Not Losing Weight on Semaglutide or Tirzepatide? What Body Recomposition Really Means on GLP-1 Medications 

Your injections are on track. Your eating habits have shifted. You’re more active than before. But when you check the scale, the number looks the same as it did last week. It’s frustrating, but it doesn’t always mean something is wrong. 

“Why am I not losing weight on semaglutide” and “why am I not losing weight on tirzepatide” are among the most frequently asked questions from people on these medications. In many cases, the explanation comes down to body recomposition, a shift that your scale simply isn’t designed to detect.

What Is Body Recomposition? 

So what is body recomposition? It refers to the process of losing fat while maintaining or even slightly increasing lean muscle mass. Research shows that body recomposition can happen without any change in your total body weight. 

A closer look at the biology makes this easier to grasp. Fat and muscle don’t weigh the same per unit of volume. According to research in the Journal of Biomechanics, skeletal muscle has a density of around 1.055 g/mL, while adipose tissue (body fat) falls between 0.925 and 0.970 g/mL. In practical terms, a pound of muscle occupies less physical space than a pound of fat. This means your body can undergo meaningful improvements, losing fat while holding onto muscle, without any movement on the scale. 

This concept applies broadly across weight loss methods, but it’s especially relevant for anyone using semaglutide or tirzepatide. Semaglutide mimics GLP-1, a naturally occurring hormone that regulates hunger and blood sugar. Tirzepatide works on two fronts. It activates both GLP-1 and GIP receptors, making it the first approved medication to target both pathways. GIP is active in adipose tissue and affects the way your body handles energy metabolism and fat storage. 

For those looking to encourage body recomposition while on a GLP-1, prioritizing strength training and getting enough protein can help maintain lean mass during fat loss. How long does body recomposition take? Results can begin appearing anywhere from a few weeks to several months into your journey, regardless of what the scale shows. Since tirzepatide and semaglutide operate through distinct mechanisms, knowing what sets them apart can help you set appropriate expectations for your results. 

Fat Loss vs. Weight Loss: Why It Matters 

Recognizing the distinction between fat loss and weight loss can reshape how you view your own progress. Weight loss refers to any decrease in total body mass, including fat, muscle, water, and gut contents. The scale alone cannot distinguish which of these contributed to the change. The overall goal is fat loss, especially fat stored around the organs. Losing this type of fat is linked to a lower risk of heart disease and other metabolic conditions.

Research suggests GLP-1 medications promote fat loss, with clinical studies showing these therapies reduce total body weight primarily through reductions in adipose tissue rather than lean mass. In a body composition substudy of the STEP 1 trial, participants taking semaglutide saw a 19.3% reduction in total fat mass and a 27.4% reduction in visceral fat (the dangerous fat stored around your organs). And while total lean mass decreased slightly, the proportion of lean mass relative to total body weight actually improved with treatment. 

So even when it seems like your medication isn’t producing the weight loss results you anticipated, positive changes in your body composition may already be underway. 

Does Muscle Really Weigh More Than Fat? 

You’ve probably come across the idea that muscle weighs more than fat. Strictly speaking, a pound of anything weighs a pound. The real difference is density. Muscle is more compact, so a pound of it takes up less space than a pound of fat. This is why body recomposition can change how you look and feel without changing your weight. can change how you look and feel without changing your weight. 

This tends to be particularly noticeable in the first few months of GLP-1 treatment. If you’ve started incorporating more protein into your diet or added resistance training (both are usually provider-recommended alongside GLP-1 medications), you may be preserving muscle while losing fat. The result may be a smaller waistline, better fitting clothes, and improved energy, all without the scale telling the whole story.

For those looking to preserve muscle during their GLP-1 journey, combining high-quality protein supplementation with proper nutrition may help promote fat loss while maintaining lean mass. 

How Much Weight Can You Lose on Semaglutide or Tirzepatide? 

If you’re wondering how much weight you can lose on tirzepatide or semaglutide, it can be helpful to know what the research actually found. In the STEP 1 trial, participants on semaglutide lost an average of nearly 15% of their body weight over 68 weeks. In the SURMOUNT-1 trial, tirzepatide users lost between 15 and 21% depending on dose. In the IVIM study, semaglutide patients in a telehealth program lost an average of 19.5% at 52 weeks, with 94% losing at least 10% of their body weight. These numbers are encouraging, but they’re averages. Furthermore, some people see results quickly, others start slower, and that’s completely normal. 

If your weight loss feels slow, that doesn’t mean the medication isn’t working. Hydration, hormones, and digestion can all shift the scale by several pounds from one day to the next. And if your body composition is changing, the scale might stay flat even while real progress is happening underneath. 

When It Feels Like Your GLP-1 Medication Has Stopped Working 

A possible concern that comes up several months into treatment is the feeling that your GLP-1 stopped working. You were losing weight steadily and then progress slowed or stopped entirely. 

Before concluding that the medication isn’t effective anymore, consider a few possibilities: 

Your body may have reached a temporary weight loss plateau. This is a normal part of the process, whether you’re on semaglutide or tirzepatide. As you lose weight, your metabolism can adapt, causing a change to your body’s caloric needs. This doesn’t mean the medication has failed. It means your body is adjusting. 

Something else to keep in mind: you might be experiencing body recomposition without realizing it. If you’ve added physical activity or increased protein intake, you could be building muscle while continuing to lose fat.  

It’s also possible that a dose adjustment is needed. GLP-1 medications follow a dosing schedule, starting at lower doses and gradually increasing. If you’ve been on the same dose for a while and progress has stalled, it may be time to discuss when to increase your GLP-1 dose with your healthcare provider. Understanding GLP-1 dosing can help you navigate this conversation. 

Signs You’re Making Progress Beyond the Scale 

If you find yourself not losing weight on tirzepatide or semaglutide but wondering whether things are still working, look beyond the scale. Some non-scale indicators of progress include: 

• Changes in how clothes fit: Pants feeling looser or dropping a size can signal you’re losing inches, even if the scale hasn’t moved. 

• Improved energy levels: Feeling more energetic and less sluggish as you lose fat. 

• Better sleep quality: Weight loss and reduced inflammation may contribute to improved sleep. 

• Visible changes: Fat loss often shows up in your face, arms, or midsection before the scale catches up. 
• Improved lab markers: Better blood sugar, cholesterol, or blood pressure numbers are meaningful wins the scale doesn’t capture. 
• Reduced hunger and food noise: Thinking about food less and feeling satisfied with smaller portions means the medication is doing its job. Thinking about food less and feeling satisfied with smaller portions means the medication is doing its job. 

When to Check In With Your Provider

Body recomposition may be the explanation in many cases where the scale stays put, but there are times when it makes sense to touch base with your care team. 

If the scale hasn’t changed and you’re feeling stuck, it can also be a sign that certain lifestyle factors need more support. Sleep quality, stress levels, nutrition, movement, and daily routines all play an important role in how your body responds to GLP-1 therapy. This isn’t about doing anything “wrong.” Many of these areas are challenging, especially during busy or stressful seasons of life.  

Checking in with your provider can open the door to additional guidance, including support from our functional health coaching team, who can help you identify and work through barriers in a personalized, sustainable way. 

Setting Realistic GLP-1 Weight Loss Expectations 

Managing expectations is part of a sustainable GLP-1 weight loss journey. These medications are highly effective for many people, but they’re not magic, and the path isn’t always linear. 

Weight loss happens in phases. Early losses often include water weight, which can come off quickly, while fat loss happens more gradually. And if you’re building healthy habits like strength training and eating adequate protein, you may experience periods where your body composition is improving even though the scale isn’t moving. 

Combining GLP-1 treatment with diet and exercise creates a foundation for long-term success. The goal isn’t just a number on the scale. It’s improved health, sustainable habits, and a body composition that supports your long-term well-being. improved health, sustainable habits, and a body composition that supports your long-term well-being. 

So if you’re feeling frustrated because the scale isn’t budging, take a step back. Measure your waist, notice how your clothes fit, and pay attention to your energy and hunger levels. Progress isn’t always measured in pounds, and sometimes your body is changing in ways the scale simply can’t capture. 

Medically reviewed by Courtney Floyd, MD, Physician at Ivím Health 

Disclaimer:  

Compounded Medications: Compounded semaglutide and compounded tirzepatide are not FDA-approved. Compounded drugs have not been reviewed by the FDA for safety, efficacy, or manufacturing quality. The FDA does not verify the safety, effectiveness, or quality of compounded drugs. 

Prescription Medications: Prescription provided only if clinically appropriate. All prescriptions are at the sole discretion of licensed healthcare providers based on individual patient evaluation. 

Individual Results: Individual results may vary. Weight loss outcomes depend on medication adherence, lifestyle factors, and individual response. Consult your healthcare provider before making any medication changes. 

Medical Advice: This content is for informational purposes only and does not constitute medical advice. Always consult with a licensed healthcare provider regarding your health needs, diagnosis, and medication management. 

Trademarks: Wegovy® and Ozempic® are registered trademarks of Novo Nordisk A/S. Mounjaro® and Zepbound® are registered trademarks of Eli Lilly and Company. Ivím Health is not affiliated with, endorsed by, or sponsored by these manufacturers.

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