How Does Mounjaro Work?

Mounjaro is a weight loss injection taken once weekly following a dosing schedule. It helps you lose weight by reducing your appetite and making you feel fuller, so it’s easier than before to follow a low-calorie diet.

Here at ZAVA, we can answer all your questions from how it works and how long it takes to work, to what to eat and how to get the best results during your treatment.

Brenda Ikeji

Medically reviewed by

Dr Brenda Ikeji

Last reviewed: 23 Oct 2024

What is Mounjaro?

Mounjaro is a prescription-only injection used to treat weight loss and type 2 diabetes. It was approved by The Medicines and Healthcare Products Regulatory Agency (MHRA) for weight management in the UK in January 2024.

The active ingredient in Mounjaro is tirzepatide. Tirzepatide contains GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) agonists. Together, these hormones work to reduce your appetite and make you feel fuller for longer. Mounjaro is the first of its kind dual GIP/GLP-1 receptor co-agonist for the treatment of both weight loss and type 2 diabetes.

How does Mounjaro work?

The active ingredient in Mounjaro, which is called tirzepatide, works by mimicking natural hormones in the body that control your appetite.

Tirzepatide is a GIP and GLP-1 agonist. It binds to the same receptors as these hormones and works by slowing down how fast your stomach empties, making you feel fuller for longer. It also decreases your appetite and cravings. Together, these effects can help you with your weight loss journey.

These same ingredients can help if you have type 2 diabetes by improving insulin production, and reducing glucose levels. These effects together can bring down blood sugar levels and keep them within the normal range.

However, tirzepatide is not an insulin – it works by helping your body produce more of it. Your doctor should advise the right treatment plan for you and your diabetes depending on your personal requirements and needs.

How long does Mounjaro take to work?

You may feel your appetite start to lessen shortly after you begin taking Mounjaro, however, it may take a few weeks to feel the full effect. Clinical trials show that most people can expect to lose at least 5% of their weight after taking it for 8 weeks.

The same study reported that weight loss whilst taking Mounjaro is most noticeable after 72 weeks of taking the medication.

Once your dosage is gradually increased, your results should be more noticeable. Following the instructions of your doctor and their personalised advice will enable you to achieve the desired results you need from your weight loss journey. For example, Mounjaro works best when following a healthy diet and exercise routine and this will be prescribed alongside your treatment.

How much weight can I lose on Mounjaro?

A clinical study has reported that you can lose up to 22.5% of your starting weight while taking the highest maintenance dose of 15 mg after just 72 weeks.

In the same 72-week study, the percentage of participants who had a weight reduction of 5% or more was:

  • 89.4% (on the 5mg dose)
  • 96.2% (on the 10mg dose)
  • 96.3% (on the 15 mg dose)
  • 27.9% (on a placebo)

Mounjaro weight loss week-by-week graph

The monthly results with Mounjaro on different dosages

How to get the best results from Mounjaro

To ensure that you stay on target with your weight loss goals and achieve the best results from Mounjaro, you must follow your doctor’s personalised instructions and the dosage schedule.

We also recommend that whilst taking Mounjaro you should stick to a regular balanced diet and exercise plan. This is because Mounjaro works with your digestive system, appetite control centres, and blood sugars to help you achieve your weight loss goals. It doesn’t cause weight loss on its own, but it minimises hunger levels and keeps you feeling fuller for longer so you can eat less and lose more weight. Following a nutritional plan will not only help your progress, it will minimise the potential side effects of Mounjaro too.

Your doctor can advise the steps to take with your nutrition in order to help you succeed and meet your weight loss targets in a way that is suitable for you and your body.

At ZAVA, our doctors are here to help and can be contacted via message through your online account to ask questions. We also provide a free weight loss guide to aid you in your weight loss journey when you order your treatment with us.

Start Your Journey With Mounjaro

Remember, it is also important that you set realistic weight loss goals, and track your progress to stay motivated during your treatment, some people do this through:

  • diaries or journals
  • log books
  • meal planners
  • weight trackers

Planning, journaling and tracking your weight loss will enable you to monitor any symptoms, your dosages, measurements, and even nutritional notes. It can be a space for you to manage your journey.

We have free trackers included in our weight loss support pack that you can print out and stick on your fridge or cupboard door to keep you motivated during your treatment with Mounjaro.

What to eat when taking Mounjaro

Mounjaro works with your digestive system, so it is important that you make the right nutritional and lifestyle changes while taking it.

This means making sure to eat a balanced diet that is low in fat. By eating a balanced, nutritious diet and focusing on reducing your daily calories by 600 a day, you can provide your body with what it needs while reaching a calorie deficit and allowing your weight loss journey to flourish throughout your treatment steadily and healthily.

Recommended foods for a balanced diet:

  • non starchy vegetables – lettuce, cucumber, tomatoes, courgette, aubergine, cabbage, mushrooms, etc
  • low-fat protein – chicken, tofu, fish, chickpeas, beans, eggs
  • carbohydrates – rice, potatoes, whole wheat pasta, couscous, sweet potatoes
  • healthy fats – olive oil, walnuts, pumpkin seeds, houmous
  • dairy protein – yoghurt, cheese, milk, eggs
  • fruit – bananas, orange, strawberries, grapes, etc

There is more detailed information on what a Mounjaro diet plan should look like in our guide, including recipe ideas and information on nutrition while taking it. There is also a Food Scanner app for when you’re on the go in the supermarket, so you can check if products fit the requirements of what you need in your diet. When shopping, it’s best to avoid highly-processed foods and stick to whole foods and ingredients that you can make into meals yourself.

We suggest avoiding high-fat and high-sugar foods and drinks too. Some examples of these are (but not limited to):

  • fried foods
  • crisps
  • chocolate, cakes, and biscuits
  • sugary drinks
  • alcohol
  • pizza
  • fatty cuts of meat
  • coconut oil and coconut cream
  • meat products – like sausages and pies
  • cream and ice cream

Eating foods that are higher in fat and sugar can counteract Mounjaro’s appetite-suppressing effects and in turn increase side effects. Eating too much fat will also prevent weight gain and can even cause weight gain on Mounjaro.

At ZAVA we provide a nutritional guide with your weight loss medication, completely curated by our in-house doctors and nutritionist. This includes trackers, planners, meal swap suggestions, and more.

Medically reviewed by

brenda-ikeji.png Dr Brenda Ikeji

Brenda studied medicine at St Georges University of London and has most recently worked in John Radcliffe Oxford University Hospitals, covering acute and general medicine.

Last reviewed: 23 Oct 2024

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