Is Muscle Loss Slowing Your Metabolism?
You may be eating about the same way you always have. Your activity level may not have changed much. The number on the scale may even be fairly stable.
But your body is changing.
Your waist is getting thicker. Your clothes fit differently. Fat seems to collect around your abdomen more easily. And losing a few pounds suddenly takes much more effort than it used to.
It’s easy to assume your metabolism has simply slowed down. But there may be another important piece of the story:
You may be losing muscle.
And as we age, preserving muscle becomes increasingly important for metabolism, body composition, bone health, and how well we function later in life.
You Can Weigh the Same and Have a Very Different Body
One of the problems with relying on the scale is that it tells you how much you weigh, but not what that weight is made of.
Imagine a woman who weighs 145 pounds and still weighs 145 pounds 10 years later.
It sounds like nothing has changed. But during those years, she may have lost muscle while gaining fat.
That can mean:
More abdominal fat
Less strength
Lower energy expenditure
Reduced insulin sensitivity
Greater difficulty maintaining weight
Less support for healthy bones
Gradual loss of physical function
Same weight does not mean same body composition.
This is why I am much more interested in body composition than just the number on the scale.
Muscle Is Metabolically Active Tissue
We tend to think about muscle in terms of strength or appearance. It is much more than that.
Skeletal muscle plays an important role in:
Glucose disposal and insulin sensitivity
Metabolic health
Strength and mobility
Balance and fall prevention
Supporting bone health
Maintaining physical independence as we age
When muscle mass declines, your body has less metabolically active tissue.
That does not mean losing a few pounds of muscle suddenly destroys your metabolism. Metabolism is more complicated than that.
But declining muscle can contribute to the larger metabolic shift many women experience as they get older, particularly when it occurs alongside hormonal changes, reduced activity, poor sleep, and changes in insulin sensitivity.
Why Does Muscle Become Harder to Maintain?
Muscle loss does not suddenly begin on a particular birthday. We gradually lose muscle with age, particularly if we are not actively giving the body a reason to maintain it.
For women, the menopause transition can add another layer.
Several changes may be happening at the same time:
Estrogen levels change, affecting body composition and fat distribution
Muscle becomes less responsive to anabolic signals, so maintaining or building it may require a stronger stimulus
Sleep often deteriorates, affecting recovery and energy
Activity may decrease, sometimes without us realizing how much
Insulin sensitivity can change, making body composition more difficult to maintain
There is also a phenomenon called anabolic resistance.
As we age, muscle becomes less responsive to the signals that stimulate muscle protein synthesis. In practical terms, your body may require a stronger stimulus from protein and resistance exercise than it did when you were younger.
Doing what you have always done may no longer be enough. How familiar does that sound??
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Why “Eat Less and Exercise More” Can Backfire
When weight starts creeping up, the instinct is often to cut calories and add more cardio. That may lower the number on the scale. But weight loss can include both fat and lean tissue.
This matters whether weight loss occurs through:
Calorie restriction
Significant increases in exercise
Bariatric surgery
GLP-1 medications
That is why I do not want my patients focused exclusively on how many pounds they have lost; I also want to know:
How much fat did you lose?
How much muscle did you preserve?
Did your body composition actually improve?
A smaller number on the scale is not automatically a better metabolic outcome.
If this sounds familiar, you may also want to read: Why Am I Gaining Weight When I’m Doing Everything Right?.
Walking Is Excellent. But Muscle Needs Resistance.
I am a big advocate of walking. It supports cardiovascular health, glucose regulation, mobility, mental health, and overall activity.
But walking and resistance training do different things.
The good news is that you do not need to live in the gym to make a difference. If you are not strength training now, two full-body workouts each week is a very reasonable place to start.
A Simple Beginner Strength Routine
Start with 2 nonconsecutive days per week, such as Tuesday and Friday. A basic full-body workout might include:
Squat or sit-to-stand: 2–3 sets
Hip hinge or Romanian deadlift: 2–3 sets
Row: 2–3 sets
Chest press or push-up: 2–3 sets
Shoulder press: 2–3 sets
Core exercise or loaded carry: 2–3 sets
For most exercises, 8–12 repetitions is a practical starting range. But the number of repetitions is not the most important part.
If building and preserving muscle is something you want to work on, you can also join my free Muscle & Longevity educational series.
The Weight Needs to Be Challenging
If you finish 10 repetitions and feel like you could easily do another 10, you are probably not providing enough resistance to stimulate meaningful adaptation.
Choose a weight that allows you to maintain good form but makes the last few repetitions genuinely difficult.
As you get stronger and that weight becomes easy, gradually increase the resistance.
You do not have to lift the heaviest weight possible, and beginners should learn proper technique before pushing intensity. But very light weights that you could lift indefinitely are unlikely to provide enough stimulus to build meaningful strength.
Don’t Know Where to Start?
You do not necessarily need a gym or personal trainer. Dumbbells, resistance bands, or body-weight exercises can be enough to get started.
There are also excellent free beginner resistance-training workouts available online. Look for programs that:
Include the major muscle groups (chest, back legs and glutes)
Teach proper form
Use progressive resistance
Allow you to increase the weight as you get stronger
Are appropriate for your current fitness and mobility level
A structured beginner workout can remove much of the uncertainty about what to do when you are first getting started.
Start twice a week. Challenge your muscles. Get stronger over time.
You Can’t Build Muscle Without Enough Protein
Resistance training provides the stimulus. Protein provides the building material.
This is one of the areas where I see women fall short, especially when they are trying to lose weight. They cut calories, but they also unintentionally cut the protein their body needs to preserve muscle.
A Simple Way to Estimate Your Protein Needs
Let’s use your goal body weight as a simple starting point:
Aim for approximately 0.8–1 gram of protein per pound of goal body weight per day.
For example:
Goal weight of 130 pounds → approximately 105–130 grams/day
Goal weight of 150 pounds → approximately 120–150 grams/day
Goal weight of 170 pounds → approximately 135–170 grams/day
You do not have to eat all of that protein at dinner. I generally recommend spreading it across 3–4 meals, often aiming for roughly 25–35 grams of protein at a time.
What Does 25–35 Grams of Protein Look Like?
Just get a general idea of what a protein-rich serving looks like:
1 scoop protein powder: approximately 25–30 grams
4–5 ounces chicken or fish: approximately 30–40 grams
3 eggs: approximately 18–20 grams
1 cup Greek yogurt: approximately 15–20 grams
1 tuna packet: approximately 17–20 grams
Some foods will need to be combined to reach that 25–35 gram range. Three eggs, for example, could be paired with Greek yogurt or another protein source.
Protein needs are not identical for everyone, particularly for people with certain medical conditions or kidney disease. But for most healthy adults trying to preserve or build muscle, getting enough total protein and distributing it throughout the day is a practical place to start.
And protein is only one part of the equation. Sleep, resistance training, hormones, and overall metabolic health all influence your ability to maintain muscle.
The Hormone, Muscle, and Metabolism Connection
The changes occurring during perimenopause and menopause do not happen in isolation.
Estrogen influences body composition, insulin sensitivity, bone, and skeletal muscle physiology. Testosterone also plays a role in muscle, bone, energy, and sexual function.
That does not mean every woman needs hormone therapy simply because she wants to preserve muscle.
It means that when I evaluate a woman whose body composition is changing, I do not view these as completely separate issues:
Hormones
Muscle
Metabolism
Weight
Sleep
Nutrition
Insulin sensitivity
Because they influence one another. That is why simply treating just one number on the scale often misses part of the picture.
Can Technology Help Build Muscle?
Technology can also be useful, but expectations matter.
I love Emsculpt Neo to stimulate intense muscle contractions while simultaneously delivering radiofrequency energy.
I consider it an adjunct to a muscle-building strategy, not a replacement for:
Resistance training
Adequate protein
Regular physical activity
Addressing hormonal or metabolic issues when appropriate
For the right patient, it can be another tool to stimulate muscle while we work on the other factors affecting body composition. But no device replaces the fundamentals.
Stop Letting the Scale Be the Only Scorecard
How do you know how much of your weight is fat vs muscle? You can use InBody body composition testing at Foundations.
Instead of simply seeing that you weigh 145 pounds, it measures changes in:
Skeletal muscle mass
Body fat
Body fat percentage
Visceral fat estimates
Body composition over time
This becomes particularly valuable during weight loss.
You may have lost six pounds which feels great! But if you lost predominantly fat while maintaining or increasing muscle, I may consider that a much better outcome than losing 15 pounds that included a substantial amount of lean tissue.
Muscle Is Part of Your Longevity Strategy
Muscle becomes more important as you get older, not less.
Preserving it supports:
Metabolic health
Glucose regulation
Bone health
Strength
Balance
Mobility
Physical independence
So if your body seems to be changing even though your habits have not changed very much, do not automatically assume the answer is simply eating less.
The number on the scale is only one piece of the picture.
Are you building and preserving enough muscle to support the way you want to age?
Maintaining muscle isn’t just about looking stronger. It helps protect your metabolism, your bones, your strength, your mobility, and your independence.
What your body is made of, and what it will allow you to do 10, 20, and 30 years from now, matters far more than a number on the scale.
Frequently Asked Questions
Does metabolism really slow down as we age?
Energy expenditure can change with age, but there is not a metabolic switch that suddenly flips at a certain birthday. Changes in muscle mass, physical activity, hormones, sleep, body composition, and metabolic health can all contribute to what people experience as a “slower metabolism.”
Can you lose muscle even if your weight stays the same?
Yes. You can lose muscle while gaining fat and remain at approximately the same body weight. This is one reason body composition measurements can provide information that a standard scale cannot.
Does menopause cause muscle loss?
The menopause transition is associated with changes in body composition, and hormonal changes may contribute. Aging, physical activity, nutrition, sleep, and other factors also affect muscle, so menopause is only one part of the picture.
Is walking enough to prevent muscle loss?
Walking is excellent exercise, but resistance training provides a stronger stimulus for maintaining and building skeletal muscle. Two full-body resistance-training sessions per week is a reasonable starting point for many people.
How much protein should I eat to maintain muscle?
For many of my patients, I use approximately 0.8–1 gram of protein per pound of goal body weight per day as a practical starting point, generally divided across several meals. Individual needs vary based on health, activity level, body size, and other factors.
Can GLP-1 medications cause muscle loss?
Weight loss with GLP-1 medications can include both fat mass and lean mass. This makes adequate nutrition, sufficient protein, resistance exercise, and monitoring body composition particularly important during significant weight loss.
How can I measure muscle mass?
Body composition tools such as InBody can estimate skeletal muscle mass and body fat and allow us to follow changes over time. DEXA can also provide information about body composition.
Can Emsculpt Neo replace strength training?
No. Emsculpt Neo can be used as an adjunct to stimulate muscle, but it should not replace resistance exercise, adequate nutrition, or regular physical activity.
Listen to Dr Jackson discuss these topics on her podcast, Ageless and Outrageous agelessandoutrageous.alitu.com
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