Why Women Lose Muscle After 40 — And Exactly How to Stop It

I didn't know I was losing muscle. I just knew something felt different. Here's what I wish someone had told me at thirty-five.

I didn't notice it as muscle loss at first.

I noticed it in the water.

Surfing has been part of my life for years. And somewhere around thirty-nine, forty, I started feeling anxious out there in a way I hadn't before. When the waves got bigger, something shifted. I wasn't feeling stable. I wasn't feeling like myself. I've always had a strong body — sport has been part of my life since I was a child — but something was quietly changing, and I couldn't name it yet.

It wasn't until much later that I understood what was happening. From around thirty-five onwards, women begin losing muscle mass. Not dramatically at first. Gradually. Quietly. And it's not only hormonal — though the hormonal piece matters enormously. It's also simply age-related. The body changes. And if we don't change what we ask of it, we feel the consequences without ever knowing why.

I didn't know any of this at the time. I just knew something needed to change.

So Why Do Women Lose Muscle After 40 & What That Feels like

At thirty-five you're not thinking about sarcopenia — the clinical term for age-related muscle loss. You're not thinking about oestrogen's role in muscle protein synthesis, or the fact that without intervention, women can lose three to five percent of their muscle mass per decade from their thirties onwards, accelerating significantly in perimenopause.

You're just living your life. And then one day you feel less stable than you used to. Or more tired doing things that used to feel easy. Or you notice your body isn't responding the way it did in your twenties and thirties, no matter what you do.

For me it became undeniable after I had my daughter. I was forty-one. I'd had a C-section. I'd been breastfeeding. My hip, which had been niggling for years, felt genuinely weak. And I remember thinking — I need to rebuild. Not stretch. Not flow. Build.

That instinct was right. And it changed everything.

What Most Women Try First — And Why It Doesn't Work

Here's what I see, over and over again, in women who come to me in their forties feeling like something is off.

They're doing exactly what they did in their twenties and thirties. High cardio. Lots of yoga. Bodyweight classes. Passive flexibility. Things they love, things that feel familiar, things that served them well for years.

And they can't understand why it isn't working anymore.

I was the same. I kept doing my yoga, kept surfing, kept moving — and I wasn't feeling better. I was feeling less. Less strong, less stable, less capable.

The honest truth is that cardio and flexibility work, on their own, do not stop muscle loss. They don't send the signal your body needs to hold onto and build muscle tissue. For that, you need resistance. You need progressive load. You need to ask your muscles to work harder over time.

This is not about abandoning what you love. I still surf. I still hike. My daughter and I walk in the hills near our home in Cantabria and I want to be doing that with her when I'm seventy, eighty. That's not a fantasy — it's a plan. And that plan requires muscle.

What Actually Stops Muscle Loss After 40

Let me be clear about the science here, because I think there's a lot of confusion, why women lose muscle after 40 — even in the perimenopause wellness space.

You do not need to lift maximally heavy to build muscle. That's one way, but it's not the only way. Research now shows clearly that higher reps with lighter weight can produce the same muscle hypertrophy as lower reps with heavier weight — as long as you train close to failure.

That last part is important. Close to failure. Not stopping when it gets uncomfortable. Continuing with good form, no compensation, until the muscle has genuinely been challenged.

This is exactly what we do in SoulSculpt Method — honestly, before I even had the language for it. I'd watch women in class looking at me like how much longer and the answer was: until you can't. Until the muscle shakes. Until it's done. With form intact, with breath, with control — but genuinely done.

That's where muscle is built.

What you also need, and this is the part most strength programs for women over 40 skip, is adequate protein. Most women are significantly under-eating protein. For muscle synthesis after 40, you need more than you think — around 1.6 to 2 grams per kilogram of body weight daily, spread across meals.

And sleep. Muscle is built during recovery, not during training. If you're training consistently but sleeping poorly, the results will be slower than they should be.

Why Strength x Pilates Specifically Works for This

I want to explain why the combination matters — not just the strength piece alone.

When oestrogen declines, your connective tissue becomes less forgiving. Tendons and ligaments lose some of their resilience. This means that loading movements without the body awareness and control to support them leads to exactly the compensation patterns and injuries that stop women training altogether.

And if you stop training, the muscle loss accelerates.

Strength x Pilates solves this by building the foundation first. The Pilates element — the breath, the alignment, the precise muscular awareness — means that when load is added, it goes where it's supposed to go. The right muscles do the work. The joints are protected. And you can keep progressing, week after week, without the setbacks.

This is not a gentle approach. In a SoulSculpt session, we work hard. We go to failure in controlled movements. We challenge the body seriously. But we do it intelligently — and that intelligence is what makes it sustainable over years, not just weeks.

What a Real Week Looks Like

I want to give you something practical, because I think the idea of "strength training" can feel like a big commitment that doesn't fit a real life.

It doesn't have to be.

Two SoulSculpt sessions a week — live on Thursdays or from the replay library — is already a meaningful start. Forty-five minutes, full body, Strength x Pilates integrated. That alone, done consistently, begins to change things.

If you want to go further: one or two additional shorter strength sessions per week, thirty minutes, focused on whatever your body needs. And walking — genuinely, just walking regularly. For your bones, your cardiovascular health, your nervous system, your head.

That's four sessions. Around three hours a week total. And it is enough to stop muscle loss in its tracks and start building back.

I know this because I've lived it. I breastfed for three years. I went into perimenopause. I had a C-section at forty-one and rebuilt from there. And at forty-six, training this way, I have genuinely never felt stronger or more capable in my body.

Not despite being in my forties. Because of what I've built in them.

It's Not Too Late

I want to say this clearly, because I think some women read about muscle loss and feel like they've already missed their window.

You haven't.

The body responds to resistance training at every age. Women in their fifties, sixties, seventies show measurable muscle growth when they train with progressive load. The window doesn't close — it just requires a different key.

Start where you are. Build from there. Stay consistent.

That's it. That's the whole thing.

Every Thursday at 10:15 CET, we train live online — Strength x Pilates, built specifically for women navigating perimenopause and beyond. Can't make it live? Every session is recorded. Unlimited replays, no expiry, train whenever your week allows.

Your first week is free.

→ [Start your free 7-day trial at soulsculptmethod.com]

Or keep reading:

• [How to Start Strength Training After 40 Without Getting Hurt]

• [Pilates or Strength Training After 40 — Do You Have to Choose?]

• [Do Women Over 40 Need Heavy Weights?]

Shaini Verdon is the founder of SoulSculpt Method. E-RYT 500, Pilates instructor, NASM Women's Fitness Specialist, FRC Mobility Specialist, certified in Dr Stacy Sims' Menopause 2.0 protocol. Based in Cantabria, northern Spain.