The Scale Is Going Down… But Are You Losing Fat or Muscle?

Posted: September 24, 2026

GLP-1 medications have changed weight management for many people. If you’ve struggled to lose weight in the past, seeing the number on the scale finally move down can feel like a huge win.

But the scale doesn’t answer one important question: Are you losing mostly body fat, or are you losing muscle, too?

What Exactly Are You Losing?

When the scale goes down, weight loss can come from several sources:

• Body fat
• Muscle
• Water
• Glycogen stores

Ideally, most of the weight lost should come from body fat while preserving as much muscle as possible.

This is important because muscle plays a major role in metabolism, strength, mobility, and long-term weight maintenance.

Weight Loss Isn’t Always Fat Loss

Two people can lose the same amount of weight but have very different outcomes.

Same Weight Loss. Different Results.

Patient A:

30 pounds lost = 25 pounds fat + 5 pounds muscle

Patient B:

• 30 pounds lost = 15 pounds fat + 15 pounds muscle

On the scale, both people appear equally successful.

Patient A is more likely to maintain strength, support healthy metabolism, and sustain their results over time, while Patient B may experience more fatigue, decreased strength, and greater difficulty maintaining weight loss.

Research supports this concern. In the STEP 1 body composition sub-study, participants taking semaglutide lost significant amounts of body fat, but some lean mass was lost as well. [academic.oup.com], [pmc.ncbi.nlm.nih.gov]

The goal isn’t simply to lose weight. The goal is for you to lose body fat while maintaining as much muscle as possible.

Why Patients Taking GLP-1 Medications May Be at Higher Risk

One reason GLP-1 medications work so well is that they reduce appetite and increase feelings of fullness. Many of Your Wellness Center patients have reported this directly to our dietitian. While this helps create a calorie deficit, she advises that it can also make it harder to meet nutrition needs.

• Eating significantly less food
• Skipping meals
• Struggling to meet protein needs
• Difficulty consuming enough calories to support muscle maintenance

When the body doesn’t receive enough nutrition, especially protein, it may break down muscle tissue along with body fat. This is something you don’t want to continue while taking this medication.

Why Muscle Matters

Many people think muscle is only important for athletes. Muscle helps people with:

• Supporting metabolism
• Maintaining strength and physical function
• Improving balance and mobility
• Support healthy aging
• Preserve independence and quality of life

When muscle mass declines, everyday tasks can become more difficult, energy levels may drop, and maintaining weight loss may become more challenging. While taking a GLP-1, energy levels tend to decline as a side effect of the medication; it’s important to work even harder to maintain muscle to stay energized.

Signs You May Be Losing Muscle

The scale cannot tell you whether you’re losing fat or muscle.

Potential signs of muscle loss include:

• Feeling weaker during workouts
• Difficulty carrying groceries or performing daily tasks
• Increased fatigue
• Reduced strength or endurance
• Rapid weight loss
• Looking smaller without feeling stronger

These signs don’t automatically mean you’re losing muscle, but they’re worth discussing with our registered dietitian.

Look Beyond the Scale

Rather than judging progress solely by pounds lost, consider other measures of success:

• Strength: Are you maintaining or improving it?
• Physical Function: Do daily activities feel easier?
• Measurements: Are your waist or hip measurements changing?
• Body Composition: InBody or DEXA scans can provide additional insight.
• How You Feel: Better energy, mobility, sleep, and confidence all matter.

Three Ways to Protect Muscle During Weight Loss

1. Prioritize Protein

Protein is one of the most important nutrients for preserving muscle during weight loss.

Because appetite often decreases on GLP-1 medications, it’s important to intentionally include protein throughout the day.

Examples include:

• Lean poultry
• Fish
• Eggs
• Greek yogurt
• Cottage cheese
• Soy foods
• Beans and legumes
• Protein supplements when appropriate

2. Include Strength Training

Walking is excellent for cardiovascular health, but resistance training helps signal your body to maintain muscle.

Options include:

• Weight training
• Resistance bands
• Bodyweight exercises
• Functional strength activities

Even two to three sessions per week can make a meaningful difference.

3. Avoid the “Eat as Little as Possible” Mindset

Many people assume that because they’re less hungry, they should eat as little as possible.

In reality, eating too little can increase the risk of nutrient deficiencies, fatigue, and muscle loss.

The goal isn’t simply eating less. The goal is to create a sustainable calorie deficit while providing your body with the nutrients it needs.

The Bottom Line

GLP-1 medications can be powerful tools for weight management, but the quality of the weight you lose matters as much as the quantity.

If the scale is going down, that’s only part of the story.

The best outcomes happen when patients lose body fat while preserving the muscle that supports metabolism, strength, and overall health.

Don’t focus solely on losing weight. Focus on losing fat while protecting the muscle that helps you stay strong, active, and healthy for years to come.

Long-term success isn’t just about a smaller number on the scale. It’s about building a healthier, stronger body along the way. Our dietitian, Alyssa, is our best resource for nutrition and GLP-1 diet guidance. Call Your Wellness Center to schedule an appointment with her.

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