Ozempic vs Wegovy vs Mounjaro

You are choosing between Ozempic, Wegovy and Mounjaro, or your doctor has offered a choice, and you want the real difference in plain words. Here it is. But there is a bigger question the usual comparison skips, which is what each one does to your muscle. That is the part that decides how you look and feel at the end, so do not stop at the weight loss numbers.

The quick answer

All three are weekly injections from the same family of drugs. Ozempic and Wegovy are the same active ingredient, semaglutide. Mounjaro is a different one, tirzepatide, and it works on two hunger hormones instead of one, which tends to produce more weight loss on average. Ozempic is registered here for diabetes and used off label for weight loss. Wegovy is the semaglutide version registered specifically for weight loss. Mounjaro is registered for diabetes and now cleared for weight management too.

That is the whole thing in a paragraph. Now the detail.

Ozempic

Ozempic is semaglutide. In South Africa it is approved for type 2 diabetes and to lower heart risk, and doctors prescribe it off label for weight loss, which is common. In trials people lost around 15 percent of their body weight over a year or more. It comes as a weekly pen.

Wegovy

Wegovy is also semaglutide, so it is the same drug as Ozempic. The difference is that Wegovy is registered for weight loss and comes in higher doses aimed at that goal. Weight loss lands in a similar range to Ozempic, around 15 percent in trials. It launched in South Africa in 2025.

Mounjaro

Mounjaro is tirzepatide, a different drug that hits two receptors rather than one. That dual action tends to produce more weight loss. In trials people lost around 20 to 22 percent of their body weight, higher than semaglutide on average. It comes as vials in South Africa.

The head to head on weight loss

On average, Mounjaro produces the most weight loss, with Ozempic and Wegovy close to each other a step behind. That is the trial picture. Your own result depends on your body, your dose and what you do alongside the drug. Plenty of people do very well on semaglutide. The averages are a guide, not a promise.

The part nobody compares, your muscle

Here is what the weight loss tables leave out. All three drugs cause muscle loss, because all three cause fast weight loss, and fast weight loss takes muscle along with fat. Trial data shows roughly a quarter of the weight lost on these drugs is lean tissue rather than fat, and semaglutide and tirzepatide look broadly similar on that front.

Now follow the logic. The drug that takes off the most total weight can also take off the most muscle in absolute terms, if you do nothing about it. So the strongest drug for weight loss is not automatically the best outcome for your body. What protects your muscle is not the brand you inject. It is the protein you eat and the training you do.

So which one is best?

The honest answer is the one your doctor recommends for your health and your budget. That is a medical decision, not something to pick off a blog. What matters far more for how you end up is what you do on top of the drug. On any of the three, if you eat enough protein and train against resistance, you keep your muscle and lose fat. If you do neither, you lose muscle on all three.

Read the main guide to keeping muscle on a GLP-1, the protein guide and the home training plan. Those decide your result more than the choice between these three names.

Cost and availability in South Africa

Ozempic runs about R2,700 to R3,200 a month at the common dose. Wegovy sits around R3,700 at its top dose with cheaper starting doses. Mounjaro runs around R3,400 to R4,000 a month. None are covered by medical aid for weight loss. The full breakdown is on the South Africa page.

Talk to your doctor

Which drug suits you depends on your health, your history and your goals. Your doctor makes that call with you. Bring one thing to the conversation. Tell them you want to protect muscle while you lose fat, and ask how your choice and dose fit that.

Common questions

Which GLP-1 is best for weight loss?

On average, Mounjaro produces the most weight loss in trials, with Ozempic and Wegovy close behind. Your result depends on your body and dose. The best choice for you is a medical decision for your doctor, based on your health and budget.

Which GLP-1 keeps the most muscle?

None protects muscle on its own. All three cause muscle loss through fast weight loss, and semaglutide and tirzepatide look similar on that. What keeps your muscle is eating enough protein and training against resistance, whichever drug you use.

Is Mounjaro better than Ozempic?

Mounjaro tends to produce more weight loss on average because it works on two hormones instead of one. Better depends on your situation, side effects and cost. Both work well, and your doctor helps you choose.

Is Wegovy the same as Ozempic?

Yes, they are the same active ingredient, semaglutide. Wegovy is the version registered for weight loss and comes in higher doses aimed at that. Ozempic is registered for diabetes and used off label for weight loss.

Can you switch between them?

People do switch, usually guided by side effects, results or cost, and always through their doctor. Never switch or change your dose on your own. Your prescriber manages any change safely.

Whichever you choose, the muscle side is up to you. Join the founding offer for the training plan, meal plan and tracking tools built for men over 45 on a GLP-1.

A quick note. This page compares these drugs for general information, not medical advice. Which one is right for you, and at what dose, is a decision for you and your doctor.