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Men, Muscle, and Metabolism: What You Need to Know After 40

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Board-certified in Obesity and Emergency Medicine, with advanced training in Anti-Aging & Regenerative Medicine—Dr. De Leon blends science and soul to deliver truly personalized care.

Dr. Marilin De Leon, DO

Your strength isn’t just about how you look—it’s about how you age.

At De Leon Precision Medicine, we work with men who feel like their bodies aren’t keeping up anymore: weight gain around the middle, low energy, poor recovery, and workouts that no longer deliver the same results.

If you’re over 40, it’s not just your imagination. Shifts in hormones, metabolism, and muscle mass are a natural part of aging—but that doesn’t mean you’re stuck with them.

Let’s break down what’s really going on—and how you can work with your body to stay strong, lean, and sharp for decades to come.

Muscle Mass After 40: Why It Declines

By the time you hit your 40s, your lean muscle mass begins to decrease by 3–8% per decade, a process known as sarcopenia. Combine that with falling testosterone levels, and suddenly:

  • You gain fat more easily (especially around the midsection)
  • It takes longer to recover from workouts
  • Energy, mood, and drive start to dip
  • Your metabolism slows down—even if your habits haven’t changed

This is biology, yes—but it’s also fixable.

Why Muscle Is Metabolically Active

Muscle does more than help you lift weights. It’s a metabolically active tissue that helps:

  • Burn fat at rest
  • Stabilize blood sugar and insulin levels
  • Support testosterone production
  • Improve mitochondrial (cellular energy) function
  • Reduce inflammation and oxidative stress

The more lean muscle you maintain, the more your metabolism stays efficient—even as you age.

Common Signs Your Metabolism Is Shifting

If you’re noticing any of these, it may be time to test—not guess:

  • Weight gain despite exercise
  • Low motivation or mood swings
  • Sleep disruptions
  • Slow recovery or muscle loss
  • Decreased libido or performance
  • Brain fog or trouble focusing

At De Leon Precision Medicine, we use advanced lab testing to look beyond standard panels. We assess:

Testosterone & Free T
DHEA, cortisol & insulin levels
Thyroid function
Inflammatory markers
Body composition—not just BMI

What You Can Do Right Now

Here are 5 steps that support muscle and metabolism in men over 40:

1. Prioritize Resistance Training

Focus on compound movements (squats, deadlifts, pull-ups, presses) at least 2–3x/week to build and preserve lean muscle.

2. Get Enough Protein

Most men don’t eat enough high-quality protein. Aim for 0.8–1.0g per pound of lean body mass.

3. Test Your Testosterone

Low T is common—and treatable. We offer bioidentical and integrative strategies to help restore your balance.

4. Dial In Recovery

Good sleep, active recovery, hydration, and stress reduction are essential to keep your workouts effective and your hormones balanced.

5. Stay Consistent

It’s not about perfection. It’s about stacking habits that support your long-term strength and vitality.

Being strong after 40 isn’t just about looking good—it’s about protecting your metabolic health, your hormone function, and your future.

We help men identify what’s working, what’s not, and what’s next—so you can move forward with clarity, energy, and real results.

Ready to optimize your strength and metabolism—backed by science, not guesswork?
Book Your Free Discovery Call

x

Your strength isn’t just about how you look—it’s about how you age.

At De Leon Precision Medicine, we work with men who feel like their bodies aren’t keeping up anymore: weight gain around the middle, low energy, poor recovery, and workouts that no longer deliver the same results.

If you’re over 40, it’s not just your imagination. Shifts in hormones, metabolism, and muscle mass are a natural part of aging—but that doesn’t mean you’re stuck with them.

Let’s break down what’s really going on—and how you can work with your body to stay strong, lean, and sharp for decades to come.

Muscle Mass After 40: Why It Declines

By the time you hit your 40s, your lean muscle mass begins to decrease by 3–8% per decade, a process known as sarcopenia. Combine that with falling testosterone levels, and suddenly:

  • You gain fat more easily (especially around the midsection)
  • It takes longer to recover from workouts
  • Energy, mood, and drive start to dip
  • Your metabolism slows down—even if your habits haven’t changed

This is biology, yes—but it’s also fixable.

Why Muscle Is Metabolically Active

Muscle does more than help you lift weights. It’s a metabolically active tissue that helps:

  • Burn fat at rest
  • Stabilize blood sugar and insulin levels
  • Support testosterone production
  • Improve mitochondrial (cellular energy) function
  • Reduce inflammation and oxidative stress

The more lean muscle you maintain, the more your metabolism stays efficient—even as you age.

Common Signs Your Metabolism Is Shifting

If you’re noticing any of these, it may be time to test—not guess:

  • Weight gain despite exercise
  • Low motivation or mood swings
  • Sleep disruptions
  • Slow recovery or muscle loss
  • Decreased libido or performance
  • Brain fog or trouble focusing

At De Leon Precision Medicine, we use advanced lab testing to look beyond standard panels. We assess:

Testosterone & Free T
DHEA, cortisol & insulin levels
Thyroid function
Inflammatory markers
Body composition—not just BMI

What You Can Do Right Now

Here are 5 steps that support muscle and metabolism in men over 40:

1. Prioritize Resistance Training

Focus on compound movements (squats, deadlifts, pull-ups, presses) at least 2–3x/week to build and preserve lean muscle.

2. Get Enough Protein

Most men don’t eat enough high-quality protein. Aim for 0.8–1.0g per pound of lean body mass.

3. Test Your Testosterone

Low T is common—and treatable. We offer bioidentical and integrative strategies to help restore your balance.

4. Dial In Recovery

Good sleep, active recovery, hydration, and stress reduction are essential to keep your workouts effective and your hormones balanced.

5. Stay Consistent

It’s not about perfection. It’s about stacking habits that support your long-term strength and vitality.

Being strong after 40 isn’t just about looking good—it’s about protecting your metabolic health, your hormone function, and your future.

We help men identify what’s working, what’s not, and what’s next—so you can move forward with clarity, energy, and real results.

Ready to optimize your strength and metabolism—backed by science, not guesswork?
Book Your Free Discovery Call

10/11/25

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— Dr. Marilin De Leon, DO

“If you’ve been told everything looks normal but still don’t feel like yourself — I want you to know: you’re not alone, and you’re not imagining it. We take the time to truly listen and get to the root of what’s going on. You deserve answers, and that’s what we’re here to find.”

Board certified physician with advanced training through the American Academy of Anti-Aging & Regenerative Medicine and Columbia University’s Obesity Medicine program

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We combine cutting-edge lab testing, advanced diagnostics, and evidence-based integrative therapies to craft care plans that align with your biology, lifestyle, and goals. We take time to educate, guide, and support you—because healing happens best when you’re not rushed or unheard.