The Impact of GLP-1 Medications on Weight Loss and Muscle Mass

Summary 

In this episode, Ed Delesky, MD, and Nicole Aruffo, RN, discuss the impact of GLP-1 medications on lean body mass and muscle mass during weight loss. They explore definitions of lean body mass and skeletal muscle mass, the effects of weight loss medications on muscle physiology, and strategies to preserve muscle mass through diet and exercise. The conversation emphasizes the importance of understanding muscle quality and the potential risks of sarcopenia, particularly in vulnerable populations. The episode concludes with practical advice for maintaining muscle health while using weight loss medications.

Takeaways

GLP-1 medications can impact muscle mass during weight loss.
Lean body mass includes all tissues except fat.
Skeletal muscle mass is crucial for strength and metabolism.
Different studies show varying impacts of GLP-1 on muscle mass.
Weight loss can lead to reduced resting energy expenditure.
Muscle quality is an important factor in health outcomes.
Sarcopenia may be concern for older adults on weight loss medications.
Increasing protein intake can help preserve muscle mass.
Resistance training is essential for maintaining muscle strength.
Consult your doctor for personalized dietary and exercise advice.

Keywords

weight loss, GLP-1 medications, muscle mass, lean body mass, obesity, health, nutrition, exercise, patient education, diabetes, zepbound, wegovy, ozempic, mounjaro

Chapters

• 0:00 Introduction and Social Notes
• 7:41 Exploring Weight Loss Medications
• 9:39 Understanding Lean Mass vs Skeletal Muscle
• 13:40 Muscle Physiology and Weight Loss
• 17:15 Strategies to Preserve Muscle Mass
• 21:14 Conclusion and Key Takeaways

Transcript

Ed Delesky, MD (00:00)
Hi, welcome to your checkup. are the Patient Education Podcast, where we bring conversations from the doctor's office to your ears. On this podcast, we try to bring medicine closer to its patients. I'm Ed Delesky a family medicine resident in the Philadelphia area.

Nicole Aruffo, RN (00:14)
I'm Nicole Aruffo, I'm a nurse.

Ed Delesky, MD (00:16)
And we are so excited you were able to join us here again today. So we've been having a really fun morning, lots of hee hee ha ha moments. And I've got a couple notes from this week. These notes are, let's see. We enjoyed a everything bagel with lox, capers, cream cheese, a mustard garlic aioli on an artisan everything bagel. How did you find that when you enjoyed it?

Nicole Aruffo, RN (00:43)
that's like my favorite thing. So I loved it.

Ed Delesky, MD (00:45)
That's excellent. The next item is. Well, I found it because I thought it was excellent and delicious and I thought this is absolutely something that I want to eat today. And while I was actually like moody that day and so I decided while I was walking around. I did that there's. man, so I was in Trader Joe's and like, let me get the accoutrements for for this. I just there's this cloud over me that that day, singular day.

Nicole Aruffo, RN (00:49)
Where do you find it?

Eddie had his man period. He a bagel. We've all been there.

Ed Delesky, MD (01:16)
And maybe a little bit in the next one, but it lifted and it was great. thereafter, our content of interest this week has been Temptation Island. What do you think about Temptation Island?

Nicole Aruffo, RN (01:29)
my God, it was so good. So messy within the first like five minutes of the show. So it's based on like four couples. Every single couple is a huge red flag, mainly the guys, because those men were all trash. So, you know, that's like gearing up for quality TV. And it was, it didn't disappoint.

Ed Delesky, MD (01:50)
It didn't at all.

Mark Wahlberg was a key piece to this entire experience and definitely not the Mark Wahlberg you're thinking of. But this man deserves more time in the spotlight. Ten episodes on Netflix. And then also he was like, I've been doing this for a long time. The guy talks to them like he's a therapist. And we're like, wait, you've been doing this for a long time. This is the first episode on the first season on Netflix. But there are more seasons elsewhere. Not exactly sure where.

Nicole Aruffo, RN (02:17)
I think I'm peacock.

but don't quote me on that. I haven't watched them.

Ed Delesky, MD (02:21)
And then yesterday we were able to go on a day dump date. We went to one of our favorite places. Simply put the name Tommy D's not just kidding. It's Tom's dim sum. Tell us about your perspective.

Nicole Aruffo, RN (02:35)
I just love this place. Well, one, the dumplings are really good and the cold nudes. Those are the two things that we always go there for. But more importantly, it's the atmosphere and the straight to the point customer service. I love it. It's minimal interaction. They like strictly mean business. Like you go there, tell them how many people they're like two there and they point to a table and you go sit down and then they

give you water, they practically throw the menus at you, run away, and then they come back. And like, they don't ask you if you're ready to order, like you have to be ready when they come back and they're like, they come back, they're ready to take the order. They take it. And then like, then the food comes out and they practically just like toss it on the table and run away. Yeah. Like they don't like talk to you. There's no introduction. Have you been here before? Not straight to the point. They don't come back.

like five times after you've just taken a big bite of food to ask how everything tastes because they know everything's good. They don't need to follow up on.

Ed Delesky, MD (03:40)
on

it. They just completely omit the interaction.

Nicole Aruffo, RN (03:43)
And then they, you know, take away your place. They don't ask you if you're done or if you need to order anything else. They just bring you the bill and then you pay and like they take it real quick. Sometimes stand there until you whip the card out and keep it moving. Yeah, it's they have an efficient operation over there.

Ed Delesky, MD (04:02)
Yeah, they certainly do. Amazing place. I have three notes from my experience yesterday. We were placing our order and I practically wasn't ready. I knew we were getting the crab meat, pork, soup, dumplings. I think that that isn't even the exact name. Two orders of those, two orders of cold nudes. And I think an eternity passed by with her laser eyes pointing into me as I am looking at this menu.

And my mind is oscillating back and forth between look at the items and pick faster. And I will not be rushed as I am going to give them my money. I refuse to be rushed. And she's standing there. She's looking at me. She's looking over her shoulder. Pretty sure she checked her watch three times and she's

Nicole Aruffo, RN (04:49)
really throwing a wrench in there. Operation.

Ed Delesky, MD (04:52)
I was. Actually, it's four notes. So that was one of the experiences. There were people sitting by the window. They got there after us or maybe like they got there before us. Sitting and one of them, obviously, this place is an Asian restaurant, Asian cuisine, and this woman asks, well, is there any MSG in here? There's more MSG in there than Madison Square Garden. Like I of course, there's MSG in this food. If you couldn't feel it when you're like.

Nicole Aruffo, RN (05:01)
They were already there.

Ed Delesky, MD (05:20)
pulsing through your veins as you're walking out of the restaurant. Like I felt like I had had drinks when I left that place. But we also worked out a lot. We were a little low on. Low on the blood pressure. The next thing I had to say is that there was this couple that sat next to us, a little bit older than us. And, you know, we had separate dining experiences because I guess technically the tables weren't together, but they were about three inches apart. And I have to say.

Nicole Aruffo, RN (05:29)
You're a little hypotensive.

Their table was like three inches from ours.

Ed Delesky, MD (05:50)
Yeah. And, you know, we're having a conversation when there's a party next to us. Our conversation tends to like change a little bit. Like I'll make like a little bit more of a freaky comment. Like I talked about taking the potato to the head from potato gun just to kind of see what their reaction was. But it felt like it was almost a shared dining experience. So I think there need to be at least six inches between like one table and another before considering that they're separate tables.

Nicole Aruffo, RN (06:18)
Yeah,

everywhere else except for Tom's Dim Sum.

Ed Delesky, MD (06:21)
Sure. I'll take it from them. I did lock eyes with that woman once and I was one breath away from being like, well, we're basically eating together anyway. But I did it and I held back, which was good. And I felt good about that. My fourth and final note on Tom's dim sum is that robot. And normally selective hearing lots of earwax, but I can hear that robot coming from a mile away. And it's just this little this little sound like I don't even I can't even do it.

Nicole Aruffo, RN (06:47)
little

Ed Delesky, MD (06:48)
It's

a little jingle and you got to go. But it's this robot that delivers the food out and it's a part of the staff. And I like it comes and then it recedes back into darkness. And it's probably the beginning of an A.I. Long. It was there long before A.I. was a thing. And I love that robot. I love Tom's dim sum. You should probably go.

Nicole Aruffo, RN (07:10)
And he was like facing away from the robot. And literally he heard like the first tone of the jingle and he's his like ears perked up and he was like, the robots coming. He said the robots coming before I could even see the robot. He loves it so much.

Ed Delesky, MD (07:26)
I

love the robot. All right, so lots of fun, important things that happened this weekend, but why don't we give the people what they came for? So what are we going to talk about today? Nick.

Nicole Aruffo, RN (07:41)
So today we're circling back to the weight loss medications, but today we're specifically talking about our lean muscle mass, what happens to our muscle when we're taking a GLP-1.

Ed Delesky, MD (07:54)
You bet. So this is a really common question that happens and comes up when people are on a GLP-1 or GLP-GIP medication. What happens to my muscle mass? And by those medicines, we are talking about semaglutide and tirzepatide otherwise known as Wegovy or ZepBound are the medications used for weight loss.

As we've talked about in the past, these medications are increasingly used for treatment of obesity. And really we're getting places where sometimes only people who underwent bariatric surgery went. But there remains a question about with significant weight loss, what is the concern and potential side effect of muscle mass quantity? Like how much there is and how does this impact health and function?

and especially for vulnerable patients. And so today, in what's a really common question that isn't really well answered, we are going to take some time and explore some evidence that's out there. This episode is based on a review article that was published in Diabetes and Obesity and Metabolism in 2024. The title of the article is Changes in Lean Body Mass with

glucagon like peptide one based therapies and mitigation strategies authored by Neeland MD and Lynch PhD and Birkenfield MD. It was published in June of 2024. And so that is what we will be using as our source material today if you wanted to go look at that article and read it yourself. But without further ado, today we're hoping to educate you about this topic.

Nikki, let's lay the groundwork and understand definitions and define our terms, lean body mass and skeletal muscle mass. Can you take us through those?

Nicole Aruffo, RN (09:51)
Yes.

lean body mass is the weight of all of our tissues and fluids, everything inside of our body except for fat. So that's our muscle organs, bone fluids and water and the fat tissue, but not our actual fat tissue. And it's calculated by doing the total body weight minus body fat weight, which there are ways to do each of

Ed Delesky, MD (10:17)
it's important to know about lean body mass because it's often used as a surrogate for muscle mass when it comes to measuring these things in trials about weight loss. And so it's really commonly assessed using something called a DEXA, which is a DEXA scan is more commonly used in like osteoporosis screening, but it's called dual energy X-ray absorbent geometry, which is what DEXA scans stands for.

A healthy range of lean body mass is somewhere between 70 % and 90 % of total body weight. And there some variations between men and women.

So this differs from skeletal muscle mass, which is the actual mass of the muscles in the body. And this is incredibly important for things like strength, function, mobility, and metabolic rate, or the rate at which your body burns calories and energy. And it turns out that this is a really challenging thing to study in studies because, or a challenging thing to measure in studies. And very few weight loss studies are actually able to

accurately measure the muscle mass directly, which is why we have to use a proxy measurement of lean body mass.

So it's important to make a distinction between the two because as you may have guessed, a change in lean mass really may not always reflect a change in muscle mass because it includes other things like water, organ weight, and

And so it's important to realize that these two terms are distinct and different from each other.

Nicole Aruffo, RN (11:52)
So going back to lean mass with the GLP-1s, what are these studies showing?

Ed Delesky, MD (12:00)
So unfortunately for the sake of making an easy answer out of this, it shows a lot of different answers. Some studies, and we're going to go through each of them, some studies report a lean mass loss of about 40 to 60 % of the total weight that was lost. But other studies show a lean mass reduction of about 15 % or less of the total body weight loss. So different trials go through the

semaglutide trials or otherwise called step one, which looked at the like Wegovy and Ozempic type medications.

Lean mass was responsible for about 45 % of the total body weight loss. So adipose tissue or fat was 55%. In the Surmount trial that looked at tirzepatide or ZepBound and Mounjaro lean mass was responsible for about 26%.

of the total body weight loss. And there were other studies that showed the proportion of total body weight loss that was because of lean mass loss was about 15 % or less. And so why are these answers so different? Well, there's differences between each medication. There's differences in the doses, how long these studies ran for, how they measured these things, and the people they were treating, whether they did or didn't have diabetes. And

Were they doing lifestyle interventions or were they not? So with that, there's a lot of different answers that could be there, which make it a little bit challenging to answer.

Nicole Aruffo, RN (13:40)
tell us about muscle physiology in obesity and then adaptive and maladaptive muscle changes.

Ed Delesky, MD (13:49)
Yeah. So there's, when it comes to maladaptive and adaptive muscle changes, that kind of gets at the, your muscles sink or swim in certain situations of stress and weight loss. But to speak on muscle physiology and obesity and weight loss, people who have obesity often actually have more muscle mass than people who have a normal weight. And what has been studied is that weight loss from any method.

People were losing weight before these GLP medications as typically associated with some muscle mass loss. And what that does is that a loss of muscle contributes to a reduced resting energy expenditure, which is that reduced basal metabolic rate. And that is what can make a part of the problem, which can make weight regain more likely. So if you lose more muscle, then it's harder to keep off the weight because

Muscle burns fat and calories more than other tissues. So what is there to say about this adaptive muscle response? Do your muscles come back in a way, or do they respond to weight loss in a way that's actually beneficial? So more evidence has come out suggesting with MRI studies that skeletal muscle changes with GLP medications can actually be beneficial,

They do show that maybe there are reductions in muscle volume and it appears that they might be in line with what people are expecting with aging or disease status and the amount of weight lost. But with weight loss comes an improvement in insulin sensitivity. So you're using a certain amount of insulin and how well are you using that insulin? And this concept of reduced muscle fat infiltration likely contributes to

an improved process or an adaptive process and improved muscle quality. So that's the first time we're introducing a concept of muscle quality.

Not all muscles are created equal, it seems, and you may have more muscle, but that muscle may have fat that's inside of it because that's a process of obesity. It's called ectopic adipose distribution. There can be fat in your liver. There can be fat around your heart. There can be fat in your muscle. And so this concept suggests that with weight loss, including weight loss with the GLP medications, may lead to an improved quality of muscle.

even if there isn't as much This may lower the risk of losing strength and function despite some reduction in muscle mass.

That is opposed to the idea of sarcopenia, which is a maladaptive muscle loss. So this ends up being a feared complication of significant muscle loss, strength and function. It happens to be more prevalent in older adults and those with chronic conditions. And symptoms of this can include weakness, fatigue, problems with balance, increasing falls, difficulty with mobility.

People can have more fractures and overall a reduced quality of life. And so there is some concern that people of older age who have severe disease may be more susceptible to maladaptive muscle loss with GLP-1 therapies.

So some of this counseling has become a part of my daily counseling to people who are on these medications. Nikki, what can people do to stave off the effects of losing bad muscle, losing muscle or having their muscle lose quality? Because we're realizing now that there is a concept of muscle quality and avoiding something called myosteatosis or fat infiltration in the muscle.

Nicole Aruffo, RN (17:42)
There are some dietary modifications you could make, namely increasing your protein intake, which regardless of whether you're on a GLP or not and you're just like trying to lose weight, that's something that could be helpful. Because like you said, with any kind of like major, I guess really any weight loss, there's always kind of like the threat that your muscle will decrease also. So increasing your protein intake can help preserve your lean mass during your weight loss.

Ed Delesky, MD (18:12)
And the only thing I would add there is that there's some suggestion. I've seen some studies out there and the obesity learning that I've been doing is that people on medications like GLP or GLP-GIP medications may think about doing a level of like 1.6 grams per kilogram of lean protein of what your body weight would be at a BMI of 26. That is increased from the like

very basic nutrition advice of 0.8 grams per kilogram to like sustain life. And of course that is very important to speak with your own doctor if you have any underlying conditions that would preclude you to do that. But I have been seeing some suggestion of doing that, but it's not medical advice by any means.

What can people do in terms of like outside of what they're doing in the kitchen? Is there something specific they can be doing in other parts of their life to help maintain their muscle mass?

Nicole Aruffo, RN (19:14)
Yes.

Ed Delesky, MD (19:16)
And what would that be?

Nicole Aruffo, RN (19:18)
Yes, exercise is another big one along with your diet, which again, diet and exercise with any sort of weight loss is not groundbreaking information. Sure. But resistance training and weight training is crucial for maintaining and improving our muscle strength and can help preserve muscle mass during weight loss.

So combining, increasing your protein or, you know, protein supplementation with resistance training can be particularly beneficial, especially in older adults. And then there is a potential challenge with exercise. Fatigue is sometimes reported as a side effect of being on a GLP one. So that could impact your ability to exercise or maybe exercise for like...

as intensely or as long as you would like to. anything's better than nothing.

Ed Delesky, MD (20:08)
Totally. And I think the standard recommendation that we've talked about in our exercise episodes and that I talk about every single day is two days of resistance training or strength training for the average individual. But if someone's on a GLP medication, you might even consider bringing that minimum or that floor to three days of resistance training to preserve muscle. Because there is suggestion that if you do these things, if you increase your protein intake like we've suggested,

or you increase the lean muscle mass or the resistance training that you are doing that you will preserve your skeletal muscle mass

And so as we're wrapping up the episode here, we want to acknowledge a couple of things. There are a lot of limitations in current data. Many weight loss trials don't prioritize accurate muscle mass measurements. And so we use this proxy measurement of lean body mass, which may not tell the whole story. There is a shifting idea to move towards functional outcomes. And so the definition of sarcopenia is moving towards muscle strength and function, not just lean mass. So

that is something that is evolving and how do we measure that will come. mean, there's a lot of different measurement tools that are beyond what we'll talk about today. And of course we need better assessment tools like using MRI for everyone is not going to be the answer at this point. It's too expensive and time intensive and other forms of like muscle mass measurement or body composition need to be made more reliable. And of course there needs to be a whole holistic approach.

when managing obesity with someone who's using a GLP, including incorporating some really important diet changes and some important exercise considerations to make this a whole treatment of a chronic disease. And so while we understand that GLP medications are effective for the treatment of obesity, we should understand their potential impact on muscle loss or change and take proactive steps to support muscle health.

because it's essential for positive outcomes and a sustainable outcome. And so talk to your own doctor or whoever's taking care of you to be able to get some more advice, more personal to you. But thank you for coming back to another week of your checkup. Hopefully you were able to learn something for yourself, a loved one or please find us on our website, find us on Instagram, send us an email, yourcheckuppod at gmail.com and most importantly, stay healthy, my friends.

Nicole Aruffo, RN (22:28)
a neighbor.

Ed Delesky, MD (22:40)
Until next time, I'm Ed Delesky I'm Nicole Arrufo Thank you and goodbye.

Nicole Aruffo, RN (22:44)
Bye.

Ed Delesky, MD (22:45)
This information may provide a brief overview of diagnosis, treatment, and medications. It's not exhaustive and is a tool to help you understand potential options about your health. It doesn't cover all details about conditions, treatments, or medications for a specific person. This is not medical advice or an attempt to substitute medical advice. You should contact a healthcare provider for personalized guidance based on your unique circumstances. We explicitly disclaim any liability relating to the information given or its use.

This content doesn't endorse any treatments or medications for a specific patient. Always talk to your healthcare provider for a complete information tailored to you. In short, I'm not your doctor. And make sure you go get your own checkup with your own personal doctor.

Nicole Aruffo, RN (23:22)
I am not your nurse.