Hello, hello, and welcome to today's podcast. Today we're going to start with a question: in the last few years, do you feel like your metabolism has just kind of stopped cooperating with you? Are you doing all the same things and not getting the same response? You're more tired, your weight is shifting in ways that don't make sense, and your doctor says your labs are normal. What if we told you that the bigger part of what's happening actually has a name — and many people have probably never heard of it? That word is sarcopenia.
It's basically progressive muscle loss — where you lose muscle mass, strength, and function. It's a slow process that begins in our 30s and slowly progresses, about 1% per year. It's a small amount, so it's not something you can really tell from year to year, but over a decade it's noticeable. It's one of those things where you keep doing the same thing and you're not getting the results, or maybe you're getting weaker. And it accelerates in midlife — that's when we notice it.
The important part — why it matters — is that this affects all other forms of our health in general. We hope to explain how this process occurs and how it looks, so it's more of the "why" and the "what" we hope to describe today. This is part one in a series — we've got another part coming up in a few weeks where we'll sit down with a personal trainer, so tune in for that episode.
What Sarcopenia Actually Is
Let's establish the clinical foundation. Sarcopenia, from the Greek — sarx is flesh and penia is poverty, so "flesh poverty" — is essentially an age-related loss of muscle mass, strength, and function. Physical function happens secondarily to the mass and strength loss. This is very distinct from normal aging, although probably a lot of people just think of it as normal aging. The rate of your loss is heavily influenced by lifestyle, hormones, and nutrition — not just how old you are, not just the birthdays.
After age 30 is when this has been shown to slowly start to progress — we're all good until we hit 30, and then we slowly see a decline, and the less we do, the more significantly it shows up. It starts slow: in your 30s you may be losing 3 to 8% of muscle mass per decade, but once you hit 60, that moves up to 10 to 15% per decade. It accelerates if you're not doing anything to reverse it.
By the time most people notice this — reduced strength, slower metabolism, difficulty with stairs or activities they used to do, can't go up and down hills easily, can't carry the groceries in and out as easily, can't keep up with the grandkids — we've already lost 20 to 30% of our peak muscle mass, which was in our 20s.
How We Measure It
So how do we measure these muscle losses? There are a lot of options. The gold standard is a DEXA scan — the gold standard for body composition, which separates muscle, fat, and bone. It's likely the gold standard because it's been around a while; technology is up and coming, and there are a lot of other ways to test muscle mass now. A DEXA is a very low radiation dose — you essentially get more radiation exposure on a trip across the country on an airplane than getting a DEXA scan. But you wouldn't want to do a DEXA frequently.
Whereas we have an easy little step-on scale that has eight points and does your body composition too — that you can do every day if you wanted, not that we'd ever recommend doing it every day. That's by bioelectrical impedance.
Another way to measure muscle mass is functional testing. Grip strength is one of those tests — it's very predictive and closely associated with all-cause mortality; the better your grip strength, the less all-cause mortality you display. A walking test — your walking pace is a very good predictor for longevity. Slower than 0.8 meters per second — anything slower than that lets us know we don't really have a good, solid muscle foundation. Muscle is one part of that, cardiovascular is another. And then there's the sit-to-stand test, a functional strength assessment: in 12 seconds, how many times can you get up and down out of the chair? You should be able to get about five times in 12 seconds — you have to get at least five to have a reasonable functional assessment. It's just a quick little fun trick you can try at home, and something you can trend.
The Hormonal Drivers
The next thing is the hormonal drivers that go along with sarcopenia. Testosterone is a big anabolic signaler for muscle protein and tissue synthesis, and that slowly declines — again, after 30, about 1% a year. As we see those slow declines, we experience muscle tissue wasting. There's been a lot of theory that our testosterone levels 50 or 100 years ago were maybe higher at certain ages. You can presume that, instead of my testosterone level as a man being in the four or 500s now, it used to be six or 700s for a similar age, so that's a consideration.
Estrogen also protects our muscle quality and cellular function, and we all know that drops rapidly in perimenopause. Testosterone declining 1 to 2% per year after 30 is more in the men's realm; women lose all of their hormones probably quicker than that. Other anabolic signaling hormones are growth hormone and insulin-like growth factor — those peak in our 20s and slowly decline from the 30s on. And then cortisol is very catabolic. So you've got testosterone that's anabolic, building up, and cortisol that's catabolic, breaking down — and chronic stress is what we're talking about there; it's an active driver of muscle breakdown.
Something important to think about is that this isn't typically discussed at your annual healthcare visit. It's something you have to be aware of on your own.
Why Muscle Is So Important
So why is muscle so important? It's not just about strength. Muscle has been said recently to be the organ of longevity. As we learn more — and these aren't necessarily things we didn't know before, but we didn't put it together quite like we do today — we're looking at longevity as a whole. Stability and safety are very important. Muscle development and maintenance is a really important part of life, and with our increasing sedentary behaviors, it's not always easy to get the activity we need to stimulate that muscle synthesis.
### Muscle and Blood Sugar Control
The first talking point is the relationship between muscle and blood sugar control. Muscle is a glucose disposal site — you can think of it as the sponge or the garbage disposal. You've got to get glucose into the cell, and muscle accounts for about 80% of that glucose uptake after a meal. When we eat, we get glucose, and that has to be gotten rid of, because as our glucose levels go up, our insulin levels do too, and insulin can be quite inflammatory. Muscle is the primary site, and it does this through a couple of pathways: it absorbs glucose from a non-insulin pathway, and an insulin-dependent pathway — the GLUT4 pathway — which is how glucose gets inside the cell to produce energy. So the more muscle we have, the more capacity we have to dispose of glucose. This is why you hear it's a good idea to take a walk or do some movement after you eat — using those big muscles really helps sponge up that glucose.
When we lose muscle, we also lose insulin sensitivity, so we get insulin resistance. That's another negative feedback loop, because as your insulin resistance gets worse, so does your muscle loss. This is why two people can eat the exact same meal and have completely different blood sugar responses — one has the bigger muscle mass to help control that glucose spike, or has stimulated their muscles to take in that glucose, whereas the other has not.
### Muscle and Resting Metabolic Rate
The next section is how muscle affects your resting metabolic rate — it's a metabolism driver. Each pound of muscle burns about six calories at rest, whereas fat only burns about two. So the more muscle we have, the more calories we burn. You can extrapolate this: if I've lost 10 pounds of muscle over 10 years, I'm now burning about 200 to 250 fewer calories per day at rest. The calories build up because our eating habits stayed the same, but our muscle — our calorie catabolism — hasn't kept up. This is where we hear "I haven't changed anything and I'm gaining weight" — that's a perfect example of how your body composition changing creates those changes.
### Muscle as an Endocrine Organ
Muscle is an endocrine organ too. It releases myokines — basically little signaling proteins, almost like little hormones. They actually help with fat burning and support your bone density. Specifically, irisin will cross the blood-brain barrier and promote brain-derived neurotrophic factor, which helps with neuroplasticity — improving cognition. There's also exercise-induced IL-6, which has an anti-inflammatory effect, improves our insulin sensitivity, and supports our immune system function. Insulin-like growth factor also promotes muscle repair and growth and is very neuroprotective. One thing to note: when you don't have muscle, you're losing that chemical signaling. Those key myokines — that signaling effect comes from utilizing the muscles, and having larger muscles means more myokine release. That's where the benefits of exercise lie. That's where "muscle is medicine" comes in — we're literally synthesizing compounds that reduce our inflammation, protect our brain, and support our metabolism.
### The Muscle-Bone Connection
Next is the muscle-bone connection. We always talk with our patients about building muscle to help build bone. Sarcopenia and osteoporosis can be what we call traveling companions — they share the same hormonal drivers and loading mechanisms. Mechanical movement stresses the bone; the bone is constantly being produced, remodeled, and broken down, and healthy bone is there because of healthy muscle. The key clinical consequence is that your fracture risk rises when your muscle and bone are compromised. So stronger muscle leads to stronger bones and more stability and safety.
### The Muscle-Brain Connection
The muscle-brain connection is also a big one. That brain-derived neurotrophic factor is the primary growth factor for neurons — the cognition part of this, the neuroplasticity. We talked about this in a previous podcast on brain health and it being a lifestyle disease, and muscle is a big component of that. That exercise-induced myokine, irisin, crosses the blood-brain barrier and reduces nerve inflammation, helping combat the cognitive decline we sometimes see.
### The Longevity Connection
Now the longevity connection — how grip strength and gait speed tell us about our longevity outlook. They're very strong predictors of all-cause mortality; the research is extensive, and in some situations they can be a better predictor than even blood pressure. Gait speed is a good predictor of how good our longevity is going to be — it can even predict that folks may have more hospitalizations, issues, and fractures. It's also an indicator of how well you're going to recover, say from a severe illness or injury, when you have more muscle reserve. So sit and think about this: what's a better predictor — my cholesterol or my grip strength? The importance of muscle is a long-term survival issue.
### The Gender Lens
Then there's the gender lens. Women start with 30 to 35% less muscle mass than men and lose it faster because of perimenopause and the loss of estrogen and testosterone. Women definitely bear the disproportionate burden here, with higher rates of frailty, falls, fractures, and nursing home admissions. Men have the testosterone levels to support us, which gives us an advantage until we get through andropause; then it starts to decelerate, and we have more vascular complications compounding the picture after that. But really, both men and women aren't being screened or treated for sarcopenia.
The Drivers of Sarcopenia
What are the drivers — and what can we do to support our system physiologically to make muscle?
Right off the bat: protein. The RDA is only a recommendation of 36 grams — not even half a gram per pound of ideal body weight. That's the old one, I think. At any rate, it's underdosed; it's just not enough to preserve muscle. We typically request that folks get at least a gram per pound of ideal body weight per day of protein. And let's say, "I didn't eat much protein today, but tomorrow I'll make up for it." You cannot make up for it — if you don't meet the goal, you lose. It's not something you can regenerate; that's gone. So maintaining protein intake is the key to maintaining muscle synthesis. People trying to watch their calories may focus on other things instead of protein, and a lot of times, if you haven't thought about protein, it's highly likely you're not getting enough. It's hard to get the amount of protein to build and maintain muscle, but once you get used to it, it becomes a lot easier, and you find you're more satiated with the higher amounts — good quality calories instead of empty calories.
In midlife, it gets harder for us to make muscle — that's called anabolic resistance. You don't have to worry about it so much in your 20s, but you do in your 50s and 60s.
The second driver is physical inactivity or undertraining. Our lives today are much more sedentary than even 20 years ago; technology has helped do that — it's a lot easier to work from our chair than to get up and move. You can call it disuse atrophy — you don't use it, you lose it. We see this in injury and illness too, when people are in the hospital and can't get up and move around. I can't remember the exact statistic, but every day you're in bed with an illness or injury is like so many days of rehab to get you back — I'll have to look it up, but it's a real thing.
The next driver is chronic inflammation. There's a lot that creates chronic inflammation in our lives — pro-inflammatory cytokines that directly suppress protein synthesis and promote muscle breakdown. And ultra-processed foods, high visceral fat levels, poor sleep, and a lot of chronic stress all play into that.
Then there's hormone decline — another key driver. We really need to support estrogen, testosterone, and growth hormone production; they're anabolic signalers, so if we're not supporting our hormone levels, we have trouble with muscle production. This is where there's often a big misconception of hormone replacement therapy being more for libido and things like that — but the truth is, muscle is a big part of it.
And chronic stress and cortisol. Cortisol is catabolic, so it tends to break down muscle chronically. We're not talking about acute stress — acute stress is good for our system — but chronic cortisol elevations tend to break down muscle. This is why stress management is so important and very underutilized. A lot of folks manage stress and say, "Well, I'm not stressed," but in reality you are stressed — you do a good job managing it, but it's still there under the surface.
The sixth driver is poor sleep. Sleep is when our body recovers, and when we're not getting adequate sleep, our growth hormone is less. Growth hormone is the primary overnight muscle repair signal, and 80% of it is released during sleep — that's why everybody stresses good quality sleep. Sleep apnea is a classic example: folks with pauses in their breathing never get to the deeper layers of sleep to reach adequate growth hormone levels. It's an underdiagnosed midlife problem.
So what we've just described — undereating protein, not lifting, living with inflammation, hormones declining, cortisol elevated, poor sleep — for a lot of midlife adults, that's not an exaggeration; that's like a Tuesday. Every one of those forces works against our muscles simultaneously, and that's why it's so hard to turn it around.
How to Reverse Sarcopenia
There's a lot you can do — you've got a lot of power. First, going through our Reveal, Rebalance, Revive framework: you have to know where you are to know what to work on.
### Reveal
That's where the body scans come in. Bioelectrical impedance testing scales are quite affordable — not that expensive. DEXA scans are also pretty inexpensive; they're usually self-pay, out of pocket, but I think we're able to get those for around $75 in our local self-pay radiology imaging department. It's not just BMI — BMI is old school and inaccurate. Someone could be 6'5" and classified as obese but be a linebacker — it's just not accurate. That's why body composition is important. A good muscle-to-fat ratio — body fat percentage for a man is 14 to 24%, and for a female 21 to 31%. A healthy lean body mass for a man is around 80%, and for a woman around 70%. If somebody is particular about their activities, how they eat, doing the right things, and optimizing their hormones, they can achieve those levels for optimal health. And every body is different — even if you're not at those generalized numbers, knowing what your numbers are can help you know if what you're doing is helping. It's all about the trend: is it getting better or worse, am I improving my muscle content and reducing my body fat?
Grip strength — we didn't specify how you test it. There are machines you can use, and there's also a dead hang: how long can you hang? That helps you know where you're at, and then you watch how it trends when you repeat the test. An optimal dead hang time for a male should be around two minutes, and for a female a minute and a half. If you can't hang that long, it's a goal — but it's not easy, and that's just hanging there, holding onto a bar.
Lab panels are another way we reveal. We're going to look at the insulin level, HOMA-IR (which tells us how insulin resistant a person may be), your hormones, thyroid, vitamin D, and C-reactive protein — some really good foundational labs to see where you're at. And before you know what to do about protein, you have to know how much protein you're getting today. If your current number is 60 grams of protein — not uncommon for people who aren't paying attention — we're not going to say, "Tomorrow get twice that, 130 grams a day." That's not going to happen. So track your food for three days to get an idea of where your protein is. It doesn't mean you have to track it every day the rest of your life — just get an idea: this is how much chicken, beef, or fish, and how much protein I need, and where I need to improve.
And sleep quality. You don't have to monitor your sleep — it can be nice, but it can also be detrimental; some people get discouraged when their sleep score doesn't match how they thought they slept. Some things to pay attention to: are you dreaming? That helps you know if you're getting good quality sleep. And how do you feel in the morning — do you feel rested? Also, talk with your sleep partner about whether you're snoring or pausing your breath when you sleep. And if you're not sure, there are sleep studies, and apps on your phone that will listen while you sleep at zero cost.
### Rebalance
Some of the non-negotiables for rebalancing: fixing the protein — like we said, target 0.8 to one gram per pound of ideal body weight, not necessarily your current weight. A good gauge is 30 to 40 grams per meal. If you're only eating two meals a day, which some people are, make note of that — there have got to be some other sources, whether bars, drinks, or shakes, to get that protein in. We'll dive deeper into this on our next podcast.
The second non-negotiable is resistance training — it's got to be in there somewhere, and that's for females too. The old adage is that the girls do the treadmills and the stairsteppers and the guys lift the weights — we need to change that around. I actually saw the other day that Planet Fitness is changing their gyms because so many women are lifting weights now. That's awesome. Resistance training is the way to do it, and you really need to push the heavy weights — it's not about just picking up a two- or three-pound weight. You're trying to stimulate the muscles, getting those type 2 muscle fibers, and stimulate bone growth; that's what leads to anabolic muscle synthesis. And I'll reiterate — I feel like I say this almost every podcast — if you're starting from zero, start slow and increase. We don't want to injure ourselves. Definitely work with a trainer if you can. The key is being consistent, doing something you can do consistently. Not everybody enjoys the same exercise — some don't like running, some don't like lifting — so find a mode of activity you enjoy and have fun doing, maybe being outdoors versus inside a gym.
The third non-negotiable is to address your hormones and your sleep. We say it all the time: you cannot out-train or out-eat a hormonal deficit. If your hormone levels — testosterone, estrogen, thyroid — aren't optimal, the muscles will not respond the way they should. It's pretty classic and obvious when it happens: somebody who's worked out their whole life reaches a point where they just can't seem to get anywhere or get stronger — that's where those individuals may simply have imbalanced hormones.
### Revive
What can we do to revive ourselves? Creatine is a really great thing when it comes to muscle and brain — five to 10 grams. We always say five grams goes to the muscle, and the amount over five grams can go to the brain. That's very generalized, but there are plenty of studies supporting the benefits of supplementing creatine.
Track your body composition. A lot of gyms now have a body composition test you can use — I know GNC has InBody — they're not as inaccessible as they used to be. Track it, because that's how you'll know if what you're doing is working. And have a team: work with a provider who will help you optimize your hormones, a trainer who will help you with proper techniques, and a nutritionist who can help with fueling. It's not something you do on your own; it's better served to have a team on your side.
That pretty much wraps up sarcopenia for today. We'll be looking forward to putting together an interview with a trainer to talk about the actual protocols for strength training and nutrition. It's important to identify the problems and know nutritionally and hormonally what you need to do, but also physically — ways to do things that are safe and productive. If you're going to put forth the effort, you want to make sure your gains are noticed. Thanks for joining us today, and reach out with any questions. Have a healthy day.