How Much Weight Can You Lose on Mounjaro?

Mounjaro is a weight loss injection that contains the active ingredient tirzepatide. It is one of the most effective weight loss treatments with studies showing it can help you lose up to 22.5% of your body weight over 72 weeks. However, the amount of weight you can expect to lose varies based on factors such as your starting weight, diet, and how much you stick to your treatment plan.

In this guide, we’ll break down the potential weight loss you might experience with Mounjaro week by week, what to expect while taking it including the potential side effects, and how you can maximise your results for a successful weight loss journey.

When you first start Mounjaro, you will always begin on the lowest 2.5mg dose, as this will allow your body to get used to the active ingredient tirzepatide. You will also start on this dose if you switch from Wegovy to Mounjaro and have been on 1mg or less per week.

Before you inject Mounjaro for the first time, you’ll need to pick a day and time that’s convenient for you to administer your injections. It’s best to pick a day that you know you’ll be available week after week. Mounjaro works best when it is injected consistently on the same day each week because:

• the medication will remain at a steady level in your bloodstream
• it will help your body adjust to the medication more smoothly, especially as you titrate up the doses, and could minimise side effects

This is the perfect time to consider and implement the lifestyle changes that go hand in hand with your Mounjaro treatment for a successful weight loss journey. We’ll provide you with support materials, such as a weight loss tracker and food diary as part of the weight loss programme from Superdrug Online Doctor. These tools can help you monitor and track your treatment goals and outcomes.

During this period, weight loss is likely to be modest as your appetite decreases.

How much weight can I lose in week 1?

The amount of weight you can lose in week 1 of Mounjaro treatment can vary and will depend on how your body responds to the medication, the lifestyle changes you have made, and other physiological factors, including your age and overall health. One study found that the average weight loss during the first 4 weeks of Mounjaro was 1% of their starting weight.

Some people may notice a sudden loss of weight in the first week, but this could be ‘water weight’. During the first week of treatment, you should have lowered the number of calories you are consuming to move into a calorie deficit. When this happens, your body releases stored glycogen to make up for the missing energy it is used to. With each gram of glycogen being stored with 3g of water, when these stored carbohydrates are released, so is the water, resulting in water loss from the body.

What to expect in week 1 on Mounjaro

Side effects

During the first week, you may also begin to experience some of the common Mounjaro side effects as your body adjusts to the medication, such as:

• feeling or being sick
• headache
• diarrhoea
• constipation
• tummy pain
• weakness or tiredness

These side effects are often mild and can be managed at home. They should start to go away as your body gets used to Mounjaro.

Some of the things you can do to minimise or manage side effects include:

• if you feel sick after injecting Mounjaro, it can help to take your dose in the evening after a meal
• prioritise lean proteins and whole foods when making a diet plan
• eat smaller, more frequent meals to reduce feeling or being sick, think about having 6 smaller meals rather than 3 large meals per day
• stay hydrated by sipping water throughout the day, this can help with sickness, diarrhoea, and constipation

Reduced appetite

You may notice appetite changes in the first week of Mounjaro, but a lot of people won't feel any different at all. It is normal not to have any immediate changes in appetite during the first week of taking Mounjaro, as it can take a short while for the medication to start working.

Week 1 tips

It is unlikely that you will see any noticeable weight loss in the first week, but it is the best time to start setting yourself up for success. Weight loss is a long-term journey, and consistent healthy lifestyle changes are key to making Mounjaro an effective treatment.

Mounjaro week 2 is similar to week 1 because you will still be on the starting 0.25mg dose. You may start to notice the effects of Mounjaro on your appetite becoming more pronounced. You may also start to notice weight loss, though this can vary from person to person.

How much weight can I lose in week 2?

Although some people may start to notice small changes in their weight, it can take several weeks to achieve significant weight loss results - so small changes in the scales are normal at this stage. It’s important that you continue to take Mounjaro injections as prescribed, and follow your diet and exercise plan closely.

What to expect in week 2 on Mounjaro

Side effects

Some people find that their side effects ease as their bodies adjust to tirzepatide, but for others, they can stay the same. If your side effects are difficult to manage or severe, contact your doctor for advice.

Appetite changes

During week 2, many people start to notice a consistent reduction in their appetite and fewer cravings as the medication builds up in their body.

Mounjaro week 2 tips

Now is the perfect time to begin building consistent habits, starting with injection timing. Make sure you always inject Mounjaro on the same day each week to keep the medication at a steady level in your system. It’s also a good opportunity to start focusing on eating smaller, more frequent meals rather than 3 large meals per day, which is what you may have been used to. This will help you prepare for the appetite changes that will happen, even if you are not getting them fully yet.

If you are getting mild Mounjaro side effects, start building things into your routine to help manage them. For example, if constipation is affecting you, start adding some extra fibre into your meals, such as wholegrains, fruits, and vegetables, and take frequent sips of water throughout the day to help encourage regular, softer bowel movements.

By weeks 3 and 4, Mounjaro should be fully active in your system, and you’ll likely start noticing its effects, particularly feeling fuller for longer periods between meals.

After 4 weeks of treatment, one study shows that the average weight loss is around 4%, although this can vary from person to person.

Weeks 3 and 4 tips

At this stage, many people will not see significant weight loss because they are still on the starting dose of Mounjaro, which is designed to help their bodies adjust to the medication. It is important to follow the dosage schedule, maintain consistency when injecting your dose, and continue with your diet and exercise programme to support your weight loss journey. Weight loss is a gradual process and requires patience and determination, even with Mounjaro.

You should continue to focus on eating balanced meals that contain lean proteins, fibre and healthy fats to support your weight loss targets. You should eat even if you do not feel hungry to minimise the chance of nutritional deficiencies.

Continue with your regular exercise plan to build confidence and to start making physical activity a habit. If you’re finding it difficult to stick to your exercise plan, consider changing your activities, exercising with a friend, or joining a group or club if you feel comfortable doing so.

Week 5 is your first dose increase, and you’ll start taking 5mg of Mounjaro every week for the next 4 weeks. At week 8, you can decide if you want to increase to the next dose or remain on 5mg, depending on how you're feeling and how your weight loss is progressing.

How much weight can I lose in weeks 5 to 8?

After 8 weeks of Mounjaro, the average weight loss is around 6%. However, this will depend on the lifestyle changes you have made and if you are sticking to them.

What to expect in weeks 5 to 8 on Mounjaro

Side effects

At this stage, you may experience some side effects returning or worsening as your dose is titrated (gradually increased). These should settle down again once your body gets used to the increased medication.

Appetite changes

With the dose increase, it’s likely that you’ll notice a bigger effect on your appetite. You’ll probably feel fuller for longer after meals, feel you need less food to feel full, and find that you crave snacks less than you used to. All of these things make it easier to manage your calorie intake and help create a calorie deficit.

Exercise tolerance

Now that you have committed to lifestyle changes for a whole month, you may have more energy and feel ready to step up the amount of exercise you are doing or the intensity of your current exercise. However, it is important not to push your body too hard as injuries can slow down your progress.

Weeks 5 to 8 tips

If side effects have reappeared after your dose increase, this is common, and you can manage mild side effects at home with rest, drinking plenty of fluids, and taking over-the-counter painkillers, if needed. However, if you are concerned or find any of the Mounjaro side effects difficult to manage, contact your doctor for advice.

Stick to your diet and exercise plan, as this will become even more important as you increase your doses, and is a key factor in your weight loss journey.

After 8 weeks, if you have tolerated your current Mounjaro dose well, it may be increased to 7.5mg per week. If you are happy with your results on 5mg or you don’t want to increase your dose yet, you don’t have to. Speak to your doctor if you would prefer to stay on your current dose. You can always change your mind later on.

How much weight can I lose in weeks 9 to 12?

During weeks 9 to 12 of Mounjaro, you are likely to start seeing noticeable weight loss results. After 12 weeks of treatment, you can expect to lose up to 8% of your body weight.

What to expect in weeks 9 to 12 on Mounjaro

As your dose increases again, you may see a return of some of the side effects you previously experienced, though this can vary from person to person. Adjusting your diet and lifestyle if side effects occur after a dose increase can help. Try things like:

• eating smaller, more frequent meals
• choosing plain, bland foods, like rice and crackers, and avoiding spicy and greasy foods
• sipping water throughout the day
• taking over-the-counter painkillers to manage headaches
• being patient with your body and allowing it time to adjust by getting rest until you feel better
• distracting yourself with gentle exercise or a hobby you enjoy

You’ll probably start to notice the appetite effects of Mounjaro become stronger during this time. It’s important that you avoid skipping meals, even if you don’t feel hungry. This is because your body needs nutrients, including vitamins and minerals, to avoid nutritional deficiencies and to perform many important tasks.

Why am I not losing weight on Mounjaro in weeks 9 to 12?

There are several reasons why you might not be losing weight on Mounjaro at this stage, including:

1. You’re on a low dose of Mounjaro. The first doses of Mounjaro are designed to help your body get used to the medication, and are not necessarily going to cause significant weight loss. Higher doses of Mounjaro, such as 10mg, 12.5mg, and 15mg, are more effective, and are where you can expect to see the best results.
2. You need to adjust your calorie deficit. As you lose weight, your body will need fewer calories to function – which is known as metabolic adaptation. This means that you need to regularly recalculate how many calories you need to consume to be in a calorie deficit, otherwise your weight loss progress can stall. You can use our free calorie deficit calculator to find out how many calories you should be consuming to lose weight.
3. You’re consuming hidden calories. It’s possible that you are eating more calories than you realise. Keep a food diary to see whether you are snacking, taking on calorie-heavy drinks (fizzy drinks and alcohol), or comfort-eating without realising. All of these things can stall your weight loss progress.
4. You’re not exercising enough. Cutting your calorie intake can make you feel tired or less energetic, which can make it harder to find the motivation to exercise. It’s important to try and stay active, even if it’s only a little bit of exercise a day, to make sure you are burning enough calories to be in a calorie deficit and lose weight.
5. You’re not preserving your muscle mass. Prioritising strength training and eating enough protein is key to healthy weight loss. Muscle burns more calories at rest than fat, so making sure that you are maintaining (or increasing) your muscle mass while on your weight loss journey can help you lose weight more effectively.

For a more in-depth look, you can read our guide on why you might be struggling with weight loss.

Week 13 is when you will increase your Mounjaro dose to 10mg. You’ll keep titrating the dose every 4 weeks until you reach the maximum dose of 15mg in week 21.

The maintenance dose for Mounjaro is 15mg per week, but you may choose to use a lower dose if you find it difficult to tolerate the side effects associated with a high dose, or if you think a lower dose is more effective for you.

How much weight can I lose after week 13?

From week 13 onwards, the weight loss results you can achieve with Mounjaro should become more consistent. By this time, you should be seeing consistent weight loss as you are on the higher, most effective dosages of Mounjaro. By week 20, you can expect to lose approximately 12% of your starting body weight, and long-term use can result in 22.5% weight loss over 72 weeks.

What to expect in week 13 and beyond on Mounjaro

Weight loss

By week 13, you could have lost around 9% of your initial body weight, depending on your individual circumstances. At this stage, as long as you are losing weight, your lifestyle choices and the medication are working for you, but you may still need to wait until you reach the higher doses to notice significant losses.

Side effects

As you increase your dose, some side effects may return until your body gets used to the new strength. Managing them as you have done in the past will be useful.

Medication effect

As your dose increases, the benefits of Mounjaro will become more apparent. You’ll likely feel less hungry, feel fuller faster after eating, and be less likely to snack.

Why am I not losing weight on Mounjaro after week 13?

If you’re not losing weight on Mounjaro, there are several possible reasons why, including:

• you’re still not on the highest therapeutic dose
• you’ve hit a weight loss plateau
• you need to adjust your calorie deficit
• you have underlying health conditions that are hindering your progress
• you need to do more exercise

If you’re on the highest Mounjaro dose, have made all of the necessary lifestyle changes and are still not losing weight, Mounjaro may not be right for you. Speak to your doctor, who may recommend an alternative weight loss medication.

While Mounjaro is highly effective for weight loss, everybody’s weight loss journey looks different which means effects can vary from person to person. The reason for this is several factors can influence how well tirzepatide works for you, including your lifestyle, age, and overall health and wellbeing.

Understanding how these factors can impact your weight loss goals is crucial so you can make adjustments to maximise your success. Below are some of the key factors that can impact your progress with Mounjaro and some tips on how you can address them.

Eating a healthy calorie controlled diet is crucial for maximising your weight loss results with Mounjaro. Your diet should focus on whole, nutrient-dense foods while avoiding processed and convenience/fast foods.

Staying hydrated by drinking plenty of water and clear fluids is important for curbing hunger, supporting your metabolism, and managing side effects like headaches and feeling sick.

Alongside dietary changes, it’s important to establish an exercise routine that works for you and your lifestyle. Ideally, you should aim for at least 150 minutes of moderate intensity exercise each week. Activities such as taking the stairs instead of the lift, and walking to work or the shops can make a real difference and count towards your exercise routine. Other activities include:

• brisk walking
• dancing
• swimming
• gardening
• water aerobics
• fitness classes

Research shows that as we age, our metabolism slows down which can lead to weight gains and an accumulation of body fat.

A slower metabolism can make it harder to lose weight, but be patient and continue making healthier lifestyle choices, including keeping on top of your diet and exercise, this will help increase and maintain the effectiveness of Mounjaro.

Some underlying health conditions can slow your weight loss progress, such as:

• depression
• thyroid disorders
• diabetes
• nutrient deficiencies

How these conditions can affect weight loss vary, and you may need some extra support or to consider extending the time it takes to reach your goals.

However, it isn’t impossible to lose weight if you have an underlying health condition with Mounjaro.Speak to your doctor if you think it is taking you longer than expected to lose weight, they may want to investigate further and find ways they can better support you.

Sleep is important for health. If you do not get enough sleep or find your sleep pattern is broken, it can increase circulating cortisol levels, a hormone linked to stress. It can also negatively affect your metabolism which can lead to weight gain.

You can improve your sleep by practicing good sleep hygiene and trying things like:

• going to bed at the same time each night
• setting an alarm to wake you at the same time each morning
• ensuring your sleep area is clean, tidy, quiet, and cool
• avoiding screens at least 2 hours before going to bed

Stress raises your cortisol levels which can promote fat storage and cause you to eat more food than you need to. You can help to limit your response to stress by identifying your triggers and practicing stress management techniques such as (but not limited to):

• yoga
• meditation
• regular exercise

You may not have reached the Mounjaro maintenance dose yet, which is the most effective dose to help you lose weight. When you begin Mounjaro treatment, you won’t start on this dose. Instead, you’ll begin with a low starting dose and gradually increase it over several weeks to allow your body to get used to the medication until you safely reach your chosen maintenance dose.

Mounjaro can effectively help you lose weight at different dosages. On average, after 72 weeks people who took:

• the 5mg dose lost 16% of their total body weight
• the 10mg dose lost 21.4% of their total body weight
• the highest 15mg dose lost 22.5% of their total body weight

So, if you haven’t lost as much as you would like, it may be that you’ve not reached the effective maintenance dose yet.

Mounjaro isn’t a ‘quick fix’ weight loss medication. Although it can help you to lose up to 22.5% of your starting body weight on the highest maintenance dose, this is supposed to happen gradually over a 72 week period.

Therefore, although Mounjaro will help you lose weight faster than diet and exercise alone, it is still a gradual process. It is also important that you follow and maintain the lifestyle changes necessary to make the most out of your Mounjaro treatment, such as exercising regularly and keeping on top of your healthy diet.

A weight loss plateau happens when you have been steadily losing weight over time and then suddenly stop, even though you’ve made no changes to your lifestyle to halt your weight loss. This is normal and happens to lots of people during their weight loss journey.

There are several reasons why a weight loss plateau can occur. One is that your body goes into survival mode, storing more calories as fat to make sure you have enough in reserve. However, this is usually only a temporary effect of losing weight. Another reason is that you’ve lost water weight but this isn’t fat loss.

If you think you are in a weight loss plateau, you should:

• continue with your Mounjaro treatment
• adjust your diet accordingly
• increase the amount of exercise you’re doing

Weight loss plateaus are normal but if you’re not sure why you may be experiencing one, speak to your doctor for further advice.

If Mounjaro isn’t suitable for you, there are other weight loss medications available including other injections and tablets.

If you're still unsure if Mounjaro is right for you, there are other weight loss injections available which might be more suitable.

Wegovy

Wegovy works in a similar way to Mounjaro because it reduces your appetite, slows digestion and is injected once per week, but it contains the active ingredient semaglutide. It is an effective weight loss medication and can help you to lose up to 21% of your starting body weight after 72 weeks at the highest maintenance dose. You can find out more on the difference between Wegovy and Mounjaro and how to switch from Wegovy to Mounjaro, in our guide.

Liraglutide

Liraglutide is a daily weight loss injection that contains the active ingredient liraglutide. It works in a similar way to Wegovy and Mounjaro and can help you lose on average 8% of your starting body weight after 56 weeks on the highest maintenance dose.

As well as weight loss injections, there are several weight loss pills available. At Superdrug Online Doctor we offer the following:

Wegovy pill

Wegovy pill is an oral tablet that contains semaglutide. It is a GLP-1 receptor agonist that works by reducing your appetite, slowing the time it takes for food to leave your stomach, and regulating your blood sugar levels. Research shows that the average weight loss on the highest daily Wegovy pill dose is 16.6% over 64 weeks.

Orlistat/Xenical

Orlistat, the generic version of Xenical, is a weight loss pill that reduces the amount of fat your body absorbs from the food you eat. It can be taken up to 3 times a day with a meal that contains fat. Instead of being absorbed, the fat leaves your body as stool waste. Research shows that orlistat helps 37% of people lose at least 5% of their initial body weight after 12 weeks.

alli

alli works in exactly the same way as Xenical and orlistat, but it is available at a lower dose and over-the-counter without a prescription.

MySimba

MySimba contains the active ingredients naltrexone and bupropion to help reduce your appetite and suppress food cravings. It’s been shown to help people lose an average of 8.1% of their starting body weight over 56 weeks.

If you are thinking of switching from Mounjaro to any of these weight loss medications, you must consult your doctor for advice.