If you are on a GLP-1 medication and losing weight, that is not automatically good news. Not all weight loss is equal. Some of what leaves your body is fat. Some of it, if you are not eating the right way, is muscle. And losing muscle while on Ozempic, Wegovy or Mounjaro is one of the most common and least-discussed risks of these medications.

The good news is that it is largely preventable. What you eat, and specifically how much protein you eat, makes a significant difference to how much muscle you keep during your GLP-1 journey.

Does Ozempic cause muscle loss?

Yes, it can. And the numbers are worth knowing.

Research on GLP-1 medications consistently shows that somewhere between 20 and 40 percent of the weight lost can come from lean muscle mass rather than fat tissue. That is not a fringe finding. It shows up across multiple studies, including the large STEP trials that formed the clinical basis for semaglutide's approval.

Why does this happen? GLP-1 medications work by suppressing appetite significantly. Total food intake drops. When the body is in a sustained calorie deficit and not getting enough protein, it starts breaking down muscle tissue to meet its energy and amino acid needs. The medication does not discriminate between fat and lean mass. Without the right nutritional support, you lose both.

The risk is higher in certain groups. Older adults lose muscle more readily than younger people. Women going through perimenopause or menopause are also more vulnerable due to declining oestrogen levels, which play a role in muscle maintenance. People who were already low in protein before starting medication have less buffer to draw from.

This is not a reason to avoid GLP-1 medications. They are effective tools with meaningful health benefits. It is a reason to take nutrition seriously alongside them.

Why muscle matters beyond how you look

Muscle loss is often framed as an aesthetic concern. It is much more than that.

Muscle tissue is metabolically active. It burns energy at rest in a way that fat tissue does not. The more lean muscle mass you carry, the higher your resting metabolic rate and the more energy your body burns throughout the day just functioning. When you lose significant muscle during rapid weight loss, your metabolism slows. That slower metabolism makes it considerably harder to maintain your results once the medication stops, or even while you are still on it.

Muscle also supports physical strength and functional capacity. This matters especially as you age. Maintaining lean mass protects your joints, reduces injury risk, supports bone density and keeps you physically capable of the activities that matter to you. Muscle loss in the context of GLP-1 medication is not just a number on a DEXA scan. It has downstream effects on how you feel and function for years.

There is also the weight regain question. Studies following people after they stop GLP-1 medications show that appetite returns and weight regain is common. People who enter that transition with more muscle mass, and stronger nutrition habits, are considerably better positioned to maintain their results. Protecting your muscle during the medication phase is, in large part, protecting your results after it.

The most important lever: protein

If there is one nutritional change that makes the biggest difference to muscle preservation on GLP-1 medications, it is eating enough protein. This is not a trend or a social media talking point. It is basic physiology.

Protein provides the amino acids your body needs to maintain and repair muscle tissue. When total food intake drops significantly, as it does on GLP-1 medications, protein is often the first macro to fall short. People eat less across the board and do not compensate by making their smaller meals more protein-dense. The result is a protein deficit that accelerates muscle loss.

Current evidence supports a protein intake of around 1.2 to 1.6 grams per kilogram of body weight per day for people on GLP-1 medications. For a 70-kilogram person, that is roughly 84 to 112 grams of protein per day. For many people, that is more than they were eating before starting the medication, and more than they feel like eating once their appetite has reduced. Getting intentional about protein is not optional. It is the most important nutritional job you have on this medication.

High-protein foods to build your meals around:

1. Eggs and egg whites (6 to 7 grams per egg)
2. Greek yoghurt, plain (15 to 20 grams per 200g serve)
3. Cottage cheese (14 grams per 100g)
4. Chicken breast (30 grams per 100g cooked)
5. White fish and salmon (20 to 25 grams per 100g)
6. Tinned tuna or salmon (20 to 25 grams per 100g)
7. Lean beef and pork (25 to 30 grams per 100g)
8. Lentils and chickpeas (9 grams per 100g cooked)
9. Tofu and tempeh (10 to 20 grams per 100g depending on firmness)
10. Low-fat dairy including milk and cheese

The practical goal is to anchor every meal around at least one of these. A palm-sized serve of protein at breakfast, lunch and dinner gets most people close to their daily target. For a full breakdown of how to eat well on GLP-1 medications generally, read our guide to what to eat on Ozempic.

A note on protein timing: spreading your protein across meals works better than loading it all into one sitting. Your body can only use so much protein for muscle synthesis at once. Three meals with a solid protein source each is more effective than one large protein-heavy meal and two low-protein ones.

The second lever: resistance exercise

Nutrition is the primary tool for muscle preservation on GLP-1s. Exercise is the second.

Resistance training, which includes bodyweight exercise, weights, resistance bands and Pilates, sends a signal to your muscles to maintain and rebuild. That signal, combined with adequate protein intake, is a powerful combination for protecting lean mass during weight loss.

You do not need to be in the gym five days a week. Two to three sessions per week of moderate resistance exercise is enough to make a meaningful difference. The key is consistency over intensity. A simple routine you stick to beats an ambitious programme you abandon after two weeks.

If you are new to resistance training or managing other health conditions, speak with your GP or an exercise physiologist before starting. The goal is to support your GLP-1 journey, not to add another stressor.

What a muscle-protective eating day looks like

Abstract targets are one thing. Here is what getting enough protein actually looks like across a day, keeping in mind that portions on GLP-1 medications are often smaller than usual.

Breakfast Two scrambled eggs on wholegrain toast with a side of Greek yoghurt. Approximately 30 to 35 grams of protein. Small, balanced, takes ten minutes.

Lunch A bowl with tinned salmon or grilled chicken, a mix of salad vegetables, half a cup of cooked quinoa or brown rice, and a drizzle of olive oil dressing. Approximately 30 to 35 grams of protein. Does not require cooking from scratch if you batch-prep proteins at the start of the week.

Dinner A palm-sized portion of lean beef, fish or tofu with roasted vegetables and a small serve of sweet potato or wholegrains. Approximately 25 to 30 grams of protein. Keep it simple. The goal is balance, not complexity.

Snack (if needed) A small tub of Greek yoghurt, a boiled egg with crackers, or a handful of nuts with some cheese. Approximately 10 to 15 grams of protein.

Total across the day: roughly 95 to 115 grams. That puts most people within the evidence-based target range.

Signs you may not be eating enough protein

Reduced appetite on GLP-1 medications makes it easy to fall short without realising it. A few signs worth knowing:

You feel weak or tired more than usual, particularly during physical activity. You are losing weight faster than expected but also noticing changes in strength or muscle tone. You are eating very little at meals and not making protein the priority when you do eat. You are experiencing hair thinning or loss, which can be a sign of inadequate protein alongside other nutrients.

None of these are definitive on their own. But if several resonate, it is worth reviewing your protein intake before your next consultation or speaking to your dietitian sooner.

When dietitian support makes a difference

General targets like "eat 1.2 to 1.6 grams of protein per kilogram" are useful as a starting point. Working out exactly what that means for your body, your food preferences, your dose and your stage of the GLP-1 journey is a different task entirely.

Our team of Accredited Practising Dietitians works with GLP-1 patients across Brisbane and via telehealth anywhere in Australia. A first consultation gives us a full picture of where your nutrition is right now, where the gaps are, and what a realistic, personalised plan looks like for you.

Book a consultation to get your personalised protein targets.