Not Losing Weight on Mounjaro? 7 Possible Reasons Why

Mounjaro (tirzepatide) is a prescription-only weight loss injection that mimics the effects of 2 digestive hormones to regulate your appetite, improve insulin sensitivity, and support weight loss. Clinical trials have shown that it can help you lose an average 22.5% of your starting body weight once you get to the maximum 15mg dose after 72 weeks.

However, not everyone sees rapid or dramatic results. If you’re currently taking Mounjaro and not losing weight as expected, you’re not alone. Many people go through temporary plateaus or slowed progress, which is a normal part of a weight loss journey with or without medication, and can often be corrected with a few changes and time.

In this guide, we explore why you might not be losing weight on Mounjaro and what you can do about it.

Mounjaro is a dual action receptor agonist that targets both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors. This means Mounjaro binds to these receptors, mimicking the hormones and causing the same effects.

By mimicking these hormones, Mounjaro’s active ingredient, tirzepatide, helps to:

• reduce your appetite
• increase feelings of fullness
• slow down stomach emptying
• improve insulin sensitivity and reduce blood sugar spikes

These actions combined make it easier for you to follow a healthy, balanced diet, including a calorie deficit, which will help you to lose weight and keep it off. This must be combined with increased exercise.

While Mounjaro reduces your appetite, it does not cause weight loss directly, and you must make these changes to get the best results.

How quickly does Mounjaro work?

Some people start to notice changes in their appetite almost straight away, but it can take up to 12 weeks to notice significant changes to your body and appearance.

When you first start Mounjaro, you’ll begin on the lowest 2.5mg weekly dose to allow your body to get used to the medication and lower the chance of side effects.

Most people do not see substantial weight loss until they reach a higher maintenance dose, usually between 10 and 15mg per week, but this depends on the person. Some people stay on a lower dose and still lose a lot of weight. As long as you do not get severe or ongoing side effects, you can keep increasing your dose every 4 weeks to the maximum dose.

➤ Learn more about the Mounjaro dosage schedule.

Mounjaro is not an overnight weight loss solution. It can take several weeks to months to notice any real changes to your weight and appearance. However, if you’re not getting the results you were expecting, there could be several reasons for this, ranging from being on the wrong dose, not making sufficient changes to your lifestyle, or hitting a plateau.

1. Too early to see results

If you have just started Mounjaro, your body is probably still adjusting to the medication.

Although some people may notice small weight changes in the first 4 to 6 weeks, it can take up to 12 weeks before you see any significant changes. During this time, focus on the positive changes, such as a reduction in your appetite, your clothes becoming baggier, or the fact that you might be snacking less.

And remember, it’s better to lose weight slowly than rapidly, as rapid weight loss can cause health problems like gallstones or hair loss.

2. Incorrect dosage or titration

It’s possible that you’re not yet on the optimal weight loss dose for you. The Mounjaro dosage schedule starts low and increases slowly to avoid side effects, like feeling or being sick. Your dose will gradually titrate up, usually every 4 weeks, until you reach the maximum maintenance dose of 15mg per week or whichever is the most comfortable for you.

It’s important that you follow the titration schedule and avoid skipping or missing injections for maximum effectiveness. Skipping or missing doses is likely to reduce the effectiveness of Mounjaro, and if you miss more than 2 doses, you’ll need to start the dosage schedule again.

3. Diet and calorie intake

Mounjaro works by binding to the receptors of GLP-1 and GIP to suppress your appetite, but it will be ineffective if you overeat or make poor food choices. If you’re consistently consuming more calories than you are burning, your weight loss will stall, or you could even gain weight.

Even when taking weight loss medication, you must be in a calorie deficit to help you lose weight. Some of the ways you can ensure you are doing this include:

• prioritising proteins, fibre-rich fruits and vegetables, and wholegrains
• avoiding ultra-processed, high-sugar foods and drinks
• being aware of your portion sizes
• tracking your calories so you can see how much you’re consuming each day, including any ‘hidden calories’, for instance, in drinks

➤ You can use our calorie deficit calculator to estimate your daily requirements.

4. Lack of physical activity

Although Mounjaro reduces your appetite, exercise can burn extra calories, boosting your metabolism and promoting fat loss. So, if you have not taken steps to increase your daily physical activity, this could be contributing to your lack of progress on Mounjaro.

You should aim to complete at least 150 minutes of exercise per week, with 2 sessions of strength or resistance training. It also helps to increase your general activity throughout the day, such as standing up and moving more, as this can all contribute to weight loss and maintenance.

5. Medical or metabolic conditions

Some health conditions and medications can interfere with weight loss progress, even when taking Mounjaro. Some of the health conditions that can impact your ability to lose weight include:

• polycystic ovary syndrome (PCOS)
• an underactive thyroid (hypothyroidism)
• insulin resistance or type 2 diabetes

There are also some medications that can make it harder to lose weight or contribute to weight gain, such as:

• corticosteroids
• antidepressants
• beta-blockers

6. Alcohol, sleep, or stress levels

Certain lifestyle habits can impact your progress with Mounjaro. Even with a reduced appetite, things like alcohol, poor sleep, and stress can lead to increased cravings and a slow metabolism. For example:

• alcohol can be high in calories and trigger overeating, which may mean you are not in a calorie deficit
• poor sleep can raise hunger hormone levels, like ghrelin, and lower leptin levels, which can contribute to a feeling of fullness
• chronic stress can raise cortisol levels, a stress hormone, which promotes fat storage and can slow down your metabolism, contributing to weight gain
• lack of exercise, which stress and poor sleep can together make it harder to find the energy to get moving and keep up with your exercise routines

7. Plateauing or water retention

If you had been making progress on Mounjaro, but it has recently stalled, you may have hit a plateau. Weight loss plateaus are common, with some research suggesting 85% of people will experience their weight loss slowing or reversing.

At the start of your journey, your rapid weight loss may have been the result of your body losing water. Fluid retention is common, usually temporary, and often results in rapid weight changes. However, losing fat is a slower, more gradual process and can take time.

You may also see a bigger drop in weight at the start of your journey if you make sudden, big changes to your lifestyle and diet, especially if you’re eating healthier and eating less.

Over time, your body will adjust to your new diet and exercise plan, and you will need to make further changes, such as:

We have more advice and tips on breaking through your weight loss plateau in our guide.

Although Mounjaro is effective for many people, it may not work for everyone. If you’ve been taking it for 6 months at a maintenance dose and made lifestyle changes, but still have not lost at least 5% of your starting weight, you may benefit from switching weight loss medications.

At Superdrug Online Doctor, we offer the following alternative treatments:

Wegovy

Wegovy is a weekly injection that contains the active ingredient, semaglutide. It is a GLP-1 receptor agonist, like Mounjaro. It works by reducing appetite and slowing digestion. Clinical trials show that it can help people lose an average 15% of their initial body weight at the highest dose over 68 weeks.

You can find out how to switch from Mounjaro to Wegovy in our guide. With Superdrug Online Doctor, you only need to wait 7 days between your last dose of Mounjaro and your first dose of Wegovy, so you can continue your weight loss journey with minimal disruption.

Nevolat

A generic liraglutide injection, previously available under the brand name Saxenda, Nevolat is also a GLP-1 receptor agonist. Unlike Mounjaro and Wegovy, it is a daily injection. Research shows that the average weight loss after 56 weeks on Nevolat is 8%.

Mysimba

Mysimba is a prescription-only weight loss tablet that works by controlling your appetite and acting on the reward centre of the brain to control eating habits, like snacking between meals. It contains 2 active ingredients, bupropion and naltrexone, and it can help you lose 8.1% of your starting body weight after 56 weeks of treatment, on average. Mysimba can only be prescribed privately.

Xenical (orlistat)

Xenical, also available in its generic orlistat form, is a prescription-only weight loss pill that works by blocking the absorption of dietary fat. The active ingredient, orlistat (120mg), has been shown to help people lose an average 5% of their body weight within 12 weeks.

Orlistat is also available over the counter at a lower 60mg dose under the brand name alli. Although you do not need a prescription, a pharmacist or healthcare professional will need to ask you a few questions to make sure it is safe and suitable for you to take.

Before you decide to switch from Mounjaro to Wegovy, Nevolat, or any other weight loss medication, there are a few things you can try to help restart your progress. It may be that you’ve hit a plateau, need to make a few more lifestyle adjustments, or increase your dose to see noticeable results.

Here are a few of our top tips to restart weight loss on Mounjaro:

If you’re not seeing the results you expected with Mounjaro, even though you have followed the prescribing instructions and made lifestyle changes, you should speak to your doctor. Everyone’s weight loss journey is different, and a medical review may help to uncover the reason behind stalled progress or a plateau, helping you to get back on track safely and effectively.

Speak to a doctor if you:

• have been taking Mounjaro for 6 months without meaningful weight loss (at least 5% of your starting weight)
• are not sure you are on the correct dosage
• are getting side effects or have missed several doses
• think you might have an underlying condition that’s affecting your results
• are taking any medication that may be interacting with Mounjaro

Whether you’re concerned about side effects, your progress, or want to maximise your progress, Superdrug Online Doctor can help.

How long does it take to lose weight on Mounjaro?

Some people will notice changes in their appetite and the way their clothes fit within the first few weeks of starting Mounjaro, but this can vary from person to person. Generally, if you have not lost at least 5% of your starting body weight within 6 months, your doctor will recommend you stop Mounjaro and try an alternative weight loss medication.

What if I’m gaining weight on Mounjaro?

Weight gain on Mounjaro can happen if you do not make the necessary lifestyle changes, such as following a diet and exercise plan. So, if you find you are gaining weight, it’s likely that you will need to adjust your diet, such as lowering your calorie intake or choosing healthier options, and/or increasing your exercise levels. If you have already made these changes, contact your doctor for more advice.

Is Mounjaro less effective for some people?

Yes, how your body responds to Mounjaro can depend on your genetics, hormones, lifestyle, and underlying medical conditions. So, for some people, Mounjaro may not be the most effective medication for them, and they may need to consider an alternative.

Do I need to change my diet on Mounjaro?

Yes, although there is no specific Mounjaro diet that you need to follow, it is important that you adjust your eating habits and eat a healthy, balanced diet to support your weight loss progress. A reduced-calorie diet is usually recommended, as this can help you achieve a calorie deficit, which will help you lose weight.

How often should I exercise on Mounjaro?

Ideally, you should aim to complete at least 150 minutes of moderate-intensity aerobic exercise each week, such as brisk walking, cycling, dancing, swimming, or team sports and 2 to 3 strength or resistance training sessions each week to promote lean muscle mass. However, activities such as taking the stairs instead of the lift, walking the dog, and even household chores can all count towards your daily exercise.

Can I skip a dose?

No, it is generally not recommended that you skip a Mounjaro dose because this can make it less effective. However, if you miss a dose and it has been:

• less than 4 days since your scheduled dose, take it as soon as you remember, then inject your usual dose on your normal scheduled day
• more than 4 days since your scheduled dose, skip the missed dose, then inject the next dose on your usual scheduled day

Never take a double dose to make up for a forgotten or missed dose, as this can increase the chance of severe side effects.