on our site. And it really is focused around, for example, his, you know, pet topic of ACL and post operative rehab. But that's kind of the way that I think both of us are thinking about this to where if somebody is experiencing some pain, for example, or an injury, and there was not anything else abrupt or acute about any of these changes, but we simply incidentally find some side-to-side differences that have probably been there for a long time or all along or have probably were even there before they even started lifting or participating in the activity.

8:00Dr. Austin Baraki:We're less likely to put a ton of attention on that compared with if they never had any issues, never had any pain, and then, oh, I got in this car crash and fractured my femur, and after surgery, my left leg is now two inches shorter than my right because of the way the surgery was done, which I have questions about that. So that surgery, and now I'm experiencing, well, it's like, yeah, your mechanics are like much more acutely different and it is much more your threshold or your tolerance, the too much too soon as much easier to hit when you have not been like long term exposed and adapted to that asymmetry in the same way.

8:32Dr. Austin Baraki:So hopefully that, that makes sense.

8:34Dr. Jordan Feigenbaum:Yeah. Yeah. So as far as how to do deal with this one, what if you're dealing with somebody who is firmly entrenched in this like asymmetry, you know, debate. And they really think that if someone is asymmetrical, either side to side or between, you know, various strength, strengths of muscle groups, that's what's causing pain and injury risk. I think you should be respectful, generally speaking, good, good, good advice, but also just ask for the evidence to support that. And you can, you know, weigh the veracity and the, the, you know, how that evidence was collected and generated and, and see if that makes, makes sense to you.

9:10Dr. Jordan Feigenbaum:You know, people are going to talk about upper cross syndrome, lower cross syndrome, a bunch of Janda stuff. And the evidence on that is made up shenanigans. You can observe things and then not necessarily prove that they have caused, you know, the end effect. We see that all the time. So that's for dealing with experts. Just ask for evidence. Roll that around in your head. And generally speaking, it's nice to at least know where other people are coming from. So you can kind of better appreciate their perspective. and further some some people that you might come in contact with professionally in the future and their their perspectives as far as clients go uh this goes all back to like communication styles i think validating how people feel initially right off the bat sort of helps build that rapport so you know you can say things like it's very common to feel tight weak in a particular area especially when you're in pain however we know that from looking at thousands of people that these differences are actually a normal part of being human you know and you're just more sensitive right now.

10:09Dr. Jordan Feigenbaum:So that's some reassurance there as well. You're not out of alignment right now. You're just sensitive, things like that. You could also mention instead of worrying that your left side matches your right side perfectly, let's focus on making both sides stronger. And that's typically the approach I type. I like to use where the squeaky wheel, so to speak, is going to get the grease. You know, if your right leg is, is not as strong as your left leg and you're doing split squats, for example, the right leg is going to get a different training stimulus than the left like. And this is more for like long standing sort of asymmetries, whereas the surgical stuff, you'll need some different loading.

10:43Dr. Jordan Feigenbaum:Doesn't mean the exercise is something you can't use. And most importantly, so as not to alienate the person who's in front of you is don't argue with them.

10:59Dr. Jordan Feigenbaum:Pretty interesting, right? Okay. Well, understanding the mechanics of the body and how it adapts is important for coaching, knowledge of what's going on under the hood or inside the body is important for long-term health outcomes. In the next segment, we're shifting away from the way our muscles look and work to the way our blood chemistry responds to nutrition and lifestyle. In this next segment, we're looking at the intersection of saturated fat, red meat, and the often misunderstood lean mass hyper-responder phenotype. Let's take a look at the evidence and go beyond the trending headlines.

11:35Dr. Jordan Feigenbaum:Next question, is limiting red meat and saturated fat necessary for someone who has otherwise optimal health metrics and a high fiber, high activity lifestyle? This is an interesting question because I think the crux of the question, the meat of the question, if you will, is, well, look, just how independently risky is red meat or are red meat and saturated fat? and to that i would say it depends how much you're eating of it and what does the rest of the diet look like i mean you know so it depends which is not a satisfying answer um so maybe let's back up a second i think when you compare these uh you know different dietary patterns things that are rich in red meat and higher in saturated fat to other dietary patterns particularly those that are plant-based and you just look at observational trials you know studies so where they look at different groups of people eating these ways over long periods of time large sample sizes you're going to see almost universally plant-based diets just win they just win and so you know vegetarians vegans people who like that that dietary pattern say see look at the data and on the one hand they're correct but not for the right reasons because a lot of that is is picking up what we call like a healthy user bias you know generally speaking people eat more plant-based diets not only uh they just tend to be fundamentally different from those who eat a diet that's high in red meat.

12:58Dr. Jordan Feigenbaum:They tend to exercise more. They tend to eat more dietary fiber, obviously, but they also tend to be more health conscious, generally speaking. Go to the doctor's office. Eating a plant-based diet also tends to cost more. So socioeconomic status differences, you can keep going down the line. There's just fundamental differences between the two, you know, avatars that we're comparing here at the level of observational data. So most of the health differences that you're seeing, you know, in those types of studies are just because the dietary patterns are so fundamentally different that that's what they're picking up and likely from a lot of other things that aren't just related to the dietary pattern as well.

13:37Dr. Jordan Feigenbaum:I think this question is more like, well, yeah, so let's eliminate all of that. And let's say in this particular case, the person eating red meat and a diet that's high in saturated fat, but everything else is optimized. well that doesn't absolve you from the risk of elevated you know atherogenic load you know uh so ldl cholesterol particles apolipoprotein b containing particles and i think we just have really good evidence suggesting that if those levels are elevated making changes to lower them would generally reduce risk of heart disease and so i mean i think that's the most simple answer to this.

14:19Dr. Jordan Feigenbaum:It's like, yeah, having everything else optimized, you're certainly in a better place than if they weren't, but you could probably get a little bit more optimized for some individuals if their apolipoprotein B test was high, for example, or if they had other additional risk factors or maybe not as modifiable, like elevated lipoprotein little a family history of heart disease where you'd want to be more aggressive potentially. I don't know. Is that how you, how you think about this?

14:43Dr. Austin Baraki:In, in a sense, I think that, you know, this, the way this question is framed is limiting it quote necessary and that idea of is it necessary really is something that requires the context of what are the person's goals are they one one of these folks who you're describing is like wanting to optimize everything to which i have several other questions for example like do you drink any amount of alcohol yeah because like if if all of this other stuff is perfect and that's your last question it's like well some of these other behaviors still might confer greater risk. The other way that I'm thinking about this is you're right, that by and large, the overwhelming body of evidence would suggest that continuing to substitute the red meats and animal-derived saturated fats for plant-derived protein sources and things like that is consistently likely to confer health improvements or benefits compared with going in the other direction.

15:37Dr. Austin Baraki:If it was just all correlational, it was all just messy, then you would see at least some weighting of evidence also going in the other direction among these healthy people. But pretty consistently, we see in various lines of evidence that substituting out those animal-derived saturated fats and red meats for plant-derived protein sources, a pretty consistent signal in the direction of health benefit. And so I think that the more of that that somebody is willing to do, the more benefit they are likely to derive. Although, as with most other things here, that benefit has diminishing returns, right?

16:13Dr. Austin Baraki:So if somebody is eating a ribeye a day, then substituting one of those out for something else is likely to give them, you know, a pretty substantial risk reduction. And then for each one from then on, all the way down to one a week or half a serving a week or a quarter serving a week or an eighth of a serving a week, you know, the incremental risk reduction that they get at those levels is less and less and less. And so I think it is probably uncontroversial between either of us and for many folks who are in our orbit to say that like yeah fatty red meats should not form a predominant it should not be a predominant element in your habitual dietary pattern if somebody is choosing to consume it on an occasional basis and they do not have any evidence of untoward health consequences like elevated blood lipids or other other factors like that then are they accepting some degree of risk compared with if they chose to substitute that out for salmon, for example.

17:09Dr. Austin Baraki:I would say, yes, it would probably be better if they were to substitute it for salmon. How much better? It might not be enough to make them motivated to do that just because of their preferences or their cultural, you know, food habits and things like that. In the same way that when we talk about is a cholesterol lowering medicine likely to lower your risk? Yes, that is actually the case for 100 % of the population essentially. But the actual amount of risk reduction is not equivalent for everyone across the board. It gives you a, say, 25 to 30 % relative risk reduction. Relative risk reduction means it depends on where your starting risk is.

17:48Dr. Austin Baraki:So if your starting risk is very high, you enjoy more benefit, or you're more likely to benefit. If your starting risk is super low, you're less likely to benefit. And so I view this kind of similarly. It might be the case that all your levers are maximally pulled in your health, and you're like, hey, can I just have like maybe a modest portion of a steak once a week or something like that? And I would say, you know, well, what are your what are your goals here? And if you want to have I want to live, I want to I want to Brian Johnson, this thing, I want to live forever, whatever. I'm like an aggressive optimizer.

18:21Dr. Austin Baraki:I'd say, yeah, I'd probably substitute that for something else. But if you're like, look, I'm doing as much as I'm willing to do to improve my health. And this brings me great joy and whatever, you know, trivial amount of risk it brings, I'm not concerned with because, you know, one other day of the week, I enjoy a glass of wine or something like that. And it's like, okay, well, you have determined the amount of risk that you're willing to accept. If you really want to like maximally pull every lever, you want to live, you know, that type of life, then yeah, probably would look at substituting that out for something else.

18:51Dr. Jordan Feigenbaum:yeah yeah there was a interesting paper that came out a few years ago where uh basically two experts arguing on either side of this like should we reduce the saturated fat uh target for uh americans in the food guidelines and you know currently it's a as far as your daily calories go eat less than 10 of your daily calories from saturated fat and on the pro side arguing yeah we should keep that in there maybe even consider lowering it it's like well look the if people consumed less saturated fat, particularly from red meats, most people are going to have a favorable response in their blood lipid level.

19:26Dr. Jordan Feigenbaum:And that's going to favorably impact their, you know, relative risk of cardiovascular disease. And on the other side, arguing against, they're like, look, the average intake, uh, as far as percentage of daily calories for saturated fat is 11%. So like, does it even need to be in there? Like who cares? No one reads the guidelines anyway. Yeah. Move on. Yeah. Um, and so, yeah, there's two sides to that argument. I think to maybe clear this up and really summarize this, we can talk about this lean mass hyper responder phenotype that's going around the interwebs. So this is a person who sees a significant rise in cholesterol, their blood lipids following the adoption of like a ketogenic or low carbohydrate diet.

20:07Dr. Jordan Feigenbaum:So the criteria that the people within that orbit that they say to be a lean mass hyper responder. You don't actually have to be lean, but your LDL has to go up in response to a low carbohydrate diet to greater than 200 milligrams per deciliter in associated with an HDL cholesterol that's greater than 80 and triglycerides that are less than 70. So effectively what this is saying is like your LDL is elevated. That's the only thing that's weird about your standard lipid panel. Okay. And they're saying, look, if this is you and you're eating a low carbohydrate diet, you're at no increased risk of heart disease because your triglycerides are low your HDL is high this is just an aberrant sort of relationship due to the nature of you following a low carbohydrate diet unfortunately the evidence on this is not very supportive of that hypothesis like you would have to just say like look the LDL being increased which we know carries apolipoprotein B and that is a good representative test of your atherogenic load which we know is like this time volume issue.

21:11Dr. Jordan Feigenbaum:The higher it's elevated, the longer it's elevated for, the higher the risk. You just have to say, nah, we're ignoring that in a specific case. Austin, what do you think about that?

21:20Dr. Austin Baraki:I think it's a bold claim, and I'm not opposed to people making bold claims if they, as you often say, bring receipts. And to date, they lack hard human outcome-based receipts. A lot of this is mechanistic kind of hypothesizing. They attempted to do this study that was popularized and went around the internet recently called the keto cta study that uh had a fair amount of problems with it and um led led to some egg on their face i think based on the speed of plaque development in people who fit this phenotype and so yeah it this is an area where um i have actually found it pretty straightforward to not get terribly worked up about it mainly because of the types of people who end up in this space.

22:07Dr. Austin Baraki:The people who end up in that orbit that you describe and subscribing to that view, they are people who generally are going to be pretty skeptical of a lot of medical advice, pretty contrarian in general. They are often heavy motivated reasoners in terms of trying to find ways to think about things that justifies their existing dietary patterns. And cool, like, you know it's your risk it's not mine my it i come back to this often of like here's my advice you're free to take my advice or if you want to go someplace else for someone else's advice like good luck hope hope it works out for you you know most people in that situation may well do perfectly fine because you have a lot of other health things going in your favor you don't have the atherogenic dyslipidemia phenotype where you have high ldl high triglycerides and very low hdl That is no doubt a higher risk type, right?

23:01Dr. Austin Baraki:That is the worst type. That is the one associated with insulin resistance, diabetes, things like that. The claim they are making is not that phenotype, but if you have high LDL and the others, HDL are high and triglycerides are low rather than the opposite, is that completely risk-free or is it just lower risk than the worst case phenotype? That's where I would be interested to see data. If you can show that people who have this lipid phenotype are at essentially equivalent risk to somebody who has the same phenotype, but just with low LDL, that would be actually kind of groundbreaking evidence because it would be in opposition to, you know, the vast majority of lipid data for the past century.

23:40Dr. Austin Baraki:So that's what I mean. Big claim needs some big evidence. And until we have that big evidence, you know, I'm not going to get too worked up about it. You can do what you want with your diet, your lifestyle. Good luck.

23:52Dr. Jordan Feigenbaum:Yeah. Big if true.

23:54Dr. Austin Baraki:Yeah.

23:54Dr. Jordan Feigenbaum:I definitely think you would predict that a person with just isolated elevated LDL would be lower risk but to say that it's no risk exactly it's equivalent it's saying like look a person with excess body fat and they're very fit and they're carrying a lot of muscle they're at no increased risk of medical problems from excess body fat and you're like well that's not true they're at less risk yes they have less muscle mass you know for example or less fitness but it doesn't absolve them of the risk of this well-characterized risk factor, same thing with blood pressure. So you just keep going down the line.

24:26Dr. Jordan Feigenbaum:You would prefer everything to be optimized if you were an optimizer. And so I think to just tie this back in, it's like, should you limit red meat and saturated fat? It really just depends on how, you know, what you're eating, how much of it you're eating, how that is affecting all of your risk factors and your, uh, you know, personal goals and, and like risk sort of tolerance. I think both of us would say that we're both tolerant of some risk related to red meat because we enjoy it. But if we were trying to maximize longevity, we would shift even further towards a more plant-based dietary pattern.