Why Am I Not Losing Weight on Mounjaro?

Mounjaro (Tirzepatide) has been hailed as a life-changing drug, helping patients lose up to 20% of their body weight. But what if the scale isn’t moving for you? 

It can be frustrating and disheartening not seeing results on medications like Mounjaro. You might even feel like the medication isn’t working. But you’re not alone – and there’s usually a reason why your weight loss has stalled.

So, in this article, you’ll learn why you might not be losing weight on Mounjaro. And we’ll give you tips to help you overcome barriers that prevent progress, so you can get the results you’re looking for.

Why Is Mounjaro Not Working For Me?

If you’re not losing weight on Mounjaro, it’s important to understand that the medication is a tool – not a quick fix.

Like all GLP-1 weight loss medications, Mounjaro can help you lose weight by reducing both your appetite and food noise. However, you’ll only see results if you change your lifestyle too. This means incorporating exercise into your daily routine, changing your relationship to food and your body, and thinking about what to eat on Mounjaro.

While lifestyle is a common reason for stalled progress, there might be other factors at play too – like dosage, underlying health conditions and plateaus.

Be Patient – Mounjaro Takes Time to Work

It can take several weeks for weight loss to occur on Mounjaro. In clinical trials, patients started to lose weight after four weeks of using it. After eight weeks, patients lost 6% of their body weight and after 12 weeks, patients experienced an 8% weight loss.

So if you’ve just started taking Mounjaro and aren’t seeing the results you want, be patient and continue your treatment plan. Focus on successes beyond the scale – like better energy levels and appetite control. This can help keep you motivated.

How fast you lose weight varies from person to person too. Some lose weight quickly while others see gradual changes over time. So try not to compare your progress with anyone else.

Results Will Improve With a Higher Dose

Lower doses may not suppress your appetite enough to produce results. So if you’re not seeing significant weight loss on these doses, don’t worry – it’s completely normal.

You’ll typically start Mounjaro on the lowest dose (2.5 mg), before increasing to 5 mg after four weeks. This gradual approach (titration) gives it time for your body to adjust to the medication. It keeps you safe and makes sure the treatment is as effective as possible. 

As your dose increases, you’ll notice the effects of Mounjaro more. Reaching the highest dose you can tolerate will help you reach your weight loss goal, as shown in clinical trials. After 72 weeks, patient lost:

• 16% average body weight loss on a 5 mg dose
• 21.4% average body weight loss on a 10 mg dose
• 22.5% average body weight loss on a 15 mg dose

Are You Skipping or Misusing Doses?

Regularly missing doses or splitting your Mounjaro dose into smaller amounts than advised (also known as ‘microdosing’) can make the treatment less effective. It is also unsafe and can increase your risk of serious side effects.

We recommend you stick to the dosing schedule your prescriber has given you. This will make sure the treatment is as effective as possible. You should inject the dose on the same day and at the same time each week. Setting a reminder on your phone can help you remember to take it.

Your Diet Might Be Slowing Your Progress

Mounjaro helps suppress your appetite. But you won’t lose weight if you’re still consuming more than your body needs. Focus on eating a balanced, nutrient-dense diet made up of whole foods and be mindful of portion sizes.  

While eating fewer calories contributes to weight loss, don’t focus on the calorie deficit. Instead, focus on getting the best nutrition from the food you eat. Nurturing a healthy relationship with food will contribute to a healthy lifestyle. 

If you find emotions trigger a craving to comfort eat, it can feel a little overwhelming. The key here is to reframe your thinking. Strategies like mindfulness, deep breathing or yoga can help you manage unpleasant feelings, like stress, boredom or sadness. These are common triggers for comfort eating.

Your Activity Level Needs a Boost

Living a sedentary lifestyle will slow your progress, so it’s important to exercise when you take Mounjaro too. Exercise supports weight loss by helping you burn fat and boost your metabolism. It also lowers your stress levels, improves wellbeing, and cuts your risk of developing serious health conditions.

If you’re new to exercise, aim for 30 minutes of physical activities each day. Look for simple ways to stay active throughout your day, like walking to the shops instead of driving or taking the stairs instead of the lift.

As you gradually build your stamina, it may help to step things up a little. For example, by adding some strength training into your routine. This will help you build and retain muscle mass, which has an extra fat burning effect.

If you’re not quite ready – or able – to jog or run, pick up the pace on a brisk walk for 10-20 minutes. This will help circulation and contribute to your recommended 150 minutes of weekly exercise.  

You’ve Hit a Weight Loss Plateau

Weight loss plateaus occur when your body adapts to a routine, like a new diet or exercise habits. This causes your progress to slow and even stop. While frustrating, it’s common and simple changes can help restart your stalled progress.

Increasing your protein intake and incorporating a balanced approach to carbohydrates can help your progress. Exercising more and managing stress can also help break the plateau.

However, a Mounjaro plateau could be a sign your current dose is too low. Talk to your prescriber as adjusting your dose might help get you back on track.

You Have Other Health Conditions

Health conditions that impact metabolism or hormone levels, like hypothyroidism or PCOS, weight loss can be more challenging. Some medications such as antidepressants and corticosteroids can also impact your weight.

Speak with a doctor if you suspect an underlying health issue could be hindering your weight loss. They can assess you and organise tests to determine whether it’s affecting your progress. And they can then advise you on next steps.

Mounjaro Might Not Be Right For You

Although rare, there are cases where Mounjaro isn’t right for a patient. At Simple, we advise patients should lose at least 5% of their body weight within the first six months of treatment. If you don’t meet this target, we’ll discuss whether to continue on Mounjaro.

Other weight-loss medications may be an option if you think the treatment isn’t working for you. Popular alternatives include:

• Wegovy (semaglutide): As a GLP-1 receptor agonist, Wegovy works similarly to Mounjaro but has a different active ingredient. In one study, patients lost on average 15% of their body weight after 68 weeks.
• Saxenda (liraglutide): Another GLP-1 receptor agonist, but with a different active ingredient to Mounjaro and Wegovy.
• Orlistat (Alli, Xenical): Orlistat comes in tablet form and has a completely different mechanism of action to Mounjaro and GLP-1 injections. You take it after each meal and it reduces the amount of fat you absorb from food by up to 33%.

If you’re thinking about switching, discuss your plans with your healthcare provider first. They’ll work with you to determine whether a different medication will be better for you. If you’re a patient with us, call our team on 0141 774 5023.

Aim For Sustainable Weight Loss, Not Quick Fixes

It is important not to get too caught up in the idea of rapid weight loss while on Mounjaro. Healthy weight loss is slower and more sustainable. So aim for a steady weight loss of 1-2 lbs per week.

Patients who combine Mounjaro with a balanced diet, lifestyle changes and regular exercise will see the best long-term results. That’s why we don’t just prescribe you medication – we offer tailored health advice to support you throughout your journey.

And remember the number on the scale is not the only measurement of success when on a weight loss journey. Make sure to celebrate the non-scale victories too, including higher energy levels, better-fitting clothes and a healthier relationship with food.

Key Takeaways

• Mounjaro is a Tool, Not a Magic Solution: While this medication can help regulate appetite and metabolism, it is most effective when combined with healthy eating habits and regular exercise.
• Finding the Right Dose is Crucial: Not everyone responds to the same dosage, and some people may need a higher amount before they experience significant weight loss.
• Your Diet and Exercise Levels Could be Impacting Weight Loss: Eat nutrient-dense foods and avoiding excessive processed foods, sugars, and unhealthy fats. Aim for 30 minutes of movement each day and make small changes, like walking more.
• Medical Conditions Can Affect Your Weight Loss: If weight loss is slow despite your best efforts, underlying health issues or medications may be a factor. Consult your doctor to address any concerns.
• Sustainable Weight Loss Requires Patience and Consistency: Expecting rapid weight loss can cause frustration, but steady progress over time is the key to long-term success.

Clinically reviewed by: Richard Wood, GPhC reg: 2078802

Diet advice reviewed by: Laura Perez, British Dietetic Association membership no: 24597

References 

Fardet, L., Nazareth, I., Petersen, I., 2021. Long-term systemic glucocorticoid therapy and weight gain: a population-based cohort study. Rheumatology (Oxford). 60(3), pp.1502-1511. [online]. Available from: https://pubmed.ncbi.nlm.nih.gov/32864693/

Jastreboff, AM., Aronne, LJ., Ahmad, NN., Sean Wharton, MPH., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, MJ., Stefanski, A., 2022. Tirzepatide Once Weekly for the Treatment of Obesity. The New England Journal of Medicine. 387, pp.205-216. [online]. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038  

Sarwan, G., Daley, SF., Rehman, A., 2024. Management of Weight Loss Plateau. StatPearls. [online]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK576400/

Healthline. (2017). 14 Simple Ways to Break Through a Weight Loss Plateau. [online] Available at: https://www.healthline.com/nutrition/weight-loss-plateau 

NHS, 2023. Physical activity guidelines for adults aged 19 to 64. [online] NHS. Available at: https://www.nhs.uk/live-well/exercise/physical-activity-guidelines-for-adults-aged-19-to-64/ [Accessed 15 Apr. 2025].

www.medicines.org.uk. (n.d.). Mounjaro KwikPen 10mg solution for injection in pre-filled pen – Summary of Product Characteristics (SmPC) – (emc). [online] Available at: https://www.medicines.org.uk/emc/product/15484/smpc 

NHS (2021). Underactive thyroid (hypothyroidism). [online] NHS. Available at: https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/ 

NHS (2022). Polycystic Ovary Syndrome. [online] NHS. Available at: https://www.nhs.uk/conditions/polycystic-ovary-syndrome-pcos/ 

Petimar, J., Young, JG., Yu, H., Rifas-Shiman, SL., Daley, MF., Heerman, WJ., Janicke, DM., Schuyler Jones, W,m Lewis, KH., Lin, PI., Prentice, C., Merriman, JW., Toh, S., Block, J., 2024. Medication-Induced Weight Change Across Common Antidepressant Treatments: A Target Trial Emulation Study. Annals of Internal Medicine. 177(8). [online]. Available from: https://www.acpjournals.org/doi/10.7326/M23-2742 

Wilding, J.P.H., Batterham, R.L. and Calanna, S. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine, [online] 384(11), pp.989–1002. doi:https://doi.org/10.1056/NEJMoa2032183.