Mounjaro weight loss by week: Here's what you can expect

Mounjaro, a medication initially developed for managing type 2 diabetes, has gained significant attention for its efficacy as a weight loss drug.

If you've been prescribed Mounjaro, or are thinking about starting a weight loss treatment with the medication, you're likely curious about what to expect. How quickly will you start to notice a difference? How much weight could you lose in total? What side effects should you look out for?

We're here to answer all your questions. Read as we do a deep dive into what you can expect during your first few months on Mounjaro and what you can do to maximise your results.

How effective is Mounjaro?

Mounjaro, also known as tirzepatide, is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist.

That's a mouth full, we know, but the way it works is it mimics the hormones that regulate your blood sugar levels and appetite, in turn supporting weight loss by reducing your caloric intake.

And it seems to be more effective than some of its alternatives.

A study from 2022, for instance, found an average of 19.5% body weight loss in patients on tirzepatide after 52 weeks, compared to patients on semaglutide, who lost an average of 13.8% body weight over the same amount of weeks [1][2].

Now, while the effectiveness of Mounjaro for weight loss is supported by research, it's important to note that results may vary based on factors like your diet, exercise habits, and body composition.

Plus, medication shouldn't be seen as a quick fix, but rather one piece of the weight loss puzzle.

That's why Juniper's Weight Reset Programme includes not only weight loss drugs, but also unlimited support from our expert dietitians, a strength and cardio exercise plan to help you maintain muscle mass as you lose weight, tracking tools to keep you motivated, and access to a private community of women on the same journey as you.

Designed by UK clinicians, this programme gives you the tools you need to make informed decisions, so you can not only lose weight but keep it off well into the future.

What is a typical Moujaro dosing schedule?

For the first 4 weeks of treatment, your doctor will prescribe the starting dose, which is 2.5mg once a week.

Assuming your body responds well to the medication, you'll then go on an escalation schedule until you reach the maximum dosage:

You'll go through this schedule under the guidance of your doctor. To prevent adverse side effects, it's important that you take the exact dosage they recommend and only go up when they give you the go-ahead.

Mounjaro weight loss by week: What to expect

Here’s a detailed breakdown of what you can expect during the initial phase of treatment:

Weeks 1-2

During the first couple of weeks, you may start to notice subtle changes in your appetite and eating habits.

While significant weight loss typically doesn't happen immediately, some people experience a decrease in appetite and food noise, which is the first sign that Mounjaro is starting to work.

Since you're less hungry, you'll likely eat fewer calories and enter a caloric deficit, setting the stage for future weight loss.

It may be tempting to skip meals in an effort to speed up the weight loss process, but you should resist the temptation, as your body needs fuel to function properly. Plus, skipping meals is a slippery slope — you may end up feeling even hungrier and overeating later in the day.

At this stage, you may experience mild gastrointestinal side effects, like nausea, constipation, or diarrhoea. This is normal and the result of your body adjusting to the medication. With time, these symptoms should subside.

Take this time to improve your lifestyle: eat healthy and within your deficit, start incorporating more movement into your routine, and stay hydrated.

Weeks 3-4

As you enter the third week of Mounjaro, your body should be used to the 2.5mg starting dosage; and according to clinical trials, the average weight loss by week 4 is about 4% of the starting body weight [3].

However, different people lose weight at different rates. If you haven't made as much progress as you were expecting, don't let that discourage you. Remember that medical weight loss takes time and focus on what you can control: making healthy lifestyle choices every day.

Weeks 5-8

At week 5, your doctor may up your Mounjaro dosage to 5mg, as long as your body is tolerating the medication well, without any severe side effects.

By week 6, you may lose up to 6% of your starting weight, and by week 8, around 7% [3]. Excitingly, at this stage, you may also start to see a difference in the mirror and clothes may begin to fit differently.

And the benefits go beyond the physical. You may start to notice positive changes in your well-being as well — perhaps you have more energy, can sleep better, or feel like making healthier choices is becoming second nature.

Week 9 and beyond

After 8 weeks, it may be time for another dosage increase — provided your body continues to tolerate Mounjaro well. In that case, you'll move to a 7.5mg once weekly injection and as weeks go by, your dosage may increase until maintenance.

Weight loss should continue to happen steadily, but the pace at which it occurs may be slower than in the first few weeks.

To give you an idea of what may happen as you continue your Mounjaro journey, in a 2023 study, patients on tirzepatide achieved 21.1% mean weight loss by the end of a 36-week lead-in period and an additional 6.7% weight loss during a 52-week continued treatment period [4].

What if I stop losing weight?

Whether on Mounjaro or not, most people experience a weight loss plateau at some point in their journey, where the weight loss slows down or temporarily halts. This is normal, albeit frustrating.

If you find yourself plateauing, it's important not to get discouraged. Instead, see what small adjustments you can make to your diet or exercise routine, to kickstart the weight loss again.

Habits like eating more high-fibre foods, prioritising protein, increasing your daily step count, or trying new forms of exercise to keep your body challenged can all help.

How to manage Mounjaro side effects

Like any medication, Mounjaro can cause side effects, especially during the initial weeks of treatment. The most common side effects reported by users include nausea, vomiting, diarrhoea, and constipation.

These side effects are generally mild to moderate in severity and tend to diminish as your body becomes accustomed to the medication.

However, managing these side effects is crucial to ensure that you can stay on track with your weight loss journey. Here's how:

• Stick to your dosage schedule. There's a reason why you don't start Mounjaro on the highest dose — to let your body adjust to the medication and reduce the severity of your side effects.
• Eat smaller, more frequent meals. To manage nausea, consider eating smaller, more frequent meals throughout the day. Avoid large, heavy meals that can exacerbate the discomfort, and focus on light, easy-to-digest foods such as fruits, vegetables, lean proteins, and whole grains.
• Stay hydrated. Drinking plenty of water can help alleviate constipation, a common side effect of Mounjaro. Aim to drink at least 8-10 glasses of water a day and incorporate high-fibre foods into your diet to promote regular bowel movements.
• Monitor your symptoms. Keeping track of any side effects you experience can help you and your doctor make necessary tweaks to your treatment plan. If side effects persist or worsen, don't hesitate to reach out to them for advice.

There are also a few rarer, but more serious side effects to consider, including pancreatitis, gallbladder problems, hypoglycemia (low blood sugar), and severe digestive problems. If you're concerned about any of these, be sure to speak to your doctor.

Lifestyle tips for maximising Mounjaro weight loss

While Mounjaro can significantly aid in weight loss, combining it with healthy lifestyle changes can take your results to the next level. Here are some tips to help you get the most out of your treatment:

Maintain a balanced diet

A healthy, balanced diet is the foundation of any successful weight loss plan, so when you go grocery shopping, be sure to:

• Focus on whole foods, including lean proteins, fruits, vegetables, and whole grains.
• Steer clear of processed foods, sugary snacks, and high-calorie beverages

It's especially important that you consume high-fibre foods. Firstly, because it will help with the gastrointestinal side effects. But also, when you eat enough fibre, you feel fuller for longer, which helps to curb habits like compulsive snacking.

Protein is also crucial. It's the most satiating macronutrient and the one with the highest thermic effect, meaning your body burns more calories digesting protein than carbs or fats.

Exercise regularly

Exercise is essential for burning calories, maintaining (and building) muscle mass, and improving your overall health, both physical and mental.

The NHS recommends doing either 150 minutes of moderate exercise or 75 minutes of vigorous activity per week [5] — and there are many workout methods to choose from, including strength training, running, swimming, yoga, Pilates, jump roping, and more.

Get adequate sleep

Lack of sleep can lead to increased hunger, cravings for unhealthy foods, and reduced motivation to exercise, all of which can hinder your weight loss efforts.

To prevent this from happening and feel energised every day, aim for 7-9 hours of sleep per night, and establish a consistent sleep routine to improve the quality of your rest.

Manage stress

Chronic stress can cause you to emotionally eat and lead to cortisol-induced — weight gain that typically shows up around the midsection and is often referred to as a 'hormonal belly'.

To prevent stress from interfering with your weight loss progress, consider:

• Practicing mindful eating
• Starting a food diary
• Trying stress management techniques like meditation, deep breathing exercises, yoga, or mindfulness
• Improving your sleep hygiene

Stay consistent

Consistency is key to successful weight loss. Stick to your treatment plan, maintain healthy habits, celebrate all victories (big or small, scale-related or not) and be patient with your progress. Need some extra motivation? Check out our psychology-based weight loss tips and stay on track for good.

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