Why am I not Losing Weight on Mounjaro?

While there are many reasons why your weight loss may slow down or stop while taking Mounjaro, it’s also important to remember that weight loss isn’t a linear process. Having moments during your treatment where you don’t lose weight is a natural part of this process and is called a weight loss plateau. There’s usually a straightforward reason why.

Here, we look at all the different reasons you might not be losing weight with Mounjaro so you can better understand your weight loss journey, and what to do if you’re worried about how your treatment is going.

Brenda Ikeji

Medically reviewed by

Dr Brenda Ikeji

Last reviewed: 23 Oct 2024

How does Mounjaro work for weight loss?

Mounjaro suppresses your appetite and delays the emptying of your stomach to make you feel fuller from less food. The active ingredient, tirzepatide, does this by mimicking 2 naturally occurring hormones in your body known as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones send signals to your brain to let your body know it’s full after eating food.

This is an effective treatment for weight loss as the effects of Mounjaro help you to eat less, so you are much more likely to succeed in your weight loss journey. Due to the way that Mounjaro works, it is more effective when you stick to a healthy diet and exercise plan during your treatment.

Start Your Journey With Mounjaro

How much weight should I be losing with Mounjaro?

While on Mounjaro, you can expect to lose between 16% and 22.5% of your weight over 72 weeks provided you’re responding well to treatment, follow the dosage schedule up to the 5, 10, or 15mg maintenance dose, and stick to a healthy diet and exercise plan.

During these 72 weeks, you’re likely to lose weight at a safe and steady pace, losing a little more weight each month as you change doses and continue your medication until you reach your maintenance dose.

This process usually looks like this:

The monthly results with Mounjaro on different dosages

Remember that people lose weight at different rates, and not everyone responds to treatment in the same way. There is no set amount of weight you should lose. Instead, it’s about losing weight at a pace that works for your body and building healthy and sustainable habits for weight loss that you can maintain long-term.

Reasons you’re not losing weight on Mounjaro

It’s time to change dose

While taking Mounjaro, your dose is slowly increased over time (known as a titrating dosage schedule) so your body gets used to the medication. This gradual increase in dosage is done to avoid any negative side effects. You will eventually reach a maintenance dose, up to the maximum maintenance dose of 15mg.

In studies, people lose more weight on the highest maintenance dose. So if you previously stuck at a lower dose or you’re about to move up a dose, this could be why your weight loss has slowed, especially at the lower doses like 2.5mg. Increase your dose following the schedule and wait and see what happens afterwards. You might find your weight loss gets back on track quickly.

It needs more time to work

We call weight loss a journey because it doesn’t happen overnight. It takes a while for your body to get used to the medication and feel its effects. You also need time to adapt to your new diet and exercise regime before seeing the full impact of all these changes on the scales. And as studies show, the best results are seen up to 72 weeks into treatment (although you’re likely to see changes before this).

We always recommend giving treatment at least 3 months before deciding whether it is right for you and your body. Some people experience weight loss very quickly, while others take a lot more time and dedication. Either way, it’s important to stick with it. If you’re not seeing any results after 3 months and you’re still following healthy lifestyle changes, speak to your doctor.

You need to work on your diet and exercise plan

Weight loss medications help you lose weight, but they don’t do it all on their own. You also need to make healthy changes to your diet and do enough exercise to achieve the best results. If you don’t make the necessary lifestyle changes your doctor has recommended, Mounjaro can stop helping you lose weight.

There’s also a possibility of gaining weight while taking it if you do not follow the correct lifestyle changes. It might be worth looking into your diet and following some healthy recipe meal plans to make sure you’re eating well and not consuming too many calories.

You’re not in a calorie deficit

While taking Mounjaro, it’s important to maintain a calorie deficit for effective weight loss. A calorie deficit is when you consume fewer calories than you burn, causing your body to use its fat energy reserves instead. Over time, this leads to weight gain.

For most people, a calorie deficit is around 600 calories less than they would normally need to consume:

  • Men need around 2,500 calories per day. To stay at an effective calorie deficit, they should eat around 1,900 calories per day.
  • Women need around 2,000 calories per day. To stay at an effective calorie deficit, they should eat around 1,400 calories per day.

Your weight loss might take longer or stop if you’re not eating at a calorie deficit. It’s also important to consider what your calories are made up of. If you eat 2,000 calories a day of unhealthy, saturated fat, even at a deficit, it’s unlikely to have safe and effective weight loss.

You’re stressed

Studies have shown that being chronically stressed can lead to weight gain. This is because it can:

1. Cause hormonal changes

Stress can make your body release hormones that increase your appetite and lower your metabolism. This can lead to craving unhealthy foods and more weight gain from the food you do eat.

2. Make self-control more difficult

When you’re stressed, it’s much harder to find the motivation to exercise and maintain your new, healthier lifestyle. This can lead to weight gain as you become more inactive and are then more likely to eat unhealthy foods. Lowered self-control can also make it harder to stick to your treatment and dosing schedule which is how you’ll find success in your weight loss journey.

3. Release cortisol

Stress triggers your body to release more cortisol, which can cause your body to accumulate more fat.

Stress affects you both physically and mentally, leading to changes in your hormones that directly cause you to gain weight and make it harder to stick to new changes. This can affect your weight loss journey. If you find you’re not losing weight with Mounjaro, and you’re extremely stressed, it might be helpful to look at strategies to better manage stress. You can also get advice and support from your doctor to help lower your stress levels, and they may refer you to a counsellor or therapist.

You need more sleep

If you’re not getting enough sleep, you might also notice a change on the scales. This is because a lack of sleep can affect your hormones, brain function, energy levels, and other factors that contribute to weight gain.

Hormonal changes

Ghrelin – also known as the ‘hunger hormone’. Ghrelin levels increase before eating and decrease after eating. When you don’t get enough sleep, your ghrelin levels don’t decrease as much after eating, resulting in an increase in your appetite.

Leptin – the hormone that makes you feel full. When you don’t sleep enough, your leptin levels go down, so you feel less full and eat more food.

Brain function

When you are sleep-deprived, your frontal lobe is less active. This part of your brain helps with decision-making and impulse control. When it’s less active, it’s harder to make healthier choices or fight food cravings. On top of this, your brain's reward centre is more active when you’re tired, so it’s even easier to make unhealthy decisions when it comes to your diet.

Less energy

When you have less energy, you’re less likely to be active. You're also more likely to crave high-energy foods or more food to help cope with the tiredness.

You have an underlying health condition

Certain health conditions, like thyroid problems and diabetes, can make it harder to lose weight and can even cause weight gain. If you have a condition like this, you should speak to your doctor before starting treatment, as they will adjust your plan with this in mind. They can also help you understand how these conditions might affect your weight loss journey so you can better manage your expectations.

If you start developing new symptoms of a condition while on weight loss treatment, you must speak to your doctor.

You’re taking medication that causes weight gain

Some medications can cause weight gain and make it harder to lose weight, such as insulin, corticosteroids, and antidepressants. If you’re on these medications before starting treatment, your doctor will let you know what to expect.

You should always tell your doctor about any medications you are taking or any changes to your other medications during your treatment with Mounjaro.

You’re in a weight loss plateau

A ‘weight loss plateau’ is when your weight stops changing. You might feel as though you’ve stopped losing weight, or that you’re not seeing many changes all of a sudden. While this can be frustrating, this is an entirely normal part of your weight loss process.

Various things can cause ‘weight loss plateaus’, and they’re usually resolved as you continue treatment or make small changes to your programme. The most common causes of weight loss plateaus are:

Metabolism changes

When you first start losing weight, your metabolism can slow down in an attempt to save energy. When this happens, it can cause a weight loss plateau.

Water weight

When you lose water weight, instead of losing fat you're losing water that your body has been retaining. This happens with a change in diet and exercise for many reasons, such as eating less salt or sweating more often from exercise.

This weight loss often doesn’t last and can be put back on quickly. This can cause a plateau because you think you’ve lost more weight than you have and feel like you’re regaining weight. This is most likely at the start of your journey when you start following a new diet and exercise routine.

Adjusting to your diet

You may hit a weight loss plateau because you’re eating more calories than you need, or those calories are high in saturated fat and other unhealthy nutritional sources. It’s recommended to be strict with your calorie counting until you’re confident you can understand food portion size. Check in with your calories every day and try to stick to a 600-calorie deficit.

You need the right support

Losing weight can be challenging, and it’s a process full of ups and downs that affects both your physical and mental health. Some people find not having the right support system can make it harder to stick to a weight loss routine.

Try to surround yourself with people who understand what you’re working towards, and want to help you and encourage healthy habits. For instance, it can be hard to stick to healthy eating when your friends are only suggesting hangouts that include takeaways or drinking alcohol. Offer some different options and ask your friends to do the same, such as going for a nature walk with a coffee, swimming, or a yoga class.

There are also weight loss support groups where you can find other people going through a similar journey.

You’re dehydrated

Weight loss has been linked to weight gain because it can affect your hormones (slowing metabolism) and cause excess water retention. Studies show that drinking more water can boost your metabolism. It can also help you feel more full, which can reduce snacking, helping you to lose weight more effectively.

It’s also important to stay hydrated to reduce the chance of getting side effects from Mounjaro.

The treatment isn’t right for you

Medications affect everybody differently. Some people find more success with certain treatments than others, and this can come down to medical conditions, medications, or even genetics. In some cases, you may not be losing weight because the treatment you are on just isn’t working for you. And while this is very rare, it can happen.

Your doctor will monitor your journey on Mounjaro and make sure that you’ve lost at least 5% of your body weight after 6 months on your highest tolerated dose. If you haven’t and you’ve been following your other lifestyle changes well, your doctor will look at other treatment options with you.

Are your expectations too high?

Weight loss is a long-term process, and although it’s quite common to see a big drop in weight when you first start a new regime, it takes time to put habits into place to help you lose weight and maintain it.

It does not help to compare or to check the scales every few days. When you feel unmotivated or like you’re not hitting your goals fast enough, try to think about the end goal. Consider how these small changes will make your weight loss a success, and sustainable for the long term. But, don't rush, you will get there if you stick to your programme.

You’re not sticking to your treatment schedule

Mounjaro needs to be injected each week, and you need to increase your dose slowly until you reach a maintenance dose. If you regularly forget to take your treatment or if you take it at the wrong times, this can slow your weight loss down.

Similarly, if you don’t change doses when you need to, it will take longer to reach your maintenance dose, and you may stop losing weight. To get the most out of your treatment, you must stick to your schedule and take Mounjaro as instructed by your doctor.

The only reasons you need to stick to a lower dose are if you’re getting persistent or bothersome side effects, or if you’re happy with your weight loss at the current dose. You can increase your dose again when you’re ready, up to a maximum weekly dose of 15mg, as long as you’ve been on your current dose for 4 weeks.

If you forget to take Mounjaro for over 2 weeks, you’ll need to restart treatment all over again.

How to increase weight loss on Mounjaro

Mounjaro works well when you also make healthy lifestyle and diet changes. Here’s how to increase your weight loss while taking Mounjaro:

1. Stick to a calorie deficit

Eating the same foods and the same amount you ate before taking Mounjaro won’t lead to fast and effective weight loss. By sticking to a calorie deficit of around 600 calories, you can increase how much weight you’re losing with Mounjaro. This is because you’ll be burning a lot more calories than you’re consuming.

2. Stay on top of your doses

Make sure you’re always taking your doses to schedule (every week at the same time) and that you move up a dose when it’s safe for you to do so. Mounjaro is most effective at the 15mg maintenance dose, although 5mg and 10mg can still provide great results.

3. Exercise more

The more you exercise, the more calories you burn. By regularly working out or doing more activity in general, you’ll increase how much weight you lose.

4. Stay hydrated

Dehydration has been linked to weight gain as it can slow down your metabolism and cause you to retain more water. Staying hydrated can prevent this, while also helping you feel fuller and reducing your likelihood of side effects.

5. Eat the right foods

You’ll lose weight faster if the calories you consume have the right nutrients. If your diet is full of sugar and fat, it will take longer to lose weight, even if you’re eating fewer calories. Follow a nutritional plan and speak with your doctor if you need further advice and support on eating the right foods.

What happens when you stop taking Mounjaro?

When you stop taking Mounjaro, you’ll slowly stop feeling the effects of the medication. This means your appetite won’t be suppressed. If you continue to stick to your new, healthier eating habits and regularly exercise, you shouldn’t regain all your weight but there’s a chance that you can regain some.

You may notice that your appetite has decreased as you’ve lost weight and your body has gotten used to eating less food. If you stick with what you’re eating now, rather than what you were eating before, you can slowly get used to eating less even without Mounjaro. It can help to follow a diet plan with lots of protein and fibre to keep you feeling full between meals.

What are Mounjaro alternatives?

Mounjaro is not the only weight loss medication available, and there are plenty of alternatives if it is not right for you. When getting a prescription with us, our doctors will review your consultation to make sure whatever treatment you are on is safe, suitable, and right for your circumstances.

We currently prescribe over 5 different weight loss treatments, including tablets and injections:

Wegovy

Wegovy is an injection treatment just like Mounjaro that needs to be taken once a week. It works similarly by making you feel more full from less food. It’s been proven to work in clinical trials, with patients losing up to 15% of their weight on the 2.4mg dose after 68 weeks.

It’s considered a safe, long-term weight loss treatment. If Mounjaro isn’t right for you, and you’re looking for an alternative injection that works, Wegovy might be the answer.

Saxenda

Saxenda is another weight loss injection, but it needs to be taken every day. Studies found that after 56 weeks on the 3mg maintenance dose, people can lose around 8% of their starting weight.

Like Wegovy and Mounjaro, it works by making you feel fuller from less food. The medication is long-term out of stock, with no word from the manufacturer on when or if it’ll become available again. A generic version of the medication, liraglutide, may be available at some time in the future.

Orlistat and Xenical

Orlistat is an oral tablet and is the generic version of Xenical, the name of the active ingredient both medications contain. These tablets work by stopping your body from absorbing around a third of the fat from meals you eat, which leads to you losing more weight.

They’re taken 3 times a day, after or with each meal that contains fat. They’ve proven to be an effective treatment, with most patients losing at least 5% of their body weight after just 12 weeks. On average, people lose around 1 to 2 pounds (lbs) a week with the help of orlistat or Xenical.

Mysimba

Mysimba is a weight loss tablet that affects the part of your brain that is responsible for hunger and appetite. It can help reduce food cravings and make portion control easier. Mysimba is an effective medication, with most patients losing around 5% of their body weight within 4 months of treatment.

alli

alli contains the active ingredient orlistat and works in the same way – by making your body remove more fat from meals. It is the only over-the-counter, approved weight loss medication available in the UK.

This means you can buy it in your local pharmacy without a prescription or the need to speak to a doctor beforehand. However, you will need to answer some questions for the pharmacist so they can be sure it’s safe and suitable for you.

Conclusion

It's natural to stop losing weight with Mounjaro at some point in your journey, and there are many reasons this can happen. What's most important is being able to identify the cause so you can make a change.

Whether it's your diet, stress levels, exercise routine, or dosage, there'll be an answer somewhere and a straightforward solution to help you get back on track. And remember, if you are worried about your weight loss progress – everyone's journey is different, and people lose weight at different rates.

When you get a prescription for weight loss medication from ZAVA, you will receive a free weight loss support pack with your first order. You can also message a doctor for free through your online account if you’re worried about your weight loss results or need further support.

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

Sources

Water Consumption: Effect on Energy Expenditure and Body Weight Management, National Library of Medicine [accessed 18 October 2024]

Frontal lobe function, sleep loss and fragmented sleep, Sleep Medicine Reviews. Available at ScienceDirect [accessed 18 October 2024]

The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review, PubMed [accessed 18 October 2024]

Increased Hydration Can Be Associated With Weight Loss, National Library of Medicine [accessed 18 October 2024]

Snooze more, eat less? Sleep deprivation may hamper weight control, Harvard Medical School [accessed 18 October 2024]

Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen, emc [accessed 18 October 2024]

Tirzepatide Once Weekly Treatment of Obesity, New England Journal of Medicine [accessed 18 October 2024]

Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen, emc [accessed 18 October 2024]

Xenical, emc [accessed 18 October 2024]

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