Why Muscle Is the Best Investment You Can Make in Your Long-Term Health

Built to Move · Episode 1, Part 1 · Featuring strength coach Kurt Smith

If you are over 40 and your main health goal is "lose weight," this episode of Built to Move might change your mind. Strength coach Kurt Smith argues that the better goal for most people is to build muscle. Muscle is one of the few parts of your body you can directly change at any age, and it shapes how well you move, how your body handles blood sugar, how strong your bones stay, and how independent you remain as you get older.

Kurt has been competing for more than 11 years, coaching personal training clients for over 10 years, and working with competitive bodybuilders for the past five. In this first part of Episode 1, he explains why muscle matters, why we lose it, how much you actually need, and how to measure it without getting fooled by your BMI.

Prefer to watch? The full episode is on the Movement Health YouTube channel: watch Built to Move Episode 1, Part 1. Want to keep this guide handy? Download the free PDF version of this article with frequently asked questions at the bottom of this page.

Why Is Muscle So Important for Your Health?

Muscle matters because it does far more than move your body. Skeletal muscle helps regulate blood sugar, supports a healthy metabolism, stabilizes your joints, loads your bones so they stay strong, and is linked to lower risk of chronic disease. In short, muscle affects almost every system that determines how well you age.

Kurt summed up the list in the episode: muscle helps regulate blood sugar, helps you avoid chronic disease and chronic inflammation, improves your metabolism, supports bone health and even benefits cognitive health. Research backs up the big ones:

• Blood sugar: Skeletal muscle is the main tissue that pulls sugar out of your bloodstream after a meal. Less muscle means less room to store that sugar, which is one reason age-related muscle loss is tied to insulin resistance.
• Bones: Muscles pull on bones every time they contract. Meta-analyses show resistance training improves bone mineral density in postmenopausal women, especially at the spine and hip.
• Joints and pain: Strong muscles around the knees, hips, core and shoulders keep joints stable and take load off irritated tissues.
• Daily function: Lifting groceries, getting up from the floor, carrying grandkids and putting dishes on a high shelf all depend on strength.

Is Muscle an Organ?

Technically, muscle is a tissue, but scientists now describe skeletal muscle as an endocrine organ. When muscles contract, they release signaling molecules called myokines into the bloodstream. These messengers communicate with fat tissue, the liver, the pancreas, bones and the brain, which helps explain why exercise benefits so many parts of the body at once.

As Kurt put it, muscle "acts like an organ." It synthesizes and releases hormone-like messengers that affect the rest of your body, which is one more reason to treat it as a vital part of your health and not just something for the beach.

Why Aren't More People Talking About Muscle?

Most routine health conversations still focus on body weight. In Kurt's experience, a typical check-up is more likely to end with "you should lose some weight" than "you should build some strength." Social media and the fitness world have started shifting the conversation toward muscle, but many people still have never been taught why it matters.

That is starting to change. Current U.S. Physical Activity Guidelines recommend that adults do muscle-strengthening activities that work all major muscle groups on 2 or more days a week, on top of their aerobic activity. If strength training has never come up at your appointments, it is worth asking your doctor or physical therapist about it directly.

Why Do We Lose Muscle as We Age?

We lose muscle as we age for two main reasons: hormone changes and doing less physical activity. Muscle is a "use it or lose it" tissue. When you stop challenging it, your body stops investing energy in keeping it, and the muscle gradually shrinks (atrophy). This age-related loss of muscle mass and strength is called sarcopenia.

Kurt sees the activity piece constantly in his clients. Many people, especially those who worked physically demanding jobs, reach a point where they feel they have earned the right to slow down. Rest is good, but stopping physical exertion altogether speeds up muscle loss.

When Does Muscle Loss Start?

Muscle loss starts earlier than most people think and speeds up later in life. A large MRI study of 468 adults found that relative muscle mass begins declining as early as the third decade of life, with a more noticeable drop in total muscle after about age 50, mostly in the legs. Research on older Americans has also found low muscle mass is more common in older women than older men.

Kurt's observation from coaching lines up with this: women tend to notice the effects in their 50s, while many men do not feel it until later. He also sees shoulder strength drop off sharply in clients starting around age 40, which is why it is one of the first things he tests.

Why Don't People Notice It Happening?

Because the change is tiny from day to day. You do not notice losing a little strength this month. Then one day, years later, you realize it is hard to get off the floor or lift a bag into the overhead bin. Kurt describes it as small missed steps that add up until people look back and ask, "How did I get this far?" The good news is that muscle responds to training at every age, so it is never too late to start.

Why Should You Care About Muscle at 45 or 55?

If you are in your 40s or 50s, building muscle is one of the most effective ways to reduce everyday aches, protect your joints and keep daily tasks easy. Stronger muscles stabilize your knees, back and shoulders, which can reduce pain and lower your risk of injury.

• Knee pain: Stronger quads, hamstrings and hips help stabilize the knee joint and absorb load.
• Back pain: Core and hip strength supports the spine during bending, lifting and twisting.
• Shoulder weakness: Kurt regularly works with middle-aged and older women who can no longer put plates up in a cabinet because their shoulders are too weak. Simple tasks like this become hard long before most people expect.
• Independence: The strength you build now is the strength you will have to draw on in your 70s and 80s.

What Does Healthy Muscle Look Like If You're Not a Bodybuilder?

Healthy muscle is not about looking like a competitor on stage. It is about having enough muscle relative to your body weight to stay strong, metabolically healthy and independent. Kurt uses two simple benchmarks with his clients.

Healthy Skeletal Muscle Percentage

Skeletal muscle is the muscle attached to your bones that you train in the gym. Kurt's general targets:

• Men: about 35-45% of total body weight as skeletal muscle
• Women: about 23-35% of total body weight as skeletal muscle

For reference, the 468-person MRI study mentioned above found average skeletal muscle of about 38% of body mass in men and about 31% in women, so these ranges are realistic for everyday adults.

Healthy Lean Mass Percentage

Lean mass is a broader number that includes muscle, bone, organs and water (everything that is not fat). Kurt's general targets:

• Men: roughly the high 70s to high 80s percent of total body weight
• Women: roughly the high 60s to high 70s percent of total body weight

These are coaching guidelines, not diagnostic cut-offs. Your ideal range depends on your age, sex, health history and goals.

Is There Such a Thing as Enough Muscle?

Yes. For the average person, landing within the ranges above is enough to support long-term health. Athletes and bodybuilders will naturally carry more, but you do not need an extreme physique to get the health benefits of muscle.

How Do You Measure Your Muscle Mass?

The easiest ways to measure muscle mass are a body composition scan at a gym, clinic or supplement store, or an at-home smart scale tracked over time. You do not need a perfect number. You need a consistent way to see whether your muscle is going up or down.

• At-home smart scales (bioelectrical impedance): These send a small, painless electrical current through electrodes under your feet. Because fat and lean tissue conduct electricity differently, the scale estimates your body fat and muscle. Many cost around $20-$50. They are not perfectly accurate, and readings shift with hydration, food and recent exercise, so weigh in at the same time of day under the same conditions and focus on the trend.
• In-clinic body composition scans (such as InBody): These use the same electrical impedance principle with more sensors and tend to be more consistent. Some gyms, supplement stores and health centers offer them, sometimes for around $10 even if you are not a member.
• DEXA scan: Considered one of the most accurate options, a DEXA scan uses very low-dose X-rays to measure fat mass, lean mass and bone density by body region. It costs more but gives the most detailed picture.

Why BMI Can Mislead You

BMI (body mass index) only uses your height and weight. It cannot tell the difference between a pound of muscle and a pound of fat, so muscular people often get labeled "overweight" or "obese" when they are not. BMI is useful for studying large populations, but it is a poor tool for judging one person's health.

Kurt is a perfect example. His BMI is close to 40, which falls in the severely obese category on a standard chart. In reality, he is under 10% body fat. The chart cannot see that most of his weight is muscle. If you are active or strength training, track body composition, not just BMI.

Can You Get Healthier Without Looking Dramatically Different?

Absolutely. You do not need to transform into a bodybuilder to become healthier. That said, a nice side effect of building muscle is that you usually look better too. Strength training builds the shape most people want, and combined with sensible eating, it helps shift your body composition toward less fat and more muscle.

One honest note on metabolism: muscle does burn more calories at rest than fat, but the difference per pound is modest (roughly 6 calories a day for muscle versus about 2 for fat). The bigger calorie impact comes from the training itself, being more active overall, and the better blood sugar control and appetite regulation that come with being stronger. Do not count on muscle alone to melt fat; pair it with good nutrition.

What Happens in Your Body When You Add 5 Pounds of Muscle?

Adding about 5 pounds of lean muscle is a meaningful change. Kurt points to several benefits, and the research supports them:

1. Better insulin sensitivity: More muscle gives your body more places to store blood sugar, which helps keep glucose levels steady and energy more consistent.
2. A slightly higher resting metabolism: Expect roughly 30 extra calories burned per day at rest from 5 pounds of muscle, plus more during activity.
3. Stronger bones: The training needed to build that muscle loads your bones and supports bone mineral density.
4. Better mood and mental clarity: Regular strength training is associated with improved mood, energy and focus.
5. Easier daily life: Stairs, carrying, lifting and getting up from the floor all get easier, and joints feel more supported.

This Week's Built to Move Challenge: Two Full-Body Strength Workouts

Kurt's challenge for this episode is simple: complete two full-body strength workouts this week. They can be bodyweight only. Pay attention to how you feel before and after each one, then tell us how it went in the YouTube comments.

Not sure where to start? Here is a simple beginner full-body routine you can do at home. Perform 2-3 rounds, 8-12 reps each, resting as needed:

1. Sit-to-stand or bodyweight squat: Stand up from a chair and sit back down with control. Works legs and hips.
2. Incline push-up: Hands on a kitchen counter or sturdy table. Works chest, shoulders and arms.
3. Glute bridge: Lie on your back, knees bent, and lift your hips. Works glutes and supports the low back.
4. Bent-over row: Use a resistance band, backpack or light dumbbells. Works the upper back and shoulders.
5. Bird dog: On hands and knees, reach opposite arm and leg. Builds core stability.
6. Wall slide or overhead reach: Slide your arms up a wall with control. Supports shoulder mobility and strength.

Move slowly, stay in a pain-free range, and stop if anything feels sharp. If you are recovering from surgery or an injury, or you have a heart, joint or other medical condition, check with your doctor or physical therapist before starting a new program.

The One Thing to Remember: Build Muscle

When asked what he would want viewers to remember from this conversation, Kurt kept it simple: build muscle. If you have time to watch TV or scroll your phone for an hour, you have time for 30-40 minutes of strength training. It is one of the best things you can do for your life. You will live longer, live healthier, feel better and have more energy, and if you have kids, you will be around and able to keep up when they have kids of their own.

Frequently Asked Questions About Muscle and Aging

How much muscle should I have?

As a general coaching guide, men can aim for about 35-45% of body weight as skeletal muscle and women about 23-35%. For lean mass (everything that is not fat), men are typically in the high 70s to high 80s percent and women in the high 60s to high 70s percent.

Is BMI a good measure of health?

Not on its own. BMI only uses height and weight and cannot tell muscle from fat. Muscular people are often labeled overweight or obese by BMI even with low body fat.

How often should I strength train?

U.S. guidelines recommend muscle-strengthening activities for all major muscle groups at least 2 days a week, in addition to aerobic activity like walking.

Do I need a gym to build muscle?

No. Bodyweight exercises like sit-to-stands, incline push-ups, glute bridges and bird dogs work well, and resistance bands or light weights help you progress.

Can strength training help with knee, back or shoulder pain?

Often, yes. Stronger muscles stabilize joints and the spine and take stress off irritated tissues. If you have an injury or recent surgery, follow your physical therapist's guidance on what to start with.

Is it too late to start building muscle?

No. Muscle responds to training at any age. Start with light, controlled exercises and build gradually.

Watch the Full Episode and Keep Moving

Want to hear Kurt explain all of this in his own words? Watch the full Built to Move Episode 1 (Part 1 of 3) on our YouTube channel. Subscribe to Movement Health by Supply Physical Therapy so you do not miss Parts 2 and 3.

Then take the challenge: two full-body strength workouts this week. Like, subscribe, and comment down below to let us know how you felt and what health, fitness, nutrition or longevity topics you want us to cover next. Your question might become a future episode.

Download the Free PDF Guide

Want this information in one place? Download the free PDF version of this article, including a frequently asked questions sheet on muscle, aging and your health. It is easy to print, save to your phone or share with a family member who needs the reminder to start building muscle.

Download the Free PDF + FAQ

To learn more or work with Kurt directly, follow him on Instagram at @kurtsmith_fit and @temple_coaching.

Sources and Further Reading

• CDC: Adult Activity, An Overview (Physical Activity Guidelines for Americans)
• Janssen et al. (2000). Skeletal muscle mass and distribution in 468 men and women aged 18-88 yr. Journal of Applied Physiology.
• Muscle as a paracrine and endocrine organ (2017). Current Opinion in Pharmacology.
• Paquin et al. (2021). Exercising for insulin sensitivity: is there a mechanistic relationship with skeletal muscle mass? Frontiers in Physiology.
• Zhao et al. (2025). Optimal resistance training parameters for improving bone mineral density in postmenopausal women. Journal of Orthopaedic Surgery and Research.
• Body composition assessment methods in sport (BIA, DXA and more). Review, PMC.

This article is for educational purposes and is not a substitute for individual medical advice.