Strength Training on GLP-1s: How to Lose Fat Without Losing Muscle in Menopause
Why Muscle Matters on GLP-1s
Let me tell you about Sarah*, because her story is about to save you months of frustration.
She'd been on semaglutide for four months. Down 12.5Kg. Feeling fantastic. Then she sent me a photo of her arms with a single word: "Help."
They looked... smaller. Softer. Despite the weight loss, despite feeling better in her clothes, she could see she was losing something she didn't want to lose.
"I thought losing weight would make me look more toned," she told me. "Instead, I look... deflated."
Sarah had made the same mistake I see constantly with women on GLP-1 medications: she focused entirely on the number going down on the scale and forgot that how you lose weight matters just as much as how much you lose.
Here's the uncomfortable truth the prescribing doctors often don't mention: without the right type of exercise, you can lose almost as much muscle as fat on these medications.[1,2]
And muscle? Muscle is everything. It's your metabolism. Your strength. Your bone density. Your independence. This isn’t about aesthetics. It’s about being able to lift your suitcase, open jars, get up off the floor and stay fiercely independent at 70.
However - this is completely preventable. But it requires doing one thing that most women resist: lifting heavy things. Sarah started lifting three times a week with structured GLP-1 coaching support which helped her maintain results.
The Hidden Cost of GLP-1 Weight Loss
The clinical trials show impressive weight loss - 15-20% of body weight on average.[3,4] What they don't advertise is this: without resistance training, 25-40% of that weight loss comes from muscle, not just fat.[1,2]
If you lose 13kg, up to 5.5 of those kgs could be muscle.
Not fat. Muscle.
Learn more about how Mounjaro works in menopause and what to expect, so you understand the context behind your weight loss and how to protect your body
Why does this matter? Muscle is metabolically expensive tissue -it burns calories just existing.[5] When you lose muscle during weight loss, you're lowering the number of calories your body needs. This is why so many people regain weight after dieting.[6]
For women in perimenopause and menopause (when we're already losing muscle due to declining oestrogen), this becomes critical.[7] You're fighting a battle on two fronts.
And here's what really keeps me up at night: your bones respond to mechanical load. Muscle mass and bone density are connected -lose one, you typically lose the other.[8,9] Women already face higher osteoporosis risk after menopause. Losing muscle while on GLP-1s without resistance training? You're compounding that risk.
What Strength Training Actually Means
Let's be clear. When I say strength training, I don't mean:
45 minutes on the treadmill
Gentle yoga (though it has other benefits)
Light hand weights while watching TV
"Toning" workouts with 2kg dumbbells
Strength training means progressively challenging your muscles with resistance heavy enough that 8-12 repetitions feels genuinely difficult.[10]
This is where most women get it wrong. They're afraid of "bulking up" (you won't - women don't have the testosterone for that without serious effort).[11] So they stick with weights that feel comfortable.
And they wonder why nothing changes.
The research is clear: to maintain or build muscle during weight loss, you need weights challenging enough to trigger a muscle-building response.[12,13] We're talking about a weight where the last few reps are genuinely hard.
Your Action Plan: Four Non-Negotiables
1. Start Now, Not When You Hit Your Goal Weight
The biggest mistake? Waiting until you've lost all the weight to start lifting.
By then, you've already lost muscle. Research shows that resistance training during weight loss is far more effective at preserving lean mass than trying to rebuild afterward.[14]
If you started GLP-1 medication three months ago and haven't touched a weight? Start this week.
2. Train 2-3 Times Per Week (Minimum)
Studies consistently show that resistance training 2-3 times per week is the minimum effective dose for maintaining and building muscle.[15,16] Less than that? You're leaving results on the table.
This doesn't mean hours in the gym. A well-structured 30-45 minute session focusing on major muscle groups (legs, back, chest, shoulders) is enough.
3. Progressive Overload Is Everything
Here's the key: your muscles adapt.
If you lift the same 5kg dumbbells week after week, your body has zero reason to maintain muscle. You've adapted.
Progressive overload means gradually increasing the demand over time - adding weight, adding reps, or slowing down the movement.[17,18] Without progression, you're just going through the motions.
4. Eat Enough Protein (This Is Where Most Women Fail)
Resistance training alone isn't enough. Your muscles need amino acids to repair and rebuild.[19]
The research is unambiguous: combining resistance training with adequate protein during weight loss maintains significantly more muscle than either alone.[12,20]
You need roughly 1.6-2.2 grams of protein per kilogram of body weight daily when training during weight loss.[21] For a 70kg woman, that's 112-154 grams daily.
Yes, that's more than the standard recommendation. The standard was designed to prevent deficiency - not optimise muscle during weight loss.[22]
Distribute this across 3-4 meals with at least 25-30 grams per meal.[23] On GLP-1s, when you're genuinely not hungry, this requires strategy:
Prioritise protein first at every meal
Consider protein shakes if solid food feels overwhelming
Choose protein-dense foods (Greek yogurt, cottage cheese, lean meats, fish, eggs)
What to Expect: Muscle vs. Fat Loss
Let me set realistic expectations.
You probably won't build significant muscle while on GLP-1 medications. Building muscle requires adequate calories and these medications create a deficit.[24]
What you can do - and this is powerful - is maintain most of your muscle while losing fat. This is body recomposition.[25]
Your weight loss might slow down. Not because you're failing - because you're succeeding.
Muscle is denser than fat. If you're losing fat but maintaining muscle, the scale won't move as dramatically.[26] But your body composition will be dramatically better.
Don't let the scale discourage you. Take progress photos. Measure your waist. Track your strength gains. These matter more than weight alone.
The Bottom Line: How to Protect Your Muscle
You have a choice right now.
You can focus solely on the number on the scale and watch it drop - along with your muscle, your metabolism and your bone density.
If you’re approaching the end of your GLP-1 journey or noticing appetite changes, explore how to keep weight off after stopping Mounjaro for strategies that maintain results without losing hard-earned muscle.”
Or you can do this strategically. Lift wights that challenge you. Eat enough protein. And lose weight the way that serves your body for decades to come.
Sarah? She started lifting three times a week, upped her protein, and stopped obsessing over the scale. Six months later, she's down another 6kg but more importantly, she's stronger than she's been in 20 years.
Her arms? They look incredible.
Ready to protect your muscle while losing weight? Explore my Fuel and Move Well program.
Want personalised support? If you're on GLP-1s and want expert guidance to maximise fat loss while preserving muscle, book a Free 30-minute Menopause Clarity Call.
How you lose weight matters more than how much you lose. Learn how to keep weight off after stopping Mounjaro.
*Sarah is not her real name.
References
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