Mounjaro for Weight Loss: How Does It Work?
Weight loss is a journey that requires time, effort, and dedication. While some people see results with diet and exercise alone, others may need additional help.
Mounjaro is a type of specialist weight loss medication that’s available to provide extra support when a healthy lifestyle just isn’t enough. Indeed, research has shown that pairing this treatment with making positive changes can result in considerable improvements and some impressive transformations.
If you think you could benefit from adding medication to your regime, you’ll probably want to know more about Mounjaro for weight loss and just how it can help you reach your goals. We cover all of this and more in this handy guide, so let’s get started.
Mounjaro: What is it Used For?
Mounjaro is a weekly self-administered prescription-only injection that has been licensed for weight loss and type 2 diabetes in the UK. When combined with healthy lifestyle changes such as an improved diet and regular exercise, it can improve blood sugar levels and help people feel fuller for longer — thereby reducing food and calorie intake.
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People wanting to take Mounjaro for weight loss purposes need to meet strict eligibility criteria, which are:
- a body mass index (BMI) of 30 or above, or
- a BMI of at least 27 and at least one weight-related health condition like high blood pressure or type 2 diabetes
Mounjaro is available on private prescription through trusted providers like Prescription Doctor, and has also been approved by the National Institute for Health and Care Excellence (NICE) for use on the NHS.
How Does Mounjaro Work for Weight Loss?
Mounjaro’s active ingredient, tirzepatide, mimics the actions of two digestive hormones called glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). By attaching to the GLP-1 and GIP receptors in the brain, Mounjaro controls your hunger and blood sugar levels, making it an effective weight loss medication.
Mounjaro supports weight loss by:
- Reducing food intake
- Slowing down the time it takes for food to pass through your stomach
- Keeping you feeling fuller for longer
As your Mounjaro treatment increases, you will notice that you feel satisfied with smaller meals, resulting in the consumption of fewer calories. This is called a calorie deficit, and this, combined with the other benefits of Mounjaro, is what encourages weight loss.
Mounjaro
- Approved Weight Loss Treatment
- Suitable for adults with a BMI of +30kg/m²
- Pre-filled injection pen
Mounjaro also triggers the release of insulin from your pancreas to help control high blood glucose levels in type 2 diabetes patients. In obesity, the body may not always respond to insulin as expected, causing blood sugar fluctuations that can cause spikes and crashes, leading to food cravings, hunger, and low energy.
By improving the body’s response to insulin, Mounjaro encourages cells to take up the sugar in your blood and use it for energy, keeping glucose levels balanced. In turn, this prevents energy crashes, low mood, overeating, and weight gain.
What is the Average Weight Loss on Mounjaro?
According to clinical trials, Mounjaro can help you lose up to 22.5% of your starting body weight at the highest maintenance dose of 15 mg per week over 72 weeks. However, your weight loss with Mounjaro will depend on several factors, which means you may lose more or less than the averages reported in clinical trials.
In a study comparing the effectiveness of the active ingredients in Mounjaro and Wegovy for weight loss, the average weight loss was greater in the tirzepatide (Mounjaro) group (15.3%) than the semaglutide (Wegovy) group (8.3%) after 12 months.
The SURMOUNT-1 trial investigated the effectiveness and safety of Mounjaro’s active ingredient for weight loss in obese people. The researchers found the following:
Tirzepatide (5 mg) | Tirzepatide (10 mg) | Tirzepatide (15mg) | Placebo | |
|---|---|---|---|---|
| Body weight change from baseline (%) | -16% | -21.4% | -22.5% | -2.4% |
| People achieving ≥ 5% weight loss (%) | 89.4 | 96.2 | 96.3 | 27.9 |
| People achieving ≥ 10% weight loss (%) | 73.4 | 85.9 | 90.1 | 13.5 |
| People achieving ≥ 15% weight loss (%) | 50.2 | 73.6 | 78.2 | 6.0 |
| People achieving ≥ 20% weight loss (%) | 31.6 | 55.5 | 62.9 | 1.3 |
Mounjaro works best alongside a calorie-controlled diet and regular exercise. It’s also important to remember that everyone is different, and your personal weight loss results may differ.
What Can Impact Mounjaro Weight Loss Results?
Taking Mounjaro for weight loss isn’t a quick fix or a miracle solution, and several factors can impact your journey and the time it takes to reach your weight loss goals. Some of the factors that can impact Mounjaro weight loss results are:
- Diet: For the best results with Mounjaro, you’ll need to eat a calorie-controlled diet. A 600-calorie deficit is the best way to encourage safe weight loss, but you can build up to this by reducing your calorie intake by 100 to 200 calories a week until you reach this. Focus on whole foods, like fruit, vegetables, and wholegrains, alongside lean proteins when planning meals.
- Exercise: Regular physical activity will help you burn off excess calories. The more active you are, the more calories you’ll burn, and the greater your weight loss will be.
- Age: As we age, it can get harder to lose weight because our metabolism slows down and hormone levels change. You may also find you are less active than when you were younger. However, try to be as active as possible while using Mounjaro for weight loss. Set small targets and gradually increase them as your journey progresses.
- Underlying Health Conditions: Some health conditions can make weight loss more difficult. If you have an underlying health condition, like type 2 diabetes, an underactive thyroid, or a hormonal imbalance, let the clinician know before you start treatment. Treating the underlying condition appropriately will aid your weight loss journey.
How to Use the Mounjaro Kwikpen
Mounjaro is administered using the Kwikpen, a disposable and easy-to-use device that’s designed to last for four doses. The injections are delivered subcutaneously, inside the layer of fat and connective tissue just under the skin. There are several sites on the body which can be used and rotated between to avoid irritation.
The main Mounjaro injection sites are:
- Stomach: Be sure to stay at least two inches away from your belly button
- Upper arm: Dose should be administered on the back of your arm. You may need somebody to do this for you
- Thigh: Choose a different point on your thigh each time to reduce the risk of scar tissue developing
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Each administration of Mounjaro delivers 0.6 ml of medication into the body, regardless of the dose you are currently taking. Once the Kwikpen has been used all four times, you can safely dispose of it and start a new one.
You can learn more about how to use the Mounjaro injection pen in our guide.
What is the Most Effective Dose of Mounjaro?
Clinical studies have shown that the most effective dose of Mounjaro for weight loss is 15 mg, which is the maximum strength you can take. However, it is still possible to achieve significant weight loss with lower doses — with 10 mg also being a common maintenance level.
Mounjaro doses are delivered according to a set schedule, which has been developed for maximum efficacy. Remember that everyone’s journey is different, so you may not need to follow this regime exactly to achieve your goals. If you are achieving meaningful weight loss on a lower dose, your clinician may advise against upping it.
Real Weight Loss Results on Mounjaro
It’s all well and good regurgitating the results of clinical trials when explaining the effectiveness of Mounjaro for weight loss, however, nothing hits home more than some real-life examples of how the medication has helped people on their journey. Well, that’s just what we can provide.
You can check out these real before and after stories of people sharing their weight loss results on Mounjaro and read about their life-changing transformations. Whether it’s shedding pounds, improving their metabolic health, and gaining confidence in themselves, hopefully their success can inspire you to achieve your goals.
Mounjaro or Wegovy: Which is Better?
Although both treatments can deliver positive results, Mounjaro is considered to be more effective for weight loss than Wegovy. Studies have shown that a higher percentage of participants lost 5% or more of their body weight over 72 weeks on the highest dose of Mounjaro than those on the Wegovy maintenance dose.
Wegovy
- Approved Weight Loss treatment
- Weekly injection
- Reduces risk of heart attack & stroke
While Mounjaro targets both the GLP-1 and GIP hormones, Wegovy only works on GLP-1 — limiting its potential impact. However, this doesn’t automatically mean that Wegovy should be ruled out completely. Everyone’s path to weight loss is different, so it’s important to carefully compare both options to determine which one is right for you.
What’s Better: Mounjaro or Ozempic?
Mounjaro is the better option for weight loss when compared to Ozempic. Despite both treatments being GLP-1 receptor agonists, only Mounjaro is licensed for use in this way. Ozempic, meanwhile, should be administered to help manage high blood sugar levels.
Mounjaro
- Approved Weight Loss Treatment
- Suitable for adults with a BMI of +30kg/m²
- Pre-filled injection pen
It’s recommended that you only take medication for its intended purpose, so although Ozempic is sometimes prescribed “off-label” for weight management, we wouldn’t consider it to be a viable option. You can find out more information about these two injections in our comparison guide.
Other Alternatives to Mounjaro
Despite its efficacy for weight loss, Mounjaro may not be suitable for everyone. It could be incompatible with certain health conditions or medication, or you might feel uncomfortable with needles or injections. Whatever your reasoning, other treatments are available, including MySimba, orlistat, and alli. Each has its benefits and drawbacks, so it’s important to research which is better for you.
Here are the main alternatives to Mounjaro in a bit more detail:
- MySimba: A prescription-only weight loss pill that contains two active ingredients, naltrexone and bupropion, that work by suppressing your appetite. After 56 weeks, the average weight loss with MySimba was 8.1%.
- orlistat: A fat absorption blocking weight loss pill that’s also available under the brand name Xenical, orlistat can be taken up to three times a day with fat-containing meals. Studies have shown that it helped 37% of people lose at least 5% of their total body weight after 12 weeks, compared to 19% given a placebo.
- alli: An over-the-counter version of orlistat that is available without a prescription because it contains a lower dose of the active ingredient.
- Saxenda: A once-daily weight loss injection that contains the active ingredient, liraglutide and works by mimicking the actions of GLP-1. Saxenda is currently unavailable.
Start Your Mounjaro Weight Loss Journey with Prescription Doctor
If you feel like you’d benefit from adding Mounjaro to your weight loss regime, Prescription Doctor is here to help. We’ll provide you with all the support and guidance you need, so you can proceed with complete confidence.
Simply complete our simple questionnaire and our clinicians will determine the suitability of Mounjaro for weight loss when compared to your own personal circumstances, or recommend an alternative treatment. We’ll then deliver your medication, sometimes the very next day, in plain packaging.
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Since our inception in 2013, we’ve supported a large number of people just like you and helped them reach their goals. Our dispensing pharmacy is fully-regulated by the General Pharmaceutical Council (GPhC), so you know you’re working with a provider you can trust.
Are you ready to embark on your journey to better health? Start your Mounjaro weight loss consultation today.
Sources
- emc, (2025). Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen.
- emc, (2024). Wegovy 2.4 mg, FlexTouch solution for injection in pre-filled pen.
- emc, (2023). Mysimba 8 mg/90 mg prolonged-release tablets
- emc. (2023). Xenical 120 mg hard capsules
- JAMA, (2024). Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity
- Lancet, (2023). Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial
- NEJM, (2022). Tirzepatide Once Weekly for the Treatment of Obesity.
- NEJM, (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity
Authored By
Leanne Edermaniger
Medical Content WriterPublished on: 11/06/2024
Reviewed By
Mohamed Imran Lakhi
MPharm - Lead PharmacistReviewed on: 08/04/2025
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