The number on the scale is finally going down. Twenty pounds in four months, maybe more. For the first time in years, it feels honest.

Then one morning you catch your arm in the mirror. Or the back of your thigh. And something looks different. It’s softer. Smaller. And it isn’t fat.

If you’ve started a GLP-1 medication like Ozempic, Wegovy, Mounjaro, or Zepbound, there’s a side effect the bottle doesn’t warn you about. Some of the weight you’re losing isn’t fat at all. It’s muscle — the tissue that keeps you strong, steady, and able to do the things you love.

This isn’t a reason to stop your medication. These medications have changed millions of lives, and yours may be one of them. But there’s a part of this story your prescriber may never bring up. And it’s the part that decides how you’ll feel not just at your goal weight, but for years after.

Let’s walk through what’s really happening — and the simple plan that helps you protect your strength while the weight comes off.

The part most people never hear about

When you lose weight, you picture losing fat. That’s the goal. But your body doesn’t only let go of fat.

The two largest studies of these medications used DEXA scans to measure exactly what people lost. DEXA is the same gold-standard body scan used in muscle and bone research. The results were clear.

In the big semaglutide study known as STEP-1, people lost about 15% of their body weight — and almost 10% of their lean mass went with it. That’s more than 1 in 3 pounds lost coming from muscle, not fat.¹

In the tirzepatide study known as SURMOUNT-1, people lost even more total weight. Their muscle loss came to about a quarter of the total.² And because the total was bigger, the actual pounds of muscle lost could be just as high, or higher.

A 2024 review of the semaglutide research found the number can run even higher — up to 40% of the weight lost coming from muscle when people do nothing to protect it.³ So here’s the number worth remembering: up to 40% of the weight you lose on a GLP-1 can be muscle, not fat.

Here’s what that means in real life. If you lose 40 pounds and do nothing to protect your muscle, somewhere between 10 and 16 of those pounds could come from lean tissue. That’s the muscle that powers your hike, your tennis serve, and your easy first step out of bed in the morning.

Why it happens — three things stacking up

This isn’t a flaw in your medication. It’s three normal forces landing at the same time.

You’re in a calorie deficit. Any time you lose weight, some muscle comes with it. That’s true of every diet ever tried. What’s different here is the size of the loss. These medications can drive far more weight loss than diet alone — so the muscle that comes with it can add up fast.

Your protein quietly drops. This is the big one. These medications work by turning down your appetite. That’s why they work. But when you’re barely hungry, protein is usually the first thing to fall. And protein is the raw material your body needs to hold onto muscle. Many people drift down to half the protein they need without ever noticing.

Your body is past 40. After about 40, your muscles get a little “hard of hearing.” They stop responding to protein and exercise the way they did in your 20s. Scientists call this anabolic resistance. It means you need a stronger signal — more of the right amino acids and a real reason to keep the muscle — just to hold steady.⁴ ⁵

Put those three together and the math is tough. A big calorie deficit. Less protein coming in. And a body that needs more of the right signal, not less. Without a plan, the muscle keeps slipping.

The clock is the part most people miss

Here’s what makes this urgent, and it’s the fact almost nobody talks about.

Muscle is easy to lose and slow to rebuild. That’s true for everyone. After 40, the gap gets wider — and not in your favor.

Researchers have shown this directly. When older adults stopped using one leg for just two weeks, they lost real muscle and strength fast. Then came the telling part. After weeks of training to build it back, the younger adults fully recovered. The older adults did not. Their muscle size and strength only came back part of the way, even after putting in the work.⁶

And building new muscle is slow going. After 50, the same workout builds about half the muscle it would have at 25. In one study, older adults who strength-trained for three months gained only about half the muscle that younger adults gained from the very same program.⁷ A larger review of dozens of studies found the same thing — the muscle-building response to a workout is less than half as strong in older adults.⁸

Now put those facts side by side. The muscle you have right now is the easiest muscle you will ever have. Keeping it is far less work than winning it back later. And some of what you lose during fast weight loss, you may never fully get back.

So this isn’t a “deal with it someday” problem. Every week on a GLP-1 medication without a plan is muscle quietly leaving — muscle that gets harder to rebuild with each year that passes. The best time to protect it is while you still have it.

The muscle you have right now is the easiest muscle you’ll ever have.

Picture what you’d be giving up

The number on the scale today isn’t the real story. The real story is what your body can still do — this year, next year, and the ones after that.

So picture it.

Your family plans a trip to the mountains. There’s a trail everyone wants to hike, the one that climbs to the lookout your grandkids won’t stop talking about. And you find yourself quietly doing the math on whether your legs can make it. Then you wave everyone on ahead and wait at the bottom. Not because you didn’t want to go. Because the strength you used to count on just isn’t there anymore.

Picture the ski trip where you stay back at the lodge. The bike ride you cut short. The kayak you wave off. The moment someone you love reaches out for a hand up, and you’re not sure you’re the one who can give it.

None of that feels close right now. But it’s being decided right now, one lost pound of muscle at a time. The strength you give away while the weight comes off is the strength you’ll be reaching for the next time something fun and a little hard comes your way.

And there’s a nearer risk too. Most people who stop these medications regain about two-thirds of the weight within a year.⁹ Here’s the part that stings. The weight comes back as fat faster than it comes back as muscle.¹⁰ So you can land right back at your old weight, only now with less muscle and more fat than when you started. A smaller win on the scale. Softer in the mirror. Weaker than the day you began.

Here’s how that can play out. Picture a 48-year-old woman who starts at 215 pounds. A year on the medication, she’s down to 183 and thrilled — 32 pounds gone. But about 11 of those pounds were muscle. A year after she stops, she’s back up to around 205. The catch is what came back. Almost all of the regain was fat. So she ends up about 10 pounds lighter than the day she started — but her fat is nearly back to where it began, while her muscle is down about 8%. She didn’t just lose her progress. She traded muscle for fat. Everyone is different, but that pattern is common.

That’s the path on autopilot. Now picture the other one.

Picture being the one who leads the group up the trail. The one who says yes to the trip, the bike ride, the long day on your feet, the early start. Picture reaching your goal weight and feeling strong in your own body — lean, capable, ready for the next thing — instead of fragile.

That version of you isn’t luck or good genes. It’s muscle you chose to protect, starting now, while you still have it.

The good news — this is fixable

A woman riding a bicycle on a tree-lined road at sunset, smiling and relaxed.

When people lose weight on a clear plan — enough protein, plus a little strength training — they hold onto far more of their muscle. In older adults, adding strength training saved almost all of the muscle that dieting alone would have cost them — about 90% of it, in one review.¹¹ So here’s the hopeful number: with simple strength training, you can keep up to 90% of the muscle you’d otherwise lose. There’s even research in people on a GLP-1 medication — those who added exercise held onto their muscle and finished leaner than those on the medication alone.¹² The plan works. It just has to actually get done.

It comes down to four simple levers, each backed by research.

Lever 1: Protein, every day, at the right amount

This is the foundation. Adults losing weight need quite a bit more protein than the old standard advice — and more than younger adults need, because of that “hard of hearing” effect after 40.⁵ ¹³ A good target for many people is around 30 grams of protein at each meal.

When your appetite is low, hitting that with food alone is hard. A clean protein or essential-amino-acid drink helps you close the gap without filling up a stomach that’s already had enough.

Lever 2: Strength training, two or three times a week

You don’t need to live in the gym. Two or three short sessions a week is enough to send the signal. Bodyweight squats, a few pushups, some dumbbells or bands — that’s it.

The rule is simple. Muscle that gets used gets kept. Muscle that sits idle is the first thing your body lets go of when calories are low. For adults past 40, strength training is one of the most powerful things you can do to protect your muscle and your bones for the long run.

Lever 3: Four specific nutrients, at researched doses

Decades of research point to four nutrients with the strongest evidence for protecting muscle, especially when you’re eating less or past 40. Each works in a different way.

Essential amino acids, or EAAs, are the building blocks that tell your muscles to repair and rebuild. In studies of older adults, EAAs raised muscle-building activity within hours.⁴ When you’re eating less, these become extra valuable — they send the “build” signal without needing a big meal.

Creatine monohydrate is one of the most-studied nutrients in all of sports science. Paired with strength training in older adults, it helped people add more lean muscle than training alone.¹⁴ It also helps your muscles keep their energy and strength while you’re in a calorie deficit.

Calcium HMB is made from the amino acid leucine. While EAAs say “build,” HMB acts more like a guard that helps slow muscle breakdown. In a year-long study of older adults, calcium HMB paired with vitamin D3 supported better muscle strength and function.¹⁵

Vitamin D3 keeps the line of communication open between your brain and your muscles. It also supports your bones. Studies show vitamin D works best alongside the other three — it helps the whole signal come through loud and clear.¹⁶

These four are the nutrients most of the research lands on for protecting muscle after 40. They’re also the exact four in Balaena Muscle Essentials — one daily scoop, each nutrient at the researched dose. One drink, mixed in water, made to be easy on the days when your appetite and energy are low.

Lever 4: Water, electrolytes, and a daily rhythm

This one is the simplest and the most ignored. When your appetite drops, so does your water and electrolyte intake. And being low on fluids makes everything worse — more tired, weaker workouts, more queasy. Aim for plenty of water through the day, add a pinch of electrolytes when you’re sweating or dragging, and give your daily routine the respect it deserves. Because it matters.

A simple way to remember it: the Balaena Blueprint

We built the Balaena Blueprint for adults over 40, and it fits anyone on a GLP-1 medication just as well. It’s three steps.

Fuel. Take one daily scoop of Balaena Muscle Essentials. Four research-backed nutrients — EAAs, creatine, calcium HMB, and vitamin D3 — in one drink.

Stimulate. Strength train two or three times a week. Twenty-five minutes counts. Showing up matters more than going hard.

Nourish. Aim for about 30 grams of protein per meal, drink your water, and make your bites count — because every bite counts more when you’re eating less.

That’s the whole plan. It’s not fancy, and it’s not a guess. It’s built on years of research behind those four nutrients.

What to do this week

If you’re on a GLP-1 medication, here are five things worth doing before the week is out:

  1. Add up your protein for three days. Just write down what you eat that has protein. If you’re coming up short, you’ve found an easy, high-value fix.
  2. Put two 25-minute strength sessions on your calendar. Bodyweight or dumbbells. Block them off like real appointments.
  3. Start a simple daily muscle-defense scoop. Balaena Muscle Essentials is built for exactly this moment — one scoop, water, four researched nutrients.
  4. Talk to your prescriber about protein and strength. Most providers are glad you asked. Few will bring it up first.
  5. Change the goal in your head. The scale is one number. The strength and energy you keep when the scale stops moving — that’s the real win.

Aging is something we all do. Decline is not. And with a simple plan, neither is losing the muscle you’ll want for the rest of your life.

Ready to protect your muscle while you lose the weight? Explore Balaena Muscle Essentials

Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary. The information provided is not intended as medical advice and should not replace consultation with a qualified healthcare professional. If you are taking a prescription medication, including a GLP-1 medication, talk to your prescriber before adding a dietary supplement to your routine.

Research Citations

  1. Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine. 2021;384(11):989–1002. PMID: 33567185.
  2. Look M, Dunn JP, Kushner RF, et al. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study. Diabetes, Obesity and Metabolism. 2025. PMID: 39996356.
  3. Conte C, Hall KD, Klein S. A systematic review of the effect of semaglutide on lean mass: insights from clinical trials. 2024. PMID: 38629387.
  4. Volpi E, Kobayashi H, Sheffield-Moore M, Mittendorfer B, Wolfe RR. Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults. American Journal of Clinical Nutrition. 2003;78(2):250–258. PMID: 12679447.
  5. Churchward-Venne TA, Holwerda AM, Phillips SM, van Loon LJC. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. Journals of Gerontology Series A. 2016;71(6):828–832. PMID: 24787742.
  6. Suetta C, Hvid LG, Justesen L, et al. Effects of aging on human skeletal muscle after immobilization and retraining. Journal of Applied Physiology. 2009;107(4):1172–1180. PMID: 19661454.
  7. Welle S, Totterman S, Thornton C. Effect of age on muscle hypertrophy induced by resistance training. Journals of Gerontology Series A. 1996;51A(6):M270–M275. PMID: 8914498.
  8. Davies RW, Lynch AE, Kumar U, Jakeman PM. Characterisation of the muscle protein synthetic response to resistance exercise in healthy adults: a systematic review and exploratory meta-analysis. Translational Sports Medicine. 2024;2024:3184356. PMID: 38716482; PMCID: PMC11074832.
  9. Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism. 2022;24(8):1553–1564. PMID: 35441470.
  10. Beavers KM, Lyles MF, Davis CC, Wang X, Beavers DP, Nicklas BJ. Is lost lean mass from intentional weight loss recovered during weight regain in postmenopausal women? American Journal of Clinical Nutrition. 2011;94(3):767–774. PMID: 21795437.
  11. Sardeli AV, Komatsu TR, Mori MA, Gáspari AF, Chacon-Mikahil MPT. Resistance training prevents muscle loss induced by caloric restriction in obese elderly individuals: a systematic review and meta-analysis. Nutrients. 2018;10(4):423. PMID: 29596381.
  12. Lundgren JR, Janus C, Jensen SBK, et al. Healthy weight loss maintenance with exercise, liraglutide, or both combined. New England Journal of Medicine. 2021;384(18):1719–1730. PMID: 33951361.
  13. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association. 2013;14(8):542–559. PMID: 23867520.
  14. Chilibeck PD, Kaviani M, Candow DG, Zello GA. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access Journal of Sports Medicine. 2017;8:213–226. PMID: 29138605.
  15. Rathmacher JA, Pitchford LM, Khol P, et al. Long-term effects of calcium β-hydroxy-β-methylbutyrate and vitamin D3 supplementation on muscular function in older adults. Journals of Gerontology Series A. 2020;75(11):2089–2097. PMID: 32674138.
  16. Bauer JM, Verlaan S, Bautmans I, et al. Effects of a vitamin D and leucine-enriched whey protein nutritional supplement on measures of sarcopenia in older adults (PROVIDE study). Journal of the American Medical Directors Association. 2015;16(9):740–747. PMID: 26170041.