How Much Weight Can You Lose in a Month with Mounjaro?
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When it comes to weight loss, Mounjaro is one of the most popular and effective treatments available. In clinical trials, its active ingredient, tirzepatide, can help people shed up to 22.5% of their starting body weight. However, for many people considering embarking on their Mounjaro journey, understanding how the weight loss injection can help them within the first month and beyond is equally important as the end result.
So, if you’re wondering, “How much weight can you lose in a month with Mounjaro?”, look no further than this dedicated guide. We’ll delve into what your first four weeks on the medication could look like, how the treatment works, and answer some of the most frequently asked questions to help you make a more informed decision about whether Mounjaro is right for you.
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Is Mounjaro Effective for Weight Loss?
Unlike most weight loss injections, Mounjaro works by mimicking two digestive hormones within the body, known as gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Meanwhile, treatments like Wegovy and Nevolat only focus on GLP-1. It’s this dual action of Mounjaro that makes it the most effective medication of its kind to date.
Clinical trials have supported this finding, with one reporting that 42% of Mounjaro users achieved at least a 15% weight reduction after one year, compared to 18% of Wegovy users. Meanwhile, another study compared the impact of tirzepatide (Mounjaro), semaglutide (Wegovy), and liraglutide (Nevolat), with the average weight loss for each treatment being:
- 5% for liraglutide
- 12% for semaglutide
- 18% for tirzepatide
While clinical data is all well and good, if you’re thinking about taking Mounjaro, you’ll likely want to see some real-world examples of how effective the medication can be. Well, look no further than these impressive before-and-after stories, or genuine reviews from our customers. We’re sure that all of this combined will show you just how effective Mounjaro can be.
Mounjaro: How it Works for Weight Loss
Mounjaro’s active ingredient, tirzepatide, supports weight loss by binding to the body’s GLP-1 and GIP receptors. In doing so, it helps to:
- Suppress your appetite
- Reduce food cravings
- Slow down stomach emptying
- Regulate blood sugar levels
Mounjaro is most effective when it is paired with a diet plan and exercise programme. Although Mounjaro reduces appetite and regulates how your body processes food, incorporating a balanced diet alongside physical activity maximises Mounjaro’s weight loss potential and boosts your overall wellbeing.
So, now that we’ve covered how effective the treatment is and how it works, what could your first few weeks on the medication look like? Just how much weight can you lose in a month with Mounjaro? Let’s take a look.
How Much Weight Can You Lose in a Month with Mounjaro?
Mounjaro gets to work after your first injection, with some people noticing changes in appetite within a few days. Weight loss at this early stage will usually be minimal, though you could start to see subtle changes within the first month. To give yourself the best chances of success at this time, it’s important that you make lasting lifestyle changes and stick to the dosage schedule as closely as possible.
It’s important to remember, however, that everyone’s journey is unique. If you’re feeling that it’s taking you longer to spot the stages of weight loss or are concerned that the medication may not be working for you, it’s important not to worry. Focus instead on the little things, such as increased energy levels, your clothes becoming baggier, or enhanced motivation. All of these can serve as useful tools to keep you on track.
With this in mind, let’s take a look at what one month on Mounjaro might look like and how much weight you could lose.
Mounjaro
- Approved Weight Loss Treatment
- Suitable for adults with a BMI of +30kg/m²
- Pre-filled injection pen
Mounjaro First Week Weight Loss
Mounjaro is intended to be a long-term solution rather than a miracle cure, so it’s unlikely that you’ll notice any significant weight changes in this first week. That being said, studies have shown you could lose around 1% of your body weight each week during the first month. This is not guaranteed and will vary from person to person.
Instead of focusing on weight loss during the first week, it’s a good idea to establish the foundations of your treatment routine. Mounjaro is most effective when taken on the same day and at the same time, so it’s important to create a schedule you can stick to. If you’re wondering about the best time to take Mounjaro, our dedicated guide can help.
Your first dose is also a good opportunity to monitor how your body responds to tirzepatide and note any side effects you experience, such as nausea, diarrhoea, or constipation. These factors may influence your decision on when to take Mounjaro moving forward. Some people, for example, prefer taking it first thing in the morning to monitor the effects, while others opt for the evening to sleep through them.
During this week, you may also start to make some changes to your lifestyle, including your diet and activity levels. If you’re wondering what you should eat on Mounjaro and the types of food to avoid, we’re here to help.
Second Week on Mounjaro: What to Expect
After your second shot of 2.5 mg – Mounjaro’s lowest dose – it’s crucial to continue monitoring any side effects you might be experiencing. Most mild effects will improve as your body gets used to tirzepatide and can be managed at home in the following ways:
- Feeling or being sick or having diarrhoea: Eat smaller, more frequent meals, try eating plain foods like rice or toast, and avoid greasy, fatty, and spicy meals. Drink plenty of water to keep yourself hydrated.
- Headaches: Drink plenty of water and consider taking over-the-counter painkillers, such as paracetamol and ibuprofen.
- Constipation: Increase the amount of fibre in your diet and drink plenty of water to help bulk up your stools. Speak to your clinician or pharmacist about over-the-counter constipation remedies.
- Injection site reactions: Rotate your injection site each week to limit irritation. Use our detailed guides to learn how to use Mounjaro and where to administer it.
Weight loss during week 2 is still unlikely to be significant. Remember, you’re only expected to have dropped around 2% of your body weight at this point, if that. You may instead notice that your appetite is reducing, you’re experiencing fewer cravings, and you are starting to feel fuller for longer, so draw upon these positives as you move into week 3.
Mounjaro Third Week Results
Your third week on Mounjaro could yield a 3% total drop from your starting body weight. However, the real results lie with the impact the treatment has on your body now that medication levels are stabilising. Side effects should have subsided, and you’re likely to find it easier to follow your diet and exercise regimen.
Even if you’re not feeling hungry, it's important to continue eating and maintaining your calorie deficit so you don’t risk nutritional deficiencies. You may also want to consider adding vitamins and supplements to your routine.
Average Weight Loss on Mounjaro: First Month Results
By week 4 of Mounjaro, it’s possible that you could have lost an average of 4% of your starting body weight. However, your actual result will depend on several factors, such as how well you’re following your diet and exercise plan and whether the medication is suitable for you.
At this point, you should also have a good idea of how well your body is tolerating Mounjaro and whether you’re ready to move up to the next dose. If you have any concerns or queries, it’s a good idea to speak to your clinician before increasing your dosage.
What are the Long-Term Effects of Mounjaro?
Mounjaro isn’t a quick-fix solution and is intended for long-term use to help you initiate and then maintain weight loss. Clinical trials have investigated the effects of Mounjaro over 2 years and found that weight loss plateaued after around one year but was maintained for 18 months to 2 years. It also found that tirzepatide is both well-tolerated and has a safety profile that is similar to other GLP-1 receptor agonists, such as Wegovy and Nevolat.
Although in the first 4 weeks, weight loss may not be so noticeable, Mounjaro weight loss after 3 months should be more significant, with some studies reporting an average 8% weight reduction on the 5, 10, or 15mg dose. Don’t worry if you’ve lost more or less at this point; these are just averages, and your weight loss journey will be unique to you. However, in most cases, if you haven’t achieved at least a 5% weight reduction in 12 weeks, your clinician may tell you to stop taking Mounjaro and recommend an alternative weight loss treatment. That’s because it’s unlikely to be beneficial for you if you haven’t seen any progress so far.
Mounjaro weight loss will take time, and it is important to be patient with yourself and the medication. Our week-by-week weight loss guide can help you track what to expect as you begin your journey, adjust your doses, and determine if you’re on target to meet your weight loss goals.
What Can Impact Weight Loss on Mounjaro?
Mounjaro is just one piece of the puzzle when it comes to losing weight; you’ll need to pair it with a healthy lifestyle to achieve its full benefits. However, if you are not losing as much weight as you would like on Mounjaro, then there could be several reasons for this, including:
- You need more time: Patience is key, especially when you first start a new treatment. It can take up to 12 weeks to lose 5% of your starting body weight, so it is important to give Mounjaro sufficient time to show results.
- You haven’t reached the maintenance dose yet: If you follow the Mounjaro dosage guide correctly, it can take 21 weeks to reach the maximum 15 mg dose. This is the strength that is associated with the greatest average weight loss.
- You’re not in a calorie deficit: A key factor for losing weight is maintaining a calorie deficit. That is, eating fewer calories than you burn.
- Other medications could be hindering weight loss: Having other health conditions or taking other medications can impact your ability to lose weight.
- You need to exercise more: The more you move, the more energy you will burn, and the more likely you will be in a calorie deficit.
Frequently Asked Questions
Whether you’re just starting out on Mounjaro or you’re weighing up your options, perhaps even deciding which is better, Mounjaro vs Wegovy, you’re bound to have some unanswered questions. Here we address some of the most frequently asked questions about Mounjaro to help you make the right decision for you.
How to Get Mounjaro Privately?
Although Mounjaro is now available on the NHS, the wait times are long, and those who are most in need will be prioritised. To relieve some of this burden, Mounjaro can be obtained on a private prescription via online pharmacies, like Prescription Doctor, and private clinics.
When buying Mounjaro privately, there are a few things you should consider, including choosing a reputable and trusted company, avoiding counterfeit medications, and ensuring your data is protected at all times. You can find out more in our expert guide: How to Buy Mounjaro Online: 6 Top Tips.
Mounjaro
- Approved Weight Loss Treatment
- Suitable for adults with a BMI of +30kg/m²
- Pre-filled injection pen
Mounjaro: How to Use the Pen?
Mounjaro is a self-injectable weight loss medication that is provided in a KwikPen device. Each pen contains 4 doses, so it will last for 4 weeks. You will need to attach a new needle each time you use the pen, but it has been designed to be easy to use and inject yourself without any help.
Mounjaro can be injected in your stomach, upper thigh, or upper arm, and you should rotate the injection site each time you take it to lower the chance of irritation. Check out our ‘how to inject Mounjaro safely’ guide for more detailed instructions.
How to Get the Most Out of Mounjaro?
You can enhance the effectiveness of Mounjaro by applying some simple tips and tricks to your everyday routine. These include:
- Following the dosage schedule exactly (where possible)
- Reducing your calorie intake and increasing your calorie burn (exercise)
- Limiting your exposure to stress
- Getting a good, restful night’s sleep
- Listening to your body
Mounjaro works best alongside a healthy lifestyle, and the changes you make can help you maintain your weight loss after your treatment ends.
How Long Does it Take for Mounjaro Side Effects to Start?
Most people notice that their Mounjaro side effects start soon after their first injection or when they increase their dose every 4 weeks. However, they usually get better on their own as your body adjusts to the medication, but how long they last will depend on your body.
If you get any side effects that concern you or you find it difficult to manage, speak to your clinician, who can advise you on what you should do. They may even recommend an alternative weight loss injection or pill if they think you will tolerate it better.
How to Store Mounjaro Once Opened
After you have used your Mounjaro KwikPen for the first time, you can either store it in the fridge at (2°C to 8°C) or at room temperature, as long as it does not go above 30°C for up to 30 days. However, this may differ if you decide to travel with Mounjaro.
It’s also important that you store your pens out of reach of pets and children, and that you keep them away from direct heat and sunlight, as this may impact their effectiveness.
Mounjaro + Prescription Doctor = Weight Loss Success
As well as diet and exercise changes, there’s also another crucial factor you need to consider when starting your Mounjaro journey, and that’s your weight loss partner. At Prescription Doctor, we’ve been committed to helping people just like you positively transform their lives in a safe and effective manner since 2013.
Our clinicians are experts in their field and are qualified to assess our patients on a case-by-case basis to ensure the medication they choose is safe and suitable for them to take. But our support doesn't stop there. With regular check-ins and access to a library of informative content, including meal plans, what to expect week by week, and guidance on addressing side effects, you can be confident that you’re in safe hands.
We understand that deciding to use weight loss injections is a significant step, which is why we want to provide you with as clear an understanding of what to expect as possible. From answering questions such as ‘How much weight can you lose in a month with Mounjaro?’ to discussing potential weight loss results after three months or even over an extended period, we’re committed to helping you make an informed decision about your medication.
Start your Mounjaro weight loss consultation today and take a step closer to a new you.
Sources
- EMC (2025): Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen.
- JAMA (2024): Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity.
- NEJM (2022): Tirzepatide Once Weekly for the Treatment of Obesity.
- PubMed (2024): Glucagon-like Receptor-1 agonists for obesity: Weight loss outcomes, tolerability, side effects, and risks.
Authored By
Leanne Edermaniger
Medical Content WriterPublished on: 21/06/2024 Re-Published on: 11/09/2025
Reviewed By
Mohamed Imran Lakhi
MPharm - Lead PharmacistReviewed on: 11/09/2025
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