Why you may not be losing weight on Mounjaro

Before I get into why Mounjaro might not be working for you, I first want to briefly explain the science behind how the weight loss treatment actually works. That way, you can better understand what’s going on in your body when you take it.

How Mounjaro works:

1. Dual hormone activation: Mounjaro works by mimicking two hormones found naturally in the body: GLP-1 and GIP.
2. Suppresses appetite: These hormones send signals to your brain that you are full, making you less hungry and causing you to eat less.
3. Slows digestion: Mounjaro causes food to stay in your stomach for longer, meaning the food you eat keeps you full for longer.
4. Regulates insulin: Stimulates the production of insulin, lowering blood sugar and preventing glucose spikes.

The effects of mounjaro also depend on the dose you take, as I will explain next. If you would like a more detailed explanation, you can read our dedicated guide on how Mounjaro works for weight loss.

When you first use Mounjaro, you must start on the lowest dose: 2.5 mg. Only after you have been on this dose for at least 4 weeks can you move on to the next dose.

While this is done to help ease you into treatment and reduce the risk of side effects, it’s also far less effective than higher doses. This typically means you won’t lose much fat in your first month.

One clinical trial found that most people only tend to lose around 1-2% of their overall weight in the first 4 weeks. However, this same study shows you can lose up to 21% after 72 weeks.

You can also read our detailed guide on what to expect during your first month on Mounjaro for more information.

Mounjaro isn’t a magic treatment, and meaningful weight loss relies on other factors. Based on my experience, here are the 10 most common reasons people struggle to lose weight on Mounjaro.

1. It’s too early

Weight loss with Mounjaro takes time, and the most likely reason you aren’t losing weight in the early stages of treatment is simply that you haven’t been taking it for long enough.

Remember, everybody responds differently to treatment. While some people see results straight away, others find that the first month is more about getting used to the medicine.

If you’ve only just started treatment, remember that progress takes time, and you may simply not have been taking it for long enough for noticeable weight loss.

2. A plateau

It’s completely normal for weight loss to slow down for a bit during treatment, even if you’ve seen good results up until then. This is known as a plateau.

Weight loss is rarely a straight line. During treatment, your body can often go through phases of more or less weight loss, especially when you’re changing doses.

You may also go through periods of adjustment when your body is getting used to your new, lower weight. This is called metabolic adaptation, and it involves your body trying to preserve its energy stores.

While this can cause the scale to stall for a while, don’t be discouraged. This doesn’t mean the treatment has stopped working. Weight loss plateaus should pass within weeks, so long as you stay consistent with your treatment and continue to maintain a healthy diet and regular physical activity.

3. Calories and nutrition

Because Mounjaro works by making you eat less, weight loss happens gradually as your body uses stored fat for energy, bit by bit.

That’s why Mounjaro is always prescribed alongside a nutritious, calorie-reduced diet. When taking Mounjaro, make sure you're eating less than you normally would, while still maintaining a balanced, nutrient-dense diet.

Inhalation of ipratropium bromide is associated with fewer systemic side effects compared to other routes of administration, such as oral or intravenous, due to its localised action in the lungs.

Dr. Caroline Fontana Lead Prescribing Doctor

4. You’re not drinking enough water

Food isn’t the only thing to think about when trying to lose weight with Mounjaro; water matters as well.

Hydration is one of the most important factors influencing your metabolism, which helps your body utilise nutrients better, potentially reducing cravings.

Proper hydration also helps with digestion, with the added benefit of easing side effects like nausea and bloating.

Tip:

The European Food Safety Authority recommends a minimum of 2,500 ml of water per day for men and 2,000 ml for women, but you can benefit from drinking more.

5. You’re not getting enough physical activity

The calories you eat need to be lower than the calories you burn for weight loss to be possible. This is known as a calorie deficit.

This is far easier to achieve if you engage in regular physical activity. By maintaining an exercise routine, you can burn more calories and, therefore, lose more fat.

The World Health Organisation recommends adults do at least 150 minutes of moderate-intensity physical activity throughout the week, but if you are trying to lose weight, you may benefit from doing more.

Remember:

Physical activity isn’t just running and lifting weights. Whatever exercise looks like for you, everything counts. The key is consistency.

6. Changes in muscle mass

Weight training can strengthen muscles, and muscles are heavy. In fact, muscles are denser than fat and can significantly affect your weight on the scale, even if you are losing fat at the same time. If you’re lifting weights during treatment with Mounjaro and not seeing the scale move, it may be that you are building muscle mass while losing fat.

However, it is also important to consider that rapid weight loss may lead to a loss of lean muscle mass if not managed properly. When you are in a significant calorie deficit, the body may sometimes break down muscle tissue for energy.

To protect your lean mass, I recommend prioritising protein-rich foods and incorporating resistance training into your weekly routine. While research on Mounjaro’s impact on muscle mass is ongoing, maintaining strength is an important part of healthy, long-term weight loss success.

7. Medical conditions or medications

Certain medical conditions or prescription medications can get in the way of your weight loss goals, and you may not always realise it.

Conditions that may cause issues with weight loss include:

Medicines that can interfere with weight loss include:

Keep in mind::

These conditions and medications will not always interfere with weight loss, and to varying degrees if they do. Your doctor will take your entire health profile into consideration when prescribing treatment to ensure safety.

8. Overindulging on alcohol

Alcohol is high in calories and doesn’t offer much in the way of nutrients. That means it increases your overall calorie intake without making you full or providing your body with much energy.

This makes it very hard to stay within a calorie deficit and lose weight. If you are struggling to lose weight on Mounjaro, consider the effect alcohol is having on your diet. Even if you don’t eat much, alcohol can more than make up for lost calories.

Also, because your body cannot store alcohol, it prioritises burning these calories over fat stores. This can slow down your weight loss progress, especially if you are drinking more than 14 units per week.

9. Stress and sleep

High stress levels and poor sleep can increase hormones like cortisol and ghrelin, which can both interfere with your weight loss efforts.

High stress means high cortisol. And high cortisol levels can encourage the body to store fat, particularly around the belly. This can counteract some of the benefits of Mounjaro.

And poor sleep can interfere with ghrelin, the hormone that makes you hungry, and leptin, which makes you feel full. This can cause increased hunger and cravings, making it difficult to maintain the calorie deficit needed for weight loss.

To ensure low stress and proper sleep hygiene, consider implementing the following into your routine:

10. Mounjaro isn’t right for you

Finally, it is possible that Mounjaro simply isn’t the right weight loss treatment for you. While highly effective for many, individual responses to treatment can differ, and another treatment may be better suited to your needs.

If you have been taking Mounjaro for a while and you still aren’t seeing noticeable weight loss, don’t be discouraged. It may be that a medicine like Wegovy or Saxenda is a better fit.

Start your consultation with euroClinix now, and our registered doctors can determine the most effective treatment for you.

While Mounjaro is a powerful tool, it works best when combined with sustainable lifestyle habits. To maximise your success, I recommend the following: