GLP-1 medications can be incredibly effective tools for improving metabolic health and helping people lose weight. But after 40—especially for women—there is another part of the conversation that I think deserves much more attention:
What are you losing along with the weight?
Because losing 25 pounds isn’t necessarily a metabolic win if you also lose a significant amount of muscle, stop eating enough protein, become nutritionally depleted and feel weaker than you did before.
This becomes particularly important during perimenopause and menopause, when changes in estrogen, testosterone, insulin sensitivity, sleep and body composition are already making it easier to gain visceral fat and harder to maintain muscle.
So when I use GLP-1 medications with patients at Boulder Holistic Functional Medicine in Boulder, Colorado, my goal isn’t simply weight loss.
It’s better body composition, better metabolic health and better aging.
The Scale Doesn’t Tell You What You’re Losing
When we lose weight, we don’t lose exclusively body fat. Some degree of lean-mass loss occurs with almost any significant weight reduction, whether the weight is lost through calorie restriction, bariatric surgery or medication. GLP-1 medication induced weight loss is not an exception.
In a body-composition substudy of the SURMOUNT-1 tirzepatide trial, approximately 75% of the weight lost was fat mass and about 25% was lean mass.
That doesn’t mean 25% was necessarily skeletal muscle—“lean mass” also includes water and other non-fat tissues—but it does highlight an important point:
We should care about the quality of weight loss, not just the quantity. If someone loses 30 pounds, I want as much of that loss as possible to come from excess body fat while preserving muscle, strength and bone.
Why Muscle Matters So Much After 40
I think we’ve spent decades teaching women to care about being thin when we should have been teaching them to care about being strong.
Muscle isn’t just something that makes your arms look toned. Skeletal muscle is metabolically active tissue.
It helps:
- Dispose of glucose
- Improve insulin sensitivity
- Support metabolic rate
- Maintain balance and mobility
- Protect bone
- Preserve physical independence
- Support healthy aging
We naturally begin losing muscle as we age, and that process accelerates later in life.
For women, the menopausal transition adds another layer. Changes in estrogen and other hormones can influence body-fat distribution, muscle, bone, sleep, insulin sensitivity and recovery.
So if you’re a 50-year-old woman entering menopause and you’re losing weight rapidly on a GLP-1 and you’re barely eating protein and you’re not strength training, you may be creating the perfect environment for accelerated muscle loss. That’s exactly what I don’t want.
Rule #1: Protein Becomes Non-Negotiable
One of the first things I talk about with GLP-1 patients is protein. These medications suppress appetite—which is obviously part of why they work. But sometimes they work a little too well.
After starting a GLP-1 medication, I ask patients to tell me what they actually ate that day:
Coffee.
Half a yogurt.
Maybe some crackers.
A small dinner.
That is not adequate nutrition!
If you’re eating substantially less food, the nutritional quality of the food you do eat becomes even more important. And, protein should usually be prioritized first.
The exact amount needs to be individualized based on body size, age, kidney function, activity level and medical history, but for many adults trying to preserve muscle during weight loss, I often think in the range of approximately: 1.0–1.2 grams of protein per kilogram of body weight per day as a target.
Mostly, rather than obsessing over a perfect number, I often start with something simpler: Put a meaningful source of protein at every meal.
Eggs. Greek yogurt. Cottage cheese. Fish. Chicken. Turkey. Lean meat. Tofu. Tempeh. Legumes. Protein shakes.
If appetite is low, a good-quality protein shake can be extremely useful.
And don’t save all of your protein for dinner. Spreading protein throughout the day gives your muscles repeated opportunities for muscle protein synthesis.
Rule #2: Lift Something Heavy
Walking is fantastic. I want you walking. Walking helps cardiovascular health, glucose regulation, mood, mitochondrial health and longevity.
But walking alone is not enough to tell your body to keep muscle. Resistance training provides that signal.
That can mean:
- Weights
- Resistance bands
- Machines
- Body-weight exercises
- Pilates with meaningful resistance
You don’t have to become a bodybuilder.
But your muscles need to encounter enough resistance that they have a reason to adapt. For many people, 2–3 resistance-training sessions per week is an excellent place to start.
And ideally, the resistance gradually increases as you become stronger. The goal isn’t simply exercise. The goal is progressive load.
Creatine Isn’t Just for Bodybuilders
Creatine is one supplement I think deserves much more attention in midlife and longevity medicine.
Most people associate creatine with young men lifting weights. I believe that is outdated.
Creatine helps regenerate ATP—the energy currency used by muscle and other tissues—and has a substantial body of research supporting its ability to improve strength and training performance when combined with resistance exercise.
There is also growing interest in creatine for cognition and healthy aging.
For many adults, creatine monohydrate around 3–5 grams daily is a simple and well-studied option.
It isn’t mandatory for someone taking a GLP-1. But for the right patient—particularly someone over 40 who is strength training and actively trying to preserve muscle—I think it’s worth considering.
Don’t Forget About Carbohydrates
The pendulum has swung so far toward low-carb eating that sometimes people become afraid of carbohydrates altogether. For someone with significant insulin resistance, carbohydrate quality and quantity absolutely matter. But carbohydrates aren’t inherently bad.
If you’re strength training, moving regularly and trying to preserve muscle, strategically including whole-food carbohydrates can support exercise performance, recovery and thyroid and reproductive physiology.
Think: fruit, berries, beans, lentils, quinoa, oats, sweet potatoes and other minimally processed sources.
The goal isn’t: eat as little as possible. The goal is: eat enough of the right things to support a healthier body.
Your Hormones Still Matter
This is where I think the GLP-1 conversation sometimes becomes overly simplistic.
A woman in her late 40s may come in saying: “I suddenly gained 15 pounds and nothing I’m doing works anymore.”
And yes, insulin resistance may be part of that. But so may perimenopause. Estrogen influences much more than reproduction.
The menopausal transition is associated with changes in:
- Visceral fat
- Insulin sensitivity
- Muscle and body composition
- Bone density
- Sleep
- Mood
- Temperature regulation
- Cardiovascular risk
Poor sleep from night sweats can then worsen insulin resistance and appetite regulation.
Loss of muscle can further reduce glucose disposal.
Visceral fat increases with estrogen loss and and increase in cortisol.
And suddenly everything feels different even though the patient tells me: “I’m eating exactly the same way I always have.” And the truth is, she probably is. But, her physiology has changed.
That’s why I don’t think the answer is simply increasing the GLP-1 dose every time the scale stops moving.
Sometimes we need to step back and ask: What else changed?
Does HRT Make GLP-1s Work Better?
This is an interesting question, and one we’re likely going to hear much more about. There are observational data suggesting women using menopausal hormone therapy may experience different weight-loss responses to GLP-1 medications.
But we don’t currently have enough evidence to say taking HRT will make your GLP-1 work better.
That’s not how I approach hormone therapy anyway.
Hormone replacement therapy should be considered based on the woman’s symptoms, medical history, risks, benefits, bone health, quality of life and individual goals—not as a weight-loss enhancer. But I absolutely think hormones and metabolism belong in the same conversation.
Testosterone Matters Too
Women have testosterone. And we need it.
Testosterone plays roles in sexual function, bone and muscle physiology, although the evidence and indications for prescribing testosterone to women are much narrower than many social-media discussions suggest.
In men, low testosterone can also contribute to decreased lean mass, increased adiposity, fatigue and impaired exercise capacity. We can extrapolate that testosterone is similarly important in women as well.
That doesn’t mean everyone on a GLP-1 needs testosterone. It means that when we’re thinking about body composition, hormonal physiology shouldn’t be ignored.
Thyroid Function Matters—but It’s Not Always the Thyroid
Another common scenario: “I can’t lose weight. It must be my thyroid.”
Sometimes it is.
Hypothyroidism can certainly affect energy, weight, bowel function and metabolism. But sometimes thyroid labs are perfectly appropriate and the bigger drivers are insulin resistance, menopause, sleep deprivation, stress, medication effects, inadequate activity or loss of muscle.
That’s why I prefer to look at the entire metabolic picture rather than blaming one hormone.
Eat Less Doesn’t Mean Eat Nothing
One of my biggest concerns with poorly managed GLP-1 therapy is chronic undernutrition.
If someone has very little appetite for months, they may unintentionally reduce intake of:
- Protein
- Iron
- B Vitamins
- Zinc
- Magnesium
- Calcium
- Essential fatty acids
- Fiber
- Electrolytes
This can eventually show up as: fatigue, weakness, hair loss, constipation, poor exercise recovery or simply feeling lousy.
If your medication makes it difficult to eat enough to nourish your body, I don’t automatically consider that a sign the medication is “working.” Sometimes it’s a sign the dose needs to be reconsidered.
Your Gut Needs Attention Too
GLP-1 medications slow gastric emptying and commonly cause gastrointestinal symptoms. Nausea, constipation, reflux, bloating and changes in bowel habits can all occur.
For someone who already has IBS, SIBO, gastroparesis or significant constipation, this deserves particular attention.
I generally want patients thinking about: hydration + electrolytes + fiber + movement + adequate food intake + bowel regularity from the beginning rather than waiting until they’re severely constipated.
In my experience, the vast majority of patients tolerate GLP-1s beautifully. Others need much more individualized dosing and GI support.
What About Bone?
This is another reason I don’t love aggressive weight loss in midlife women. Menopause already accelerates bone loss. And significant weight loss can also affect bone density, particularly when accompanied by inadequate protein, inadequate calcium/vitamin D intake and loss of muscle.
Resistance training helps here too. Muscle pulls on bone. Bone responds to load. That is one reason strength training is one of the closest things we have to a genuine longevity intervention.
For appropriate patients, I also think about vitamin D status, dietary calcium, protein intake and whether bone-density testing is indicated.
What I Like to Monitor
I don’t believe a GLP-1 follow-up should consist solely of: “Great—you lost eight pounds. See you next month.”
Depending on the patient, I’m interested in:
Strength
Are you maintaining or improving strength?
Protein intake
Are you actually eating enough?
CBC and metabolic panel
Glucose and HgA1c
Fasting insulin when appropriate
Lipids and ApoB depending on cardiovascular risk
Thyroid function
Iron/ferritin, B12, folate and vitamin D when clinically appropriate
Hormones when symptoms and life stage warrant evaluation
And again: How do you feel? That’s a clinical measurement too.
The Dose Should Serve the Patient—not the Other Way Around
This is one of the biggest differences in how I think about GLP-1 therapy. I don’t believe every patient needs to race toward the maximum dose.
If someone is steadily losing visceral fat, improving insulin resistance, eating adequately, exercising, maintaining muscle and feeling great on a lower dose, I’m not necessarily interested in increasing the medication just because the next dose exists. More isn’t automatically better.
The appropriate dose is the dose that helps accomplish the patient’s clinical goals while remaining tolerable and supporting good nutrition. For some patients that will be a standard therapeutic dose. For others, it may look different. The goal is not to win a contest for the highest dose or fastest weight loss.
The goal is metabolic improvement that you can actually sustain.
Think About What Happens After the Weight Comes Off
This may be the most important part.Eventually, the question becomes: Now what?
Some people will remain on GLP-1 therapy long-term. Some will transition to a maintenance dose. Others may eventually discontinue it.
But whatever the medication strategy becomes, the things you’ve built underneath it matter.
If you used the period of appetite control to build:
- Better food habits
- More muscle
- Better insulin sensitivity
- Regular exercise
- Improved sleep
- Better protein intake
- Healthier body composition
Then you’ve created something much more valuable than weight loss.
You’ve created metabolic resilience.
My GLP-1 Longevity Checklist
If you’re taking a GLP-1 after 40, I want you thinking about six things:
- Protein
Prioritize it at every meal. - Muscle
Resistance train at least a couple of times each week. - Micronutrients
Eating less food means food quality matters more. - Hormones
Especially during perimenopause and menopause, don’t ignore the hormonal piece of metabolic health. - Gut health
Stay ahead of constipation, nausea and motility issues. - Body composition—not just body weight
The goal is to lose excess fat while protecting muscle, bone and function.
The Bottom Line
I think GLP-1 medications are one of the most important advances we’ve had in metabolic medicine in a very long time. But the medication is only one part of the treatment. After 40, I don’t want my patients simply becoming lighter. I want them becoming: stronger, metabolically healthier, better nourished and more resilient.
Because the real goal isn’t fitting into a smaller pair of jeans.
It’s being 60, 70 and 80 years old with enough muscle to travel, hike, carry groceries, get off the floor, play with your grandchildren and continue doing the things that make your life yours. That’s what longevity means to me.
And if we’re going to use powerful medications to change metabolism, let’s use them in a way that supports that goal.
Looking for a More Comprehensive Approach to GLP-1 Therapy?
At Boulder Holistic Functional Medicine in Boulder, Colorado, we look beyond the number on the scale. Our approach to metabolic health may include GLP-1 therapy alongside evaluation of insulin resistance, hormones, nutrition, body composition, muscle preservation, gut health, sleep and other factors influencing how you feel and age.
If you’re considering GLP-1 therapy, or already taking one and want to make sure you’re protecting your muscle and metabolic health, schedule a consultation with our team.
This article is for educational purposes only and is not intended as individual medical advice. GLP-1 medications and hormone therapies are prescription treatments with potential risks, contraindications and side effects and should be used under appropriate medical supervision.
