GLP-1 Muscle Loss Calculator
See how much muscle you could lose on Ozempic, Wegovy, Mounjaro, or Zepbound. Get one simple, clear thing you can do about it.
Lean mass retention calculator
Muscle Loss Calculator
Enter your details to get instant results below
Your results
High risk
You're likely losing a meaningful amount of muscle.
Muscle Preservation Score
48/100
The dot shows where your score of 48 falls on the scale above.
Muscle you could lose in the next 3 months
1.5 lbs
Protein target each day
131g
You're 41g short of this today
What to do next
Increase daily protein by about 41g to reach your target. This is your single biggest lever for protecting your muscle right now.
This is an educational estimate based on published research. Always talk to your doctor before changing your medication, diet, or exercise routine.
Why muscle matters on GLP-1 medications
Ozempic and Wegovy both use a medicine called semaglutide. Mounjaro and Zepbound both use a medicine called tirzepatide. All four work by lowering your appetite, which helps you eat less and lose weight. But losing weight is different from losing fat. Doctors have used detailed body scans called DEXA scans to study people taking these medications. Some studies found that a quarter to nearly half of the weight people lost was muscle, organs, or the tissue that supports bone, not fat.
Your muscle does more than help you look toned. It's where your body uses up a lot of your blood sugar. It keeps your resting metabolism higher. Losing too much of it can slow your metabolism, make you weaker, and make everyday things like carrying groceries or climbing stairs harder, especially as you get older. It can also make it easier to regain fat weight after you stop treatment. Some people call this pattern “skinny fat.”
Here's the good news. You can protect your muscle while you lose weight. Two things make the biggest difference. Eating enough protein. Doing regular resistance training. Both are linked to better muscle retention in people losing weight, including people on GLP-1 medications. This calculator shows you how your current habits measure up and gives you one clear thing to work on next.
Protecting your muscle on a budget
Most advice about protecting your muscle assumes you can afford a gym membership and a cart full of chicken breast and protein powder. That isn't realistic for everyone. Your budget shouldn't decide whether you get to protect your muscle. Here are ways to do both without spending much.
Budget friendly protein
- Eggs. A dozen eggs gives you about 72 grams of protein for just a few dollars.
- Canned tuna and canned chicken. They last a long time and add 20 grams of protein or more to a meal in seconds.
- Dried beans, lentils, and chickpeas. Some of the cheapest protein per gram anywhere. Canned versions cost a little more but save time.
- Cottage cheese and plain yogurt. A lot of protein for the price, and they work as a snack or breakfast.
- Peanut butter. Cheap, shelf stable, and easy to add to almost any meal.
- Chicken thighs. Usually cost less than chicken breast and carry just as much protein.
- Powdered milk and whey protein powder. Often cheaper per gram of protein than fresh meat, especially bought in bulk.
Strength training without a gym
- Push ups. Build your chest, shoulders, and arms. Start against a wall or counter if a full push up is too hard.
- Bodyweight squats and lunges. Build your legs and glutes, some of the biggest muscles in your body.
- Planks and glute bridges. Build your core and lower back.
- Stairs. Free strength training. Walking up them works your legs the same way a gym machine would.
- A resistance band. Costs about the price of a fast food meal and adds resistance to almost any exercise.
- Filled water jugs or a loaded backpack. Stand in for dumbbells when you need extra weight.
- Free workout videos online. Can walk you through a full bodyweight routine if you're not sure where to start.
You don't need a lot of money to protect your muscle. You need consistency, and there are ways to be consistent no matter your budget.
Advice for older adults taking GLP-1 medications
Most advice about muscle loss on GLP-1 medications is written for younger and middle aged people trying to lose weight. If you're older, your risk looks different, and so does what's at stake.
As you age, you naturally lose some muscle every year, even without any medication. Doctors call this sarcopenia. If you start a GLP-1 medication on top of that, the muscle loss from the medication adds to muscle loss you're already experiencing. Together, they can add up to more than either one on its own.
For a younger person, losing muscle mostly changes how they look and how their metabolism works. For an older adult, it can mean something more serious. Less muscle can mean a higher chance of falling. It can mean less strength to get up from a chair, carry groceries, or catch yourself if you trip. It can mean losing the independence to live on your own.
Here's the good news. The same two things that protect anyone's muscle work especially well for older adults. Resistance training builds and protects muscle at any age, and research shows older adults respond to it just as well as younger people do. Eating enough protein matters just as much, and often more, since appetite and protein intake both tend to drop with age even before a GLP-1 medication is added.
If you're older and starting a GLP-1 medication, a few things are worth doing.
- Talk to your doctor about your muscle and bone health before you start, not only your weight.
- Ask whether a baseline strength or balance check makes sense for you.
- Consider working with a physical therapist or trainer who has experience with older adults if resistance training is new to you.
- Bring up your pace of weight loss with your prescriber. Slower, steadier loss tends to be easier on your body at any age, and especially as you get older.
Frequently asked questions
Why do GLP-1 medications cause muscle loss?
GLP-1 medications lower your appetite. When you eat less, you often eat less protein too. When your body is short on calories, it breaks down some muscle along with fat. Eating enough protein and doing resistance training can tell your body to hold onto that muscle instead. Losing weight quickly can make muscle loss worse than losing weight slowly through diet alone.
How much muscle can I lose on Ozempic, Wegovy, Mounjaro, or Zepbound?
Studies using DEXA scans suggest muscle can make up about 25 to 40% of the total weight lost on these medications if you don't take steps to protect it. For comparison, muscle usually makes up about 20 to 25% of weight lost through diet alone. Your own results depend on your age, your starting body composition, how much protein you eat, and how active you are.
Can I prevent muscle loss while on a GLP-1?
Yes, you can protect a lot of it. The two things backed by the most evidence are eating enough protein and doing regular resistance training. Aim for about 1.6 grams of protein per kilogram of body weight each day. Aim for 2 to 3 resistance training sessions per week.
How much protein do I need while taking a GLP-1 medication?
A common target is about 1.6 grams of protein per kilogram of body weight each day. That's higher than typical general guidelines, and it helps protect your muscle while you're eating less overall. If you train hard, some doctors and dietitians recommend as much as 2 to 2.2 grams per kilogram.
Does resistance training really make a difference?
Yes. Lifting weights signals your body to build and keep muscle, even while you're losing weight. Studies on weight loss consistently show that people who strength train lose less muscle than people who only do cardio or don't exercise at all.
What's a "Muscle Preservation Score" and how is it calculated?
It's a score from 0 to 100. We build it from how often you do resistance training, how close your protein intake is to your target, and how fast you're losing weight. We layer that on top of published rates of muscle loss for people on GLP-1 medications. A higher score means your current habits are doing a better job protecting your muscle. Think of it as an educational estimate you can use to guide your choices.
Is losing weight too fast bad for my muscles?
Generally, yes. Losing weight faster tends to mean losing more muscle, no matter what method you use. Many doctors consider losing about 0.5 to 1% of your body weight per week a reasonable pace. If you're consistently losing weight faster than that, it may be worth talking to your prescriber about slowing down.
My weight has stalled. Does that mean the medication stopped working?
This is one of the most common worries people run into, and it makes sense why. The scale gets all the attention. Here's what's likely happening. If you're eating enough protein and doing resistance training, you might be losing fat and holding onto or even building muscle at the same time. Muscle is denser than fat, so your body can improve even while the number on the scale barely moves. Try tracking how your clothes fit or taking progress photos alongside the scale. Give it a few more weeks before assuming the medication has stopped working.
Should I get a DEXA scan or InBody test to check my body composition?
If you can get one, a DEXA scan is the most accurate way to track how your fat and muscle change over time. It gives you a much clearer picture than any calculator can. Think of this tool as something to use between scans, to help you understand your risk and stay on track.
Can GLP-1 medications affect my bones too?
Yes, and this doesn't get talked about enough. Rapid weight loss, including the weight loss from GLP-1 medications, can lower bone density along with muscle. This risk is higher for older adults and for women who have gone through menopause. The same things that protect your muscle also help protect your bones. Resistance training puts healthy stress on your bones. Enough protein and calcium give your body what it needs to maintain them. If you're in a higher risk group, it's worth asking your doctor whether a bone density scan makes sense for you.
Does Mounjaro or Zepbound cause more muscle loss than Ozempic or Wegovy?
We don't have much direct research comparing the two side by side yet. Mounjaro and Zepbound tend to produce more total weight loss on average. That can mean more total muscle lost overall, even if the share of muscle lost is similar. This calculator makes a small adjustment for that. Your own results will still depend on your habits.
What happens to my muscle if I stop taking my medication?
It's completely normal to worry about this. Many people do gain some weight back after they stop a GLP-1 medication. If you lost muscle along the way and didn't do much to protect it, your metabolism may be a little weaker than before you started, which can make it easier to regain fat. The best time to protect yourself is now, while you're still on the medication. Keep your protein up and keep training so you carry as much muscle as possible into whatever comes next. Talk to your prescriber about a plan for stopping or tapering your dose when the time comes.
Is this calculator a substitute for medical advice?
No. This tool gives you an educational estimate based on published research. Your prescriber or a registered dietitian knows your full medical history, labs, and body composition, and can give you advice suited to you. Talk with them before changing your medication, diet, or exercise routine.