Protecting Your Muscle on GLP-1 Medication: A Dietitian’s Guide

If you have been prescribed a GLP-1 medication, you may have heard that some of the weight you lose can be muscle rather than fat. It is a fair thing to ask about. Muscle keeps you strong, steady on your feet and able to do everyday things with ease, so looking after it matters as much as the number on the scales. This guide explains what the research shows, why protein tends to slip when your appetite is small, what strength activity can do, and where a dietitian helps. It is written for people already on treatment, alongside their prescriber.

Why muscle matters

Muscle is more than appearance. It is what lets you climb stairs, carry the shopping, get up from a chair and catch yourself when you trip. It also tends to shrink as we age, so losing extra muscle at the same time as losing weight is a particular concern for older adults.

Exercise & Sports Science Australia’s chief executive, Katie Lyndon, said in the September 2026 joint statement with Dietitians Australia: “Maintaining muscle mass plays a critical role in strength, mobility, and metabolic health.” The statement warns that substantial weight loss on these medicines can have unintended effects, including “nutrient deficiencies, lean tissue loss, function loss, and an increased risk of frailty and falls.” Those are the two professional bodies’ views as they argue for funded support (we explain the call in our post on the joint statement). They describe risks, not something that happens to everyone.

How much muscle can be lost?

There is no single answer, because studies measure it differently and people differ. A 2025 review of the evidence reported that participants in trials of these medicines lost 10% or more of their muscle mass over 68 to 72 weeks, which the authors compared with roughly 20 years of age-related muscle loss. Estimates vary between studies, so treat the figure as a guide to the size of the concern rather than a prediction for you.

Some loss of muscle can happen with any rapid weight reduction, so this is not unique to these medicines. What makes it worth planning for is how quickly appetite can drop, and how many people end up eating much less protein than before.

Muscle matters again if treatment stops. Australian Prescriber notes that weight that is regained may come back proportionally more as fat than as muscle, and recommends that people are supported to build and maintain muscle both while on treatment and after stopping. Our guide to stopping GLP-1 medication covers that stage.

Protein: the first thing to slip

When your appetite is small, protein foods are often the ones left behind. They are filling, and meat or eggs can be off-putting when you feel nauseated. A 2025 review of studies on these medicines reported that protein intake is frequently inadequate, and another review recommends that it is monitored. Dietitians Australia and ESSA make the same point in their joint statement: eating less makes it “harder to get enough protein, vitamins and minerals”.

A few habits help without turning every meal into a project:

• Start with the protein food on your plate, then add the rest if you still have room.
• Include a protein food each time you eat, snacks included, rather than saving it for one big meal.
• Choose softer, moister or cooler options when nausea or cooking smells put you off.
• Keep easy options on hand for low-appetite days, so you are not relying on the energy to cook.

How much protein is right for you depends on your age, health, kidney function, activity and what you are eating now, which is why general targets can mislead. If you have kidney disease, check with your doctor before changing how much protein you eat. Our guide to what to eat on GLP-1 medication has more on eating well when you are barely hungry.

Working out where your protein is slipping, and how to fit it in with the foods you will actually eat, is something we do in a consult. About the GLP-1 consult →

Strength activity: the other half

Reviews recommend resistance (strength) activity as a key way to limit muscle loss during weight reduction. A 2025 review states that it “has been shown to effectively minimize loss of muscle mass and function”. Another review notes that the evidence for it alongside these medicines specifically is mixed, so it is best seen as strongly recommended rather than a promise.

Strength activity does not need a gym. Options include:

• Bodyweight moves such as sit-to-stands from a chair, wall push-ups, step-ups and squats to a chair.
• Resistance bands, light weights or household items such as full water bottles.
• Daily-life strength: carrying the shopping, taking the stairs, gardening.

Build up gradually, and a few sessions a week is a reasonable place to start. If you have joint, heart or balance concerns, or have not exercised for a while, check with your GP first. An Accredited Exercise Physiologist can design a program around your health, and ESSA has a directory of accredited practitioners. If you feel dizzy or faint, stop, sit down and drink some water, and mention it to your doctor.

Keeping it balanced

For some people a focus on protein and exercise can tip into rigid rules or compulsive exercise. If food and movement start to feel like a source of anxiety, or you notice you are eating less to “earn” something or exercising to compensate, please talk to someone. Ausclin also offers eating disorder support, and we will talk it through gently and without judgement.

When to talk to your doctor