Understanding Aging: How Cellular Health and Metabolic Function Shape Longevity

Welcome back to The Young Lab, the podcast where internal health, performance, and regenerative aesthetics converge within an evidence-backed framework. In this episode, host Dr. Young dives beneath the surface of aging and chronic disease, challenging the common notion that these are just inevitable parts of getting older.

He uncovers what’s actually happening in our cells as we age, exploring the science behind the hallmarks of aging, the biological cascade leading to chronic illness, and the central role of metabolic health and inflammation. You’ll discover why issues like heart disease, diabetes, and cognitive decline are decades in the making, and how cutting-edge therapies like peptides and regenerative medicine fit into the bigger picture of longevity science. Most importantly, Dr. Young shares why focusing on cellular repair, mitochondrial function, muscle mass, and the fundamentals of healthy living are still the most powerful ways to influence how well and how long you live.

Get ready for an enlightening look at how understanding the biology of aging can help you take control of your health, prevent chronic diseases, and maximize your healthspan. If you’re interested in living longer, stronger, and healthier, you won’t want to miss this episode!

Timestamps:

00:00 "Cellular Aging: Beneath the Surface"

05:35 Cellular Cleanup and Aging

07:57 "12 Hallmarks of Aging"

12:34 "12 Hallmarks of Aging Explained"

16:47 Chronic Disease Starts Early

19:52 "Metabolic Health Crisis in America"

21:15 "Preventing Disease Through Early Interventions"

27:14 Inflammation: Protector Turned Persistent

29:02 Zombie Cells Drive Chronic Inflammation

34:08 "Mitochondria: Ancient Symbiotic Bacteria"

35:12 Mitochondria: Maternal Energy Legacy

39:26 "VO2 Max and Longevity"

41:54 "VO2 Max and Longevity"

46:24 "Measuring Resilience for Longevity"

51:21 Regenerative Medicine Advancements

53:37 "Longevity Foundations and Advanced Tools"

Show Website - https://theyounglab.com/

Dr. Michael Young's Clinic - http://denverwellnessaesthetic.com/

Dr. Young's Instagram - https://www.instagram.com/michael.youngmd/

Media Partner - https://www.tophealth.care/

“Disclaimer: Informational only. Not medical advice. Consult your doctor for guidance.”

Transcript

SPEAKER_02 0:00

Large national studies have shown that only about 12% of American adults are considered metabolically healthy, meaning nearly nine out of 10 people have some degree of metabolic dysfunction. What we typically see clinically, a heart attack or diabetes diagnosis or cognitive decline, is usually the final stage of a biological process that has been developing quietly for decades. The biology that determines how long we live is deeply connected to the biology that determines how well our bodies function every day.

SPEAKER_00 1:08

Because one of the most powerful things people can understand is how disease actually develops in the body. So, Dr. Young, it's always a pleasure to see you. Are you ready to dive into this episode?

SPEAKER_02 1:17

Yeah, let's get started. I'm excited.

SPEAKER_00 1:19

Awesome. And this is a great question that I'm like excited to ask and learn about. So I know when people hear the word aging, we all tend to really think about wrinkles or gray hair. But biologically aging is something actually very different. So, from your standpoint and a physiological standpoint, what is actually happening inside the body as we age?

SPEAKER_02 1:40

When most people think about aging, they picture things like you mentioned, like wrinkles or gray hair. And these are changes that are real, but they're actually surface reflections of a deeper biological process that's happening within ourselves. So for example, wrinkles develop partly because collagen and elastin, which are the structural proteins that support our skin, become damaged over time and are replaced less efficiently. Gray hair happens when the pigment-producing cells of our hair follicles gradually lose the ability to produce melanin. So those outward changes are real, but they're really just visible signs of cellular aging happening throughout the body. At its core, aging is about how well our cells maintain and repair themselves over time. Every second of our lives, trillions of cells are performing maintenance. They're repairing DNA, they're replacing damaged proteins, they're generating energy, and they're clearing out cellular debris. So when you're young, these systems and the repair systems work remarkably well. But as we age, something important begins to happen. The balance between the damage and the repair systems slowly shift. Damage begins to accumulate a little faster than the body can repair it. And that gradual accumulation of damage is really what we recognize as biological aging. One place that this happens is in our DNA. Our DNA is constantly being damaged by just normal metabolism, and there are things like environmental exposures, such as ultraviolet light, toxins, and even by the process our cells use to generate energy. So scientists estimate that tens of thousands of DNA damage events occur in each cell every day. But fortunately, cells have sophisticated repair systems. They're specialized enzymes that constantly scan our DNA looking for errors and repair them through multiple pathways designed to maintain genetic stability. But as we age, those repair systems become less efficient and small errors begin to accumulate over time. Another important process involves proteins. Proteins do most of their work inside our cells. They function as enzymes, structural components, signaling molecules, and transport systems. But proteins can become damaged through normal metabolism, oxidation, and other stressors. Cells normally identify those damaged proteins and break them down through a quality control system so they can be replaced with new ones. So when these systems slow down, damaged protein begins to accumulate and they start interfering with normal cellular function. Another major part of the story involves mitochondria, which we have described before and people mostly know as the power plants or the powerhouse of the cell. So mitochondria generate energy through a process called oxidative phosphorylation. They take nutrients from food and combine them with oxygen to produce ATP or adenosin triphosphate, which is essentially the energy currency of the body. Truly, we are just batteries. Every cell, every function requires ATP, I meant muscle contraction, brain fog, immune activity, cellular repair, but mitochondria themselves are also vulnerable to damage. Over time, they can accumulate damage to their membranes and their own mitochondrial DNA, which reduces their ability to produce energy efficiently. So when cellular energy production declines, many of the repair systems inside the cell begin to struggle. Another essential protective system is autophagy. Autophagy literally means self-eating. It is the process cells use to identify and remove damaged components, things like defective proteins and worn-out mitochondria and other cellular debris. So you can think of autophagy as the cell's cleanup and recycling system. When autophagy works well, cells remain healthy and efficient because damaged structures are constantly removed and replaced. But when autophagy slows down, those damaged components begin to accumulate inside the cell. And that accumulation creates additional stress that disrupts energy production, signaling, and repair. So when we take a step back and look at the bigger picture, aging is really the gradual accumulation of cellular damage across multiple systems. You have DNA damage, you have protein damage, you have mitochondrial damage, and reduce cellular cleanup through autophagy. Individually, these changes are small, but over decades they compound. Cells lose efficiency, tissues lose resilience, and eventually those biological stressors begin to show up as chronic diseases we see later in life, and those things like cardiovascular disease, diabetes, neurodegenerative disease, and frailty. So, biologically speaking, aging isn't just the passage of time. It is the gradual shift in the balance between cellular damage and the body's ability to repair itself. And one of the most encouraging things about longevity science is that many of the things we talk about, exercise, nutrition, metabolic health, sleep, and even certain therapies, actually help support these repair systems and slow the accumulation of damage.

SPEAKER_00 7:38

In longevity science, researchers often talk about the hallmarks of aging, which I think is something a lot of people have heard that phrase or that quote, but may not really understand it. So, or maybe people haven't heard it. So for someone hearing that phrase for the first time, what does it really mean? And why do you think it is such an important framework?

SPEAKER_02 7:57

So once we understand that aging involves the gradual accumulation of cellular damage, the next logical question becomes what types of biological damage are actually driving that process? And that's where the concept of hallmarks of aging come in. In longevity science, researchers have identified a set of core biological processes that appear to drive aging across many different tissues and organs. Originally there were nine hallmarks described, but as our understanding of aging biology has expanded, the framework now includes 12 hallmarks of aging. These represent the major biological mechanisms that gradually reduce the body's resilience over time. So let me briefly walk through them and try to provide them in simplistic terms or simple terms. Genetic instability is the first one. And this refers to the accumulation of damage in our DNA over time. DNA is constantly being exposed to metabolic stressors and environmental factors. And when that damage isn't repaired properly, it can disrupt how the cells function. So number two would be telomere shortening. This involves the gradual erosion of the protective caps at the end of our chromosomes. We kind of think of them like the plastic tip on the end of our shoelaces. So every time a cell divides, these caps shorten slightly, and eventually cells lose their ability to divide and repair tissues. Third would be epigenetic alterations, and this refers to the changes in how genes are regulated. Our DNA sequence may remain the same, but the way genes are turned on or turned off can shift over time, changing how the cell behaves. Number four would be a loss of proteostasis, and this involves problems with proteins maintaining their proper structure. Proteins must fold into extremely precise three-dimensional shapes in order to function correctly. If their structure changes even slightly, the protein may no longer work properly. Over time, damage or misfolded proteins can accumulate and disrupt cellular processes. In neurodegenerative diseases like Alzheimer's, for example, we actually see large accumulations of abnormal proteins in the brain. The next would be, and that's number five, would be dysregulated nutrient sensing. So our cells constantly monitor energy and nutrient availability and adjust their behavior accordingly. Two important signaling pathways involved in this process are mTOR and AMP kinase. So you can think of mTOR as a growth signal. So when nutrients are abundant, mTOR tends to tell cells to focus on growth and building new proteins and cellular structures. In contrast, AMP kinase acts as an energy sensor. So when energy is low, such as during exercise or fasting, AMP kinase signals to the cell to conserve energy and improve metabolic efficiency and then activate a repair process like autophagy. So in healthy physiology, these pathways stay in balance, but when nutrient signaling becomes chronically dysregulated, the body may spend too much time in growth mode and not enough time in repair and maintenance. So over time, that imbalance contributes to aging and metabolic disease. Number six would be mitochondrial dysfunction. This is another major hallmark. Mitochondria generate ATP, which we've already mentioned. ATP is our energy currency that powers every cellular process. Things such as DNA repair requires energy. Protein maintenance requires energy. Immune regulation requires energy. So when mitochondrial function declines, the entire cellular system begins to struggle. Number seven would be cellular senescence. Sometimes when cells become damaged or stress, they stop dividing, but they don't die. Instead, they remain in tissues in a dysfunctional state. And we've often referred to these as zombie cells. They're alive, but they no longer function properly. Even more importantly, senescent cells begin releasing inflammatory signaling molecules that can disrupt the function of surrounding healthy cells. So as these zombie-like cells accumulate over time, they contribute to chronic inflammation and tissue dysregulation and many of our age-related diseases. Number eight out of the 12 would be stem cell exhaustion. And this refers to the gradual decline in the number and the function of stem cells that normally repair and regenerate tissues throughout the body. Number nine would be altered intercellular communication. And this means that the signaling between cells becomes dysregulated, which can impair coordination across tissues and organs. So more recently, researchers have emphasized three additional hallmarks to make the 12. Number 10 would be chronic inflammation, or sometimes called inflammaging. And this refers to a persistent low-grade immune activation that develops with age and contributes to many of the chronic diseases. Number 11 would be disabled macroatophagy. And this involves the impairment of the cell's cleanup systems and recycling system. Atophagy normally removes damaged proteins and organelles, but when the system slows down, cellular debris accumulates. And number 12 would be dysbiosis. And this refers to the disruption in the microbiome. The microbiome is the trillions of microorganisms living in our gut that influence metabolism, immunity, and inflammation. Now, I know that sounds like a lot, that's a pretty long list, but the important thing to understand is that these processes don't occur independently. They interact and amplify one another. Among them, mitochondrial function sits very close to the center of the system because energy production is required for nearly every cellular response or process in the body. When mitochondrial function declines, DNA repair becomes less efficient, protein maintenance becomes more difficult, autophagy slows down, and inflammation tends to increase. One helpful way to think about this is as an aging cascade. It often begins with metabolic stress, things like poor metabolic health, excess caloric intake, physical inactivity or stress or chronic stress. So over time, that metabolic stress places strain on mitochondria, which reduces energy production and increases oxidative stress. That oxidative stress damages DNA, proteins, and cellular membranes. The immune system begins responding to those damage signals and chronic low-grade inflammation develops. Cells begin entering senescence, stem cells lose regenerative capacity, and cellular repair systems begin to become less efficient. So eventually, as this biological cascade progresses over decades, we begin to see that clinical diseases that people recognize later in life, such as cardiovascular disease and metabolic disease, neurodegenerative disease, and frailty. So what we often call chronic disease is really the result of these aging processes accumulating over many years. And the reason this framework is so powerful is that it changes how we think about medicine. Instead of treating heart disease, diabetes, dementia, and cancer as completely separate problems, we start recognizing that many of these conditions share the same underlying biological drivers. And when we improve mitochondrial health, metabolic function, inflammation, muscle mass, and cellular repair systems, we're not just targeting one disease. We're improving the biology of aging itself.

SPEAKER_00 16:22

With chronic disease, I know you kind of mentioned this earlier, but it seems like chronic disease develops over time. So I know most people think diabetes or diseases like diabetes, for example, heart disease or dementia suddenly appear later in life. But in reality, those processes often build up over time, decades even earlier. So how does chronic disease actually develop over time?

SPEAKER_02 16:47

One of the most important things for people to understand about chronic disease is that it almost never develops suddenly. What we typically see clinically, a heart attack or a diabetes diagnosis or cognitive decline, is usually the final stage of a biological process that has been developing quietly for decades. In medicine, we often diagnose disease when symptoms appear or when lab values cross a certain threshold. But the biology that leads to those diseases usually begins 20 or even 30 years earlier. A good example of this is atherosclerosis, and this is a process that typically leads to heart attacks and strokes. For many years, people assumed plaque buildup in arteries started later in adulthood. But autopsy studies of young adults who died in accidents, particularly the P-Day study, which looked at the arteries of people between the ages of 15 and 34, showed something surprising. Researchers found early atherosclerotic lesions in nearly half of the individuals in their 20s. That means that the process that eventually leads to cardiovascular disease can actually begin early in life. And the same pattern exists for metabolic disease. One of the central drivers of metabolic disease is insulin resistance. And insulin resistance usually develops long before someone is diagnosed with diabetes. In fact, research suggests insulin resistance may begin 10 to 20 years before diabetes is diagnosed, while the stage we call prediabetes often develops five to 10 years before the diagnosis. So during this time, the body compensates. The pancreas produces more insulin to keep blood sugars in normal range. So a person's glucose levels may still look normal on a routine lab draw or lab work, but metabolically the system is already under significant stress. Eventually, the pancreas can't keep up with the demand. Blood sugars begin to rise, and that's when the disease becomes clinically visible. But by that point, the biological process has usually been developing for many years. What's even more concerning is that we're seeing many of these disease processes appear earlier in life than they did in previous generations. So childhood obesity has more than tripled since the 1970s. Roughly 20% of adolescents in the United States are now obese, and about one in five teenagers have prediabetes. Type 2 diabetes, which used to be called adult onset diabetes, is now regularly diagnosed in teenagers and even children. And when diabetes develops in youth, it tends to progress more aggressively, leading to earlier complications. These trends reflect a broader problem with metabolic health. Large national studies have shown that only about 12% of American adults are considered metabolically healthy, meaning nearly nine out of 10 people have some degree of metabolic dysfunction, which means the vast majority of people show some degree of metabolic dysfunction even if they haven't been diagnosed with a disease. While researchers talk about being metabolically unhealthy, they are usually referring to abnormalities in key systems that regulate energy and metabolism. These include things like elevated blood pressure, impaired glucose regulation, high triglycerides, low HDL cholesterol, and increased abdominal or visceral fat. These markers reflect problems with how the body processes and stores energy. And over time, the metabolic dysfunction contributes to insulin resistance, chronic inflammation, vascular damage, and mitochondrial stress, which are major drivers of chronic diseases. So when we step back and look at the big picture, what we often call chronic disease is really the end result of a lung biological cascade. It often begins with metabolic stress. That metabolic stress affects mitochondria and energy production. Oxidative stress increases, inflammation begins to rise, cells enter senescence, repair systems weaken, and over time the tissues lose their ability to maintain normal function. Eventually, after decades of biological stress, the system reaches a threshold where disease becomes clinically apparent. So what we recognize as heart disease, diabetes, or neurodegenerative disease is often the late stage expression of biological processes that started much earlier in life. And that is why the conversation around prevention is so important. If we wait until disease appears, we're often intervening. Very late in that biological timeline. But if we identify metabolic dysfunction early and support things like mitochondrial health, muscle mass, metabolic flexibility, and inflammation control, we can often slow or interrupt that cascade long before disease develops. And that's one of the most important shifts happening in modern longevity medicine. Instead of waiting for disease to appear and reacting to it, we're beginning to focus on understanding and modifying the biology that leads to disease in the first place.

SPEAKER_00 22:37

Absolutely. And when you look at the major diseases that shorten health span, like cardiovascular disease, diabetes, like you mentioned, obesity, even some neurodegenerative conditions, metabolic dysfunction really seems to sit at the center. So why is it so critical to longevity?

SPEAKER_02 22:54

Metabolism is really the foundation of how the body produces and uses energy. Every cell in our body requires energy to function properly. I mean, we we need energy to repair DNA and to maintain and make proteins, regulate inflammation, support immune function, and just pretty much maintain normal cellular signaling. That energy ultimately comes from how our bodies process nutrients like carbohydrates, fats, and proteins. When metabolic systems are functioning well, the body can't efficiently convert nutrients into energy and shift between different fuel sources depending on what the body needs. This ability to shift is called metabolic flexibility. So, for example, after we eat, the body can use glucose from carbohydrates as a fuel source. But when we're fasting, sleeping, or exercising, the body should be able to shift toward burning fat for energy. A healthy metabolism moves smoothly between these fuel sources depending on the situation. But when metabolic health begins to decline, that flexibility is lost. One of the earliest signs of metabolic dysfunction is insulin resistance. Insulin is the hormone that allows glucose to move from the bloodstream into cells so it can be used for energy. When cells become resistant to insulin, the body compensates by producing more of it. So for a period of time, that compensation keeps blood sugar levels normal. But insulin levels remain elevated, and that creates several downstream problems. Fat burning becomes suppressed, fat storage increases, inflammatory signaling rises, and mitochondrial stress increases. Over time, this can contribute to visceral fat accumulation, chronic inflammation, and many of the biologic processes we've talked about earlier with the hallmarks of aging. Another concept that's important here is fuel dependence. Carbohydrates themselves are not inherently bad. Many healthy populations consume high amounts of carbohydrates. The real problem occurs when the body becomes metabolically inflexible and dependent on glucose for energy. In that situation, the body struggles to excess stored fat for fuel. Energy levels become unstable, blood sugar spikes after meals and drops between meals, and insulin levels remain elevated more than they should. A healthy metabolism should be able to switch between burning glucose and burning fat depending on the body's needs. When that flexibility is lost, the metabolic system becomes much more fragile. Research shows that about 70 to 80% of Americans show some evidence of insulin resistance, even if their glucose levels are still normal. And this issue is far more common than most people realize. Another important factor in metabolic health is skeletal muscle. Muscle is one of the body's largest metabolic organs. It stores glucose, it helps regulate insulin sensitivity, and it plays a major role in maintaining metabolic flexibility. So when muscle mass declines, which happens with aging or physical inactivity, the body's ability to regulate glucose and maintain metabolic health declines as well. So when we step back and look at the big picture, metabolism isn't just about weight. It's really about how efficient the body manages energy, regulates nutrients, and maintains cellular repair systems. So when metabolism is healthy, many of the hallmarks are aging or slowed. But when metabolism becomes dysfunctional, many of these processes accelerate. And that's why improving metabolic health through nutrition, physical activity, muscle preservation, sleep, and metabolic flexibility becomes one of the most powerful levers we have for improving health span.

SPEAKER_00 27:04

And another term that we hear frequently is chronic inflammation. So why does inflammation become such a powerful driver of aging and disease?

SPEAKER_02 27:14

So inflammation is actually a very important, necessary part of human biology. When we get injured or develop an infection, the immune system activates an inflammatory response to help eliminate pathogens, remove damaged tissue, and begin the healing process. In that situation, inflammation is protective, but it's temporary. The problem occurs when inflammation becomes chronic and persistent. Instead of turning on and off when needed, the immune system begins to remain in a low-grade activated state for long periods of time. In longevity science, this phenomenon is often referred to as inflammaging, a combination of inflammation and aging. One helpful way to think about inflammation is that it acts as a kind of molecular sensing system. Our immune systems are constantly monitoring the body for signals that something is wrong. These signals can come from infections or from injuries or from damaged cells. At the molecular level, cells release what's called damage-associated molecular patterns, sometimes referred to as just danger signals. These molecules tell the immune system that cellular stress or damage is occurring. When this happens, the immune system activates inflammatory pathways to respond. So the system is incredibly important for survival. But as we age and as metabolic stressors accumulate, the body begins to generate more of these damage signals. Mitochondrial dysfunction increases oxidative stress, damaged proteins accumulate, cells enter senescence, sometimes, as we stated earlier, called zombie cells. These zombie cells release inflammatory signals. And metabolic dysfunction alters signals throughout the tissue. All of these processes produce signals that the immune system interprets as danger. So inflammation becomes chronically activated. And chronic inflammation can affect almost every system in the body. In the blood vessels, inflammation contributes to the development of atherosclerosis, as we mentioned earlier, that this is the plaque buildup that leads to heart attacks and strokes. In metabolic tissues like liver and muscle, inflammation interferes with insulin signaling, worsening insulin resistance. In the brain, inflammatory processes are increasingly linked to neurodegenerative diseases like Alzheimer's or Parkinson's. So inflammation rarely causes just one disease. It acts like a multiplier of risk across many biological systems. Another important driver of inflammation is metabolic dysfunction. When fat tissue expands, particularly visceral fat around the abdominal area, it begins releasing inflammatory signaling molecules called cytokines. These molecules circulate throughout the body and influence immune signaling across many tissues. Another example of chronic inflammation that many people experience is fatigue. So when the immune system becomes activated, it requires a significant amount of energy. Immune cells begin producing inflammatory cytokines that signal the body to redirect resources toward immune defense. These signals also affect the brain and metabolism. In fact, during infection or illness, the body often enters what researchers call sickness behavior. This response encourages rest, reduces activity, and redirects energy toward fighting infection. It's actually an evolutionary survival mechanism. But when inflammation becomes chronic, those signals can persist even when you're not sick. Inflammatory cytokines can interfere with mitochondrial energy production, alter brain signaling, and reduce metabolic efficiency. As a result, people may experience persistent fatigue, brain fog, reduced motivation, and decreased physical endurance. So fatigue isn't always simply about sleep arrest. Sometimes it reflects underlying inflammatory and metabolic stress within the body. Over time, this chronic inflammatory environment accelerates several of the hallmarks of aging. DNA damage increases, mitochondrial function declines, and cells enter senescence, and cellular repair systems become less efficient. So inflammation becomes both a result of aging biology and a driver of further damage. And this is why many of the interventions we talk about in longevity medicine, once again, exercise, metabolic health, sleep, nutrition, and maintaining muscle mass have such powerful effects. They can help reduce the biological stressors that trigger chronic inflammation in the first place. When we improve metabolic health and support cellular repair systems, inflammation often improves as well. So inflammation isn't just a symptom of disease, it's one of the central biological processes linking aging to many of the chronic diseases we see later in life.

SPEAKER_00 32:52

And I think one of the most fascinating areas in longevity science is mitochondrial health. So why do these tiny energy-producing structures have such an enormous impact on, like you talked about fatigue and aging and diseases?

SPEAKER_02 33:08

So, yeah, mitochondria are these tiny structures that exist inside almost every cell in the body. So their primary job is to produce energy. Specifically, mitochondria convert nutrients and oxygen into a molecule called ATP, which, you know, ATP, as we discussed earlier, is our true energy currency that powers every cellular activity. And every biological process in the body requires energy. As we stated earlier, muscle contraction requires energy, brain signaling requires energy, DNA repair requires energy, protein maintenance and formation require energy. Even our immune systems, as we stated previously, require large amounts of energy to function properly. So mitochondria are not just important for athletic performance or endurance. They are fundamental to every biological process that keeps cells functioning properly. So one of the most fascinating things about mitochondria is their evolutionary history. So scientists believe that bacteria entered into a symbiotic relationship with early cells more than a billion years ago. These ancient bacteria were very efficient at producing energy using oxygen. Over time, they became integrated into our cells and evolved into what we now know as mitochondria. So really, mitochondria are just bacteria that have evolved to actually coexist or once again evolved into a symbiotic relationship, which means that we both, the mitochondria and our cells, or benefit would benefit from this relationship. Although they have become part of our cells, they still retain some characteristics of their bacterial ancestry. For example, mitochondria have their own DNA, and that's separate from the DNA that is in the nucleus in our cells. This mitochondrial DNA contains genes involved in energy production. And another interesting feature is that mitochondrial DNA is inherited almost exclusively from our mothers. During fertilization, the mitochondria present in the egg and become the mitochondria that populate the cells of the developing embryo. So, in many ways, our mitochondrial lineage is passed down through the maternal line across generations. The way mitochondria generate energy is through a process called oxidative phosphorylation. Nutrients like glucose and fatty acids are broken down into smaller molecules that can enter the mitochondria, where electrons move through a series of protein complexes known as the electron transport chain. So as these electrons move through the chain, they create a gradient across the mitochondrial membrane that ultimately drives the production of ATP, kind of like how a battery works. But energy production also produces small amounts of reactive oxygen species, or ROS for short. And these are really reactive molecules. In normal amounts, these molecules actually serve an important signaling function. However, when mitochondria function becomes impaired or when the metabolic stress becomes excessive, reactive oxygen species, or the ROS, can accumulate and begin damaging cellular structures. This damage can affect DNA, proteins, and cell membranes. So over time, this contributes to many of the hallmarks of aging we discussed earlier, including inflammation, cellular senescence, and impaired repair systems. Another important concept is that mitochondria are not static. They are dynamic structures that constantly adapt to the body's energy demands. Cells can increase the number and efficiency of mitochondria when energy demands rise or increase. This process is called mitochondrial biogenesis. This essentially means creating new mitochondria. So one of the key molecular regulators of mitochondrial biogenesis is a signaling protein called PGC one alpha, or peroxone proliferator activated receptor gamma coactivator one alpha. I know that's a lot, but we'll just call it PGC one alpha for short. And this is a master switch that tells the cell to produce more mitochondria and improve mitochondrial efficiency. So several biological processes can signal or activate PGC1 alpha. And one of the most important is that AMP kinase. And remember, AMP kinase acts as a cellular energy sensor. So when cells detect that energy levels are low, like during exercise or during periods of caloric restriction, AMP kinase becomes activated. AMP kinase then signals pathways that increase mitochondrial production and improve metabolic efficiency. Another important regulator is CERT1. This is a longevity associated enzyme that helps coordinate cellular responses to energy states and stressors and supports mitochondrial function. These signaling pathways allow cells to sense energy demand and respond to strengthening the body's energy-producing machinery. And this is one of the reasons exercise is such a powerful longevity intervention. So when we exercise, muscle cells consume large amounts of ATP. That temporary drop in cellular energy activates that AMP kinase and PGC1 alpha. Over time, this stimulates that mitochondrial biogenesis or the mitochondrial creation and also increase in efficiency of the mitochondria. So the body builds more mitochondria. It becomes more efficient at using macronutrients such as the proteins, the fats, and carbohydrates into converting those into ATP. And this mitochondrial biogenesis is one of the main reasons that cardio fitness, often measured as VO2 max, is one of the strongest predictors of longevity. So higher VO2 max levels reflect stronger cardiovascular systems, greater mitochondria density, and a higher capacity for energy production. And kind of going back, VO2 max is just the amount of oxygen needed, the maximum amount that we can use to convert those macros, particularly at this point, carbohydrates, into that energy source, ATP. Higher VO2 max levels reflect stronger cardiovascular systems, greater mitochondrial density, and a higher capacity for energy production. In fact, the human body contains an extraordinary number of mitochondria. Estimates suggest that we have tens of millions of billions of mitochondria. And in tissues with high energy demand, such as the muscle or the brain or the heart, a single cell can contain thousands of mitochondria. This makes sense when you consider how much energy the body requires. For example, the human brain, which represents only 2% of our body weight, it consumes roughly 20% of our body's total energy. All of that energy ultimately depends on mitochondrial function. So mitochondria are not just the energy engines of the cell. They're really one of the central regulators of metabolic health, resilience, and the aging process itself. And the encouraging part is that mitochondria responds strongly to lifestyle factors, to exercise, metabolic health, sleep, nutrition, and maintaining skeletal muscle. All of these interventions stimulate mitochondrial repair and regeneration. So when we talk about improving health span, we are often talking about improving mitochondrial function and cellular energy production.

SPEAKER_00 41:44

And when you do evaluate a patient from a longevity perspective, what metrics actually matter most and what numbers tell you the most about someone's future health?

SPEAKER_02 41:54

That's a great question because one of the most important shifts happening in modern medicine is that we're moving away from the simple diagnosing disease and we're moving toward measuring the biological systems that determine long-term health. So traditional medicine often identifies disease once it's already happened. But longevity medicine focuses on identifying physiological signals that predict future health decades before disease appears. And there are several metrics that consistently stand out in the research. One of the strongest predictors of longevity is cardiorespiratory fitness, which we've we mentioned earlier, is commonly measured as VO2MAX. So once again, VO2MAX reflects how efficiently the heart, lungs, blood vessels, and mitochondria work together to deliver oxygen and produce energy and physical activity. Large studies involving tens of thousands of participants have shown that individuals with the largest levels of cardiorespiratory fitness can have 50 to 70% lower mortality risk compared with those with the lowest fitness levels. And the encouraging part is that VO2max is a modifiable metric. It can improve significantly with the right type of training. VO2MAX can be measured in several ways. It can be assessed through cardiopulmonary exercise testing, which is often performed in medical or sports performance laboratories, or through newer technologies that estimate VO2MAX using physiological measurements during exercise or at rest. Another important predictor of longevity is skeletal muscle mass and strength. Muscle is not just important for movement, it is a major metabolic organ, which we mentioned earlier.

SPEAKER_01 43:46

It stores glucose, it maintains insulin sensitivity, and it releases signaling molecules called myotines that influence metabolism, inflammation. And as we discussed in a previous podcast, it it's very Important in brain health.

SPEAKER_02 44:01

So loss of muscle mass, known as sarcopenia, is strongly associated with frailty, disability falls, and increased mortality. One of the simplest ways that researchers estimate overall strength and health is through grip strength testing, which has been shown in large population studies to correlate with the risk of cardiovascular disease and overall mortality. Muscle mass and body composition can be measured through tools such as texascans or bioimpedance devices or imaging technologies that estimate the muscle mass in visceral fat. Another important set of measurements involve metabolic health and insulin sensitivity. As we discussed earlier, insulin resistance can begin 10 to 20 years before diabetes is diagnosed. So measuring markers such as fasting insulin, fasting glucose, triglycerides, HDL cholesterol, and hemoglobin A1C can provide early insight into metabolic dysfunction. Many of these tests are available through routine laboratory testing ordered by a physician. So looking at the triglyceride to HDL ratio, for example, can provide useful insight into metabolic health and insulin sensitivity. Body composition is also extremely important. Two individuals may weigh the same but have different metabolic health depending on the amount of muscle mass and visceral fat that they carry. Visceral fat, that fat that is stored around the internal organs, is metabolically active and contributes to inflammation, insulin resistance, and cardiovascular disease. This type of fat can be measured with imaging tests, as mentioned before, such as DEXA scans, CT scans, and there's a bunch of advanced body composition analysis tools. Another important factor is inflammation. As we discussed earlier, it is inflammation is another biological signal that can provide insight into long-term health risk. Markers such as high sensitivity, CRP, or C reactive protein can indicate elevated levels of chronic inflammation. Even mild elevations and inflammatory markers have been associated with increased risk of cardiovascular disease and other chronic conditions. Another emerging area in longevity medicine involves measuring functional capacity and physical resilience. Metrics such as walking speed, balance, strength, exercise tolerance can often predict long-term health outcomes more accurately than static laboratory values alone. For example, slower walking speed in older adults has been associated with a higher mortality risk, highlighting how closely physical function is tied to overall biological health. When we combine these measurements, cardiorespiratory fitness, muscle mass and strength, metabolic markers, body composition, and inflammation, we begin to build a much clearer picture of someone's biological health and resilience. These metrics help us move beyond simply asking whether someone has a disease. Instead, we begin asking a different and much more meaningful question. How well is the body functioning? And that shift from diagnosing disease to measuring physiological resistance is really at the heart of longevity medicine. Because when we improve these systems, we're not just preventing one disease. We're improving the biology that determines how well we age.

SPEAKER_00 47:42

So I think that right now there's a lot of excitement around peptides, hormones, regenerative medicine, and a lot of other advanced tools as well. So where do these actually fit within the biology of aging?

SPEAKER_02 47:55

You're right. There's a lot of excitement around some of these emerging longevity technologies. People hear about peptides, hormone optimization, regenerative medicine, and other advanced therapies. And naturally they want to understand what these tools actually do and whether they truly can influence aging. The first thing to understand is that these therapies work best when they're layered on top of strong physiological foundations. The biology we discussed earlier in this episode, mitochondrial health, metabolic function, muscle mass, inflammation, and sleep still form the core of how the body ages. These systems regulate many of the hallmarks of aging. But once those systems are in place, modern longevity tools can sometimes help target specific biological pathways involved in repair, regeneration, and metabolic regulation. One category people hear about frequently today is peptide therapy. Peptides are short chains of amino acids that act as signaling molecules in the body. They're shorter versions of proteins. Typically, the cutoff is about 50 amino acids. But these peptides, they essentially, like proteins, they tell cells how to activate specific biological processes. Different peptides can influence different physiological systems. So for example, some peptides influence growth hormone signaling. Compounds such as CJC1295, epimorin, or tesimoralin stimulate the body's natural growth hormone pathways, which can influence muscle maintenance, fat metabolism, recovery, and cellular repair. Other peptides are studied for tissue repair and regenerative signaling. Peptides such as BPC157 and TB500, or thymic 500, have been investigated for their ability to support healing in musculoskeletal tissue, tendons, ligaments, and gastrointestinal tissue. There are also peptides that influence brain signaling and cognitive function, such as CMAX and that's S-E-M-A-X, or CELANC, S-E-L-A-N-K. They're being studied for their effects on neurochemical pathways related to mood, stress regulation, and cognitive performance. Another category involves mitochondrial and metabolic peptides such as MOTC, and that's M O T S-C or SS31. And they're being studied for their effects on mitochondrial efficiency, metabolic signaling, and cellular energy production. So another area that receives a lot of attention is, of course, hormone optimization. As we age, levels of several key hormones gradually decline. Hormones such as testosterone, estrogen, progesterone, growth hormone, DHEA influence many of the physiological systems involving muscle mass, bone density, metabolic health, cognitive function, and cardiovascular health. In individuals with clinically low hormone levels, restoring hormones to physiological ranges can sometimes improve energy, metabolic regulation, muscle maintenance, and quality of life. Another rapidly developing field is regenerative medicine. This involves therapies designed to stimulate the body's natural healing processes. For example, plately rich plasma or PRP concentrates growth factors from a patient's own blood that can be used to support tissue repair in joints, tendons, and in the skin. Another area receiving attention in regenerative medicine is exosomes. Exosomes are extremely small particles released by cells, particularly stem cells, that act as communication between cells. They carry molecules like proteins and RNA that help cells send instructions to other cells. So you can think of them as biological messaging packets that coordinate things like tissue repair, immune responses, and cellular regeneration. Much of the interest in exosomes comes from stem cell research, where scientists discovered that many of the regenerative effects of stem cells may actually come from the signals those cells release rather than the cells themselves. Those signals are often delivered through exosomes, so rather than replacing damaged tissue directly, exosomes appear to work by helping cells communicate and coordinate repair. Research in this area is still evolving, but it highlights some important cell-to-cell communication and healing and regeneration. Another category of therapies involves supporting cellular energy and metabolic function, compounds such as NAD-related therapies. These therapies aim to support cellular energy metabolism because NAD is a critical molecule involved in mitochondrial energy production and DNA repair. Other emerging compounds are being studied for their effects on metabolic pathways that regulate aging biology. The important point is that many of these therapies act on specific biological pathways. They may support tissue repair, metabolic signaling, hormonal balance, and cellular energy systems, but they are not substitutes for the broader physiological systems that regulate aging that we've discussed earlier. Exercise, nutrition, sleep, metabolic health, and maintaining muscle mass and influence multiple hallmarks of aging simultaneously. That's why they remain the foundation of longevity. Advanced therapies are best understood as tools that can complement those foundations. When used thoughtfully and in the right clinical context, some of these interventions may help support the body's natural repair systems or improve certain aspects of physiology. But the most powerful drivers of longevity still come from maintaining healthy biological systems over time. And that's really the philosophy of modern longevity medicine. Combining strong physiological foundations with carefully applied scientific tools that target specific pathways in aging biology. And ultimately, when we look at the science of aging, one thing becomes apparently clear. The biology that determines how long we live is deeply connected to the biology that determines how well our bodies function every day.

SPEAKER_00 54:40

And so today we explored something incredibly important that aging and chronic disease are not random events, but biological processes that we can really understand and influence. So if you are enjoying the Young Lab and learning how the body really works, make sure you subscribe and stay with us as we continue exploring the science behind living longer, stronger, and healthier. I definitely got so much from this episode. So thank you, Dr. Young, as always. And I cannot wait to see you next time. And we'll talk soon.

SPEAKER_02 55:09

Okay. Thanks. I appreciate it. It's great speaking with you again.