GLP-1 medications are everywhere right now.

You’ve likely seen the headlines, the before-and-after photos, and the stories of rapid weight loss. And if you’re a woman over 40 who’s struggled to lose weight despite “doing everything right,” it makes sense that these medications have caught your attention.

Curiosity isn’t the problem. It’s often the first sign of someone looking for a solution that finally works.

Before making any decision, though, it’s worth understanding what GLP-1 medications actually do in the body — and what they don’t.

What GLP-1 Medications Are Designed to Do

GLP-1 receptor agonists work by reducing appetite, slowing gastric emptying, and improving insulin signaling. These mechanisms are exactly why many people experience meaningful weight loss.
Eating less feels easier. Hunger cues quiet down. Portions naturally shrink.
From a physiological standpoint, that makes sense.
But appetite suppression and weight loss are only part of the picture.

Weight Loss vs. What Changes Inside the Body

One of the most under-discussed aspects of GLP-1–associated weight loss is body composition — what type of tissue is being lost as the scale goes down.

Clinical trials consistently show that during rapid weight loss, approximately 20–40% of total weight lost can come from lean mass. Lean mass includes muscle, connective tissue, and other non-fat components of the body.

Not all lean mass is muscle — but muscle makes up a substantial portion of it.

This pattern is not unique to GLP-1 medications. Similar proportions of lean mass loss are seen with bariatric surgery and very low-calorie diets. What matters most is how the body is supported during weight loss.

Why Muscle Matters — Especially for Women after 40

Muscle isn’t just about strength or appearance.

It plays a central role in:

Metabolic rate and energy expenditure
Blood sugar regulation
Insulin sensitivity
Physical resilience and mobility
Long-term weight maintenance

As women move through perimenopause and menopause, muscle loss accelerates naturally due to hormonal shifts — particularly declining estrogen and testosterone.

When rapid weight loss is layered on top of this transition without adequate support, the risk of losing metabolically protective muscle tissue increases.

An Important Nuance: Muscle Quality vs. Muscle Quantity

Here’s where the conversation becomes more balanced.

Emerging research shows that although absolute muscle volume may decrease during GLP-1 therapy, muscle quality often improves.

MRI-based studies demonstrate reductions in intramuscular fat, improved insulin sensitivity, and enhanced metabolic efficiency of remaining muscle tissue. Functional measures such as handgrip strength frequently remain stable or even improve.

This means muscle loss does not automatically equal weakness or metabolic decline.

However, these benefits are most consistently seen when weight loss is paired with appropriate lifestyle support.

Who Should Pay Extra Attention

Certain populations are more vulnerable to clinically meaningful muscle loss during rapid weight reduction, including:
Women over 40
Perimenopausal and postmenopausal women
Adults over 65
Individuals losing weight very rapidly
Those with low protein intake
Those not engaging in resistance training
For these groups, preserving muscle is not optional — it’s foundational to long-term health.

What the Evidence Consistently Shows

Across clinical trials and consensus guidelines, one message is clear:

GLP-1 medications change appetite. They do not automatically protect muscle.

Muscle preservation depends on:

Structured resistance training
Adequate protein intake (often ≥1.3 g/kg/day)
Monitoring of strength and function — not just scale weight

This is where outcomes begin to diverge.

The same medication can lead to very different long-term results depending on how the body is supported during weight loss.

Before You Decide

This isn’t about being for or against GLP-1 medications.

It’s about understanding that weight loss alone is not the same as metabolic health — especially in midlife.

If GLP-1s are on your radar, the most important step isn’t rushing into a decision. It’s learning how to protect strength, metabolism, and long-term function if weight loss occurs.

Curiosity is smart.
Informed decisions are smarter.

Disclaimer
This post is for educational purposes only and is not intended as a substitute for professional medical or mental health advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or mental health concerns.

Author
Dianne Bly, Functional Health & Nutrition Consultant, RN, BSN, PN1 Nutrition, CFMP

References

Mozaffarian D, Agarwal M, Aggarwal M, et al. Nutritional Priorities to Support GLP-1 Therapy for Obesity. American Journal of Clinical Nutrition. 2025;122(1):344–367.
Karakasis P, Patoulias D, Fragakis N, Mantzoros CS. Effect of GLP-1 Receptor Agonists and Co-Agonists on Body Composition. Metabolism. 2025;164:156113.
Anyiam O, Ardavani A, Rashid RSA, et al. Effects of GLP-1 Receptor Agonists on Measures of Muscle Mass. Obesity Reviews. 2025;26(7):e13916.
Neeland IJ, Linge J, Birkenfeld AL. Changes in Lean Body Mass With GLP-1-Based Therapies. Diabetes, Obesity & Metabolism. 2024;26(Suppl 4):16–27.
Gonzalez-Rellan MJ, Drucker DJ. New Molecules and Indications for GLP-1 Medicines. JAMA. 2025.