4th September 2026

GLP-1 Medications and Muscle Loss: Why Resistance Training Matters

GLP-1 medications such as semaglutide and tirzepatide have become an increasingly common part of weight management. For the right person, they can be incredibly effective. By reducing appetite and helping people feel fuller for longer, they can make achieving a calorie deficit significantly easier.
But there is one part of the conversation that I think deserves more attention: what type of weight are you actually losing?

When someone loses a significant amount of weight, we obviously want most of that weight to come from body fat. Unfortunately, that isn't always the case. Some loss of lean body mass can occur as well.

This isn't necessarily a problem unique to GLP-1 medications. It can happen with almost any substantial weight loss, particularly when someone is eating considerably less than they were before. However, because GLP-1 medications can have such a strong effect on appetite, maintaining muscle becomes something worth actively thinking about.

And that's where resistance training comes in.
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Weight loss isn't just about the number on the scalesIf someone tells me they've lost 15 kg, that's obviously useful information. But it doesn't tell me the whole story.

How much was fat?
How much was lean tissue?
Have they maintained their strength?
Are they moving better?
Has their fitness improved?
Can they do more than they could six months ago?
These things matter.

Two people could both lose exactly 15 kg and have very different outcomes. One could lose predominantly body fat while maintaining most of their muscle and strength. The other could lose a larger amount of lean tissue and end up noticeably weaker.

The scales would tell us they achieved the same thing. From a health and physical function perspective, they haven't.

Why are we worried about losing muscle?

Muscle isn't just something that's important for athletes or people who want to look muscular.

We need it to get out of a chair, climb stairs, carry groceries, work, exercise and remain physically independent as we get older. Skeletal muscle also plays an important role in metabolic health and glucose regulation.

So, while losing excess body fat may have significant health benefits, we don't necessarily want muscle disappearing with it.

This becomes even more important as we age. We naturally tend to lose muscle and strength over time, so losing additional muscle during a period of rapid weight loss may be particularly undesirable for an older adult.

Ideally, we want to come out the other side of weight loss lighter, but also strong, fit and physically capable.

This is where resistance training becomes importantWhen you're eating fewer calories and losing weight, resistance training essentially gives your body a reason to keep muscle.

It places demand on the muscles and tells the body, we still need this tissue.
You don't need to train like a bodybuilder either.

For many people, two or three resistance training sessions per week is a very good starting point. Those sessions might include exercises such as a leg press or squat, rowing movement, chest press, pulldown, hip hinge, step-up and a few additional exercises depending on the person's needs.

The important part isn't using a particular machine or following the perfect program.

The muscles need to be challenged appropriately, and the program needs to progress over time.

If you perform exactly the same easy exercises with exactly the same resistance indefinitely, there isn't much reason for the body to adapt. As you become stronger, the training stimulus generally needs to increase with you.

That might mean gradually increasing the resistance, repetitions, sets or difficulty of an exercise.

Protein matters too.

Resistance training is only part of the picture.

Your body also needs the building blocks required to maintain and repair muscle, and protein plays an important role here.

This can become a practical issue for some people taking GLP-1 medications. If your appetite has dropped considerably and you're eating much smaller portions, your overall protein intake may have dropped as well.

So the goal shouldn't necessarily be to just eat as little as possible because you're no longer hungry.

Food quality still matters.

A useful way to think about it is that resistance training provides the reason to keep muscle, while nutrition provides the resources to maintain it.

Individual protein requirements vary, and people with certain medical conditions may need specific advice. An Accredited Practising Dietitian can be particularly helpful here.

What about walking and cardio?

Keep doing it.

Resistance training isn't a replacement for cardiovascular exercise.

Walking, cycling, swimming and other aerobic activities are excellent for cardiovascular health, fitness and general wellbeing. Increasing everyday movement is also valuable, particularly for someone who was previously quite sedentary.

But walking alone doesn't provide the same stimulus for maintaining muscle and strength as appropriately prescribed resistance exercise.
Ideally, the two are used together.

For someone taking a GLP-1 medication, a good exercise program will often include resistance training, cardiovascular exercise and simply finding ways to move more throughout the week.

What should you actually monitor?Body weight is useful, but I wouldn't make it the only measure of success.

Depending on the person, I might also look at things like waist circumference, strength, walking capacity, cardiovascular fitness, exercise performance and general physical function.

If your waist circumference and body weight are coming down while you're maintaining or even improving your strength and fitness, that's a pretty good outcome.

You're not just becoming lighter. You're improving what your body can actually do.

Starting resistance training while taking a GLP-1 medication

There isn't a special "GLP-1 workout" that everyone needs to follow.

The fundamentals of good exercise programming still apply.

For many people, resistance training two to three times per week and exercising the major muscle groups is a sensible starting point. From there, the program can be progressed based on how the person responds.

The bigger consideration is the individual.

Someone who is 35, has trained for years and has no injuries requires a very different program from a 70-year-old who has knee osteoarthritis, lower back pain and hasn't exercised regularly for a decade.

That's why simply handing everyone the same list of exercises isn't particularly useful.

Where an Exercise Physiologist can helpFor people who are otherwise healthy and experienced in the gym, managing their own resistance training may be completely appropriate.

For others, particularly those with injuries, chronic health conditions or very little exercise experience, some professional guidance can make the process much easier.

An Accredited Exercise Physiologist can assess your current strength, fitness, mobility and physical function before developing an exercise program around your individual health and goals.

We can also monitor whether you're actually getting stronger as your weight decreases and adjust the program accordingly.

For someone losing a significant amount of weight with the assistance of a GLP-1 medication, I think that's an important distinction.

The goal isn't simply to weigh less.

It's to lose the weight you want to lose while keeping as much of the strength and physical capacity you want to keep.

GLP-1 medications can be a very effective tool for weight management. Combining them with appropriate resistance training, cardiovascular exercise and good nutrition gives you an opportunity to improve much more than the number you see on the scales.