There are several reasons why you may not be losing weight on Mounjaro. For many people, it is because they are still in the early stages of treatment, their dose is still being increased, or their body is still adjusting.

For others, weight loss may be affected by eating habits, activity levels, side effects, missed doses, other medicines, or health conditions. The most common reasons include:

• You have only just started treatment
• You are still on a lower dose
• Your weight loss has slowed or plateaued
• You are eating more calories than you realise
• You are not moving as much as you should
• Side effects are affecting your routine
• You have missed doses
• Another medicine or health condition is affecting your weight

Weight loss is rarely a straight line. It is normal for your weight to move up and down from week to week, even when you are making progress.

If you have only recently started using Mounjaro, you may not notice weight loss straight away. Mounjaro supports gradual weight loss over time. You may feel your appetite reduce before you see a clear change on the scales. This can be frustrating, but it is common.

Your body also needs time to adjust to treatment. Some people lose weight in the first few weeks, while others may need longer, especially if they are still on the starting dose.

Try not to judge your progress too early. Instead, track your weight over several weeks and look for other signs that things are changing, such as feeling full sooner, snacking less, having fewer cravings, or noticing your clothes fit differently.

Mounjaro treatment usually starts on a low dose so your body can get used to the medicine.

The starting dose is usually 2.5mg once a week for 4 weeks. After this, your prescriber may increase your dose gradually if it’s suitable for you. This step-by-step approach can help reduce side effects such as nausea, diarrhoea, constipation, or stomach discomfort.

Because of this, you may not see your full weight loss response straight away. The lower starting dose is mainly used to help your body adjust. Some people notice more weight loss after their dose has increased, but this should only happen under your prescriber’s guidance.

Don’t increase your dose early or change your treatment plan without speaking to your prescriber.

A weight loss plateau is when your weight stays around the same for a while after a period of progress. This can happen with or without Mounjaro, and it doesn’t always mean the treatment has stopped working.

As you lose weight, your body may need fewer calories than before. Your routine may also change without you noticing. For example, you may move less because you are eating less, feel more tired, or become less active outside planned exercise.

The scales can also be affected by water retention, constipation, salt intake, menstrual cycle changes, stress, sleep, and changes in your activity levels. If your weight has not changed for a few weeks, try looking at your wider progress too. Waist measurements, how your clothes fit, appetite, cravings, energy, blood pressure, fitness and strength can all show progress that the scales may not capture.

Mounjaro can help reduce appetite, but it does not replace healthy eating habits.

To lose weight, you usually need to use more energy than you take in over time. This is called a calorie deficit. Mounjaro can make this easier by helping you feel fuller and reducing hunger, but the food and drinks you choose are just as important.

You may be eating more calories than you realise if you often have:

• Large portions
• High-calorie snacks
• Sugary drinks
• Alcohol
• Takeaways
• Sauces, oils, or dressings
• Sweet coffees
• Weekend treats that add up

You don’t need to follow an extreme diet. Small changes can make a big difference, especially if they are changes you can keep doing.

Try to choose meals that include protein, fibre, and plenty of vegetables or fruit. Protein-rich foods such as eggs, fish, chicken, tofu, beans, lentils, yoghurt, and cottage cheese can help you feel fuller for longer and support muscle maintenance while losing weight

Although eating too much can slow weight loss, eating too little can also cause problems.

Mounjaro can reduce your appetite, and some people find they skip meals or eat very small amounts. This may leave you tired, weak, constipated, or even more likely to snack later. It can also make it harder to get enough protein, fibre, vitamins, and minerals.

If your appetite is low, focus on smaller, balanced meals rather than skipping meals completely. Try to include protein with meals and drink enough fluids throughout the day. Speak to your pharmacist or prescriber if side effects are stopping you from eating normally.

Exercise and staying active can support weight loss, but it is also important for your heart, muscles, bones, mood and energy levels.

You should aim for at least 150 minutes of moderate activity a week. This can be as simple as taking brisk walks or even going cycling or swimming. It is also recommended to include strengthening activities on at least 2 days a week.

You don’t need to start with intense workouts. If you are new to exercise, regular walks are a good place to begin. You can also build more movement into your day by taking the stairs, standing up more often, doing housework, or gardening.

Strength training can be especially helpful during weight loss because it supports muscle building. This could include weight training, resistance bands, Pilates, yoga, or bodyweight exercises such as squats and lunges.

Mounjaro can cause side effects, especially when you first start treatment or after your dose increases. Common side effects include:

• Nausea
• Vomiting
• Diarrhoea
• Constipation
• Indigestion
• Stomach pain

These side effects can affect your weight in different ways. For example, constipation, bloating, or water retention may make the scales look stuck. Nausea may make it harder to eat balanced meals. Vomiting or diarrhoea can cause dehydration, which may make you feel weak or unwell.

If you are struggling with stomach side effects, it may help to eat smaller meals, eat slowly, avoid very fatty or spicy foods, and regularly drink fluids. Speak to your prescriber if side effects are severe, do not improve, or stop you from eating and drinking normally.

Mounjaro works best when it is taken consistently. If you miss doses, stop and restart, or change your injection day often, your appetite and weight loss progress may be less predictable.

If you miss a dose, follow the instructions in your patient leaflet or ask your pharmacist for advice. Don’t take extra doses to make up for a missed injection. If you regularly forget your dose, try setting a weekly reminder or linking your injection to a routine that you already follow.

Sometimes weight loss is affected by factors outside your diet and activity levels.

Some medicines can make weight loss harder or increase appetite. These may include some antidepressants, antipsychotics, steroids, insulin, and some medicines used for diabetes. Don’t stop taking any prescribed medicine without speaking to a healthcare professional first.

Health conditions can also affect weight. These may include an underactive thyroid, polycystic ovary syndrome, sleep apnoea, menopause symptoms, depression, binge eating disorder, or reduced mobility.

If you are doing everything as advised and still not losing weight, speak to your GP or pharmacist. They can check whether another factor may be affecting your progress.