Mounjaro (Tirzepatide): How does it work for weight loss?

There are a number of weight loss medications on the market; from Wegovy to Saxenda, Orlistat and Rybelsus.

The latest medication gaining traction is Mounjaro and for good reason — this medication has proved to be incredibly effective for weight loss.

How does Mounjaro lead to more effective weight loss outcomes? What exactly is it? And, how much weight can you lose, when combining this medication with lifestyle changes? Here's what you need to know.

What is Mounjaro?

Mounjaro (pronounced Mown-JARH-OH) is a dual-action medication that is highly effective for weight loss. This medication is delivered by subcutaneous injection once a week.

In official terms, Mounjaro is a long-acting dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist [1].

The active ingredient in Mounjaro is called tirzepatide. For context, medications like Wegovy, Rybelsus and Ozempic contain the active ingredient semaglutide, while Saxenda contains liraglutide.

How does Mounjaro work?

Mounjaro works slightly differently from GLP-1 medications, like Wegovy, as it activates both GLP-1 and another hormone called GIP, which helps to promote fat loss, block fat gain and regulate blood sugar.

By combining the effects of GIP and GLP-1 together, Mounjaro is more effective at promoting weight loss through decreased appetite, as well as directly impacting the pathways that lead to fat loss.

To simplify this a bit, this medication helps to reduce your appetite (making you feel fuller far more quickly), assists with turning down cravings, helps improve blood glucose levels and stimulates the breakdown of fat.

Another difference between tirzepatide and a GLP-1 medication like semaglutide is the dosages. Mounjaro is a much higher dose of medication, starting at 2.5mg and going up to 15mg. Wegovy dosages start at 0.25mg and go up to 2.4mg [2].

How effective is Mounjaro?

According to clinical trials, tirzepatide is one of the most effective medications for weight loss that is available. There have been a number of studies on the results of Mounjaro and it outperforms other GLP-1 medications.

One study from July 2022 found an average of 19.5% body weight loss in patients on tirzepatide after 52 weeks, compared to average patients on semaglutide, who lost an average of 13.8% body weight over the same amount of weeks [3][4].

Can you switch from another GLP-1 medication to Mounjaro?

Yes, you can move from another GLP-1 medication, like semaglutide or liraglutide, onto tirzepatide but you'll need to consult with your healthcare provider on how best to do this.

It's important to note that regardless of the dose of your previous medication, you'll need to start on the lowest dosage of Mounjaro, which is 2.5mg, and slowly increase your dosage over a period of time.

How to administer Mounjaro

As with other GLP-1 medications, tirzepatide is administered via a subcutaneous (under the skin) injection. While this can sound intimidating, it is something that people tend to get used to fairly quickly.

The best places to administer the injection on the body are the upper thigh, upper arm or stomach. A number of medications of this nature are delivered like this because it allows for a slow sustained rate of absorption and your body is able to continuously deliver the medication at a low dose [5].

Plus, a number of medications simply aren't absorbed well by the digestive tract or are destroyed by the acid and digestive enzymes in the stomach, which is why an injection is preferred as it bypasses this process [6].

Can you take Mounjaro a day early?

Yes, it's usually fine to take your Mounjaro dose a day early or a day late, but you need to leave at least 3 days (72 hours) between doses. Keep this in mind if contemplating moving your Mounjaro day.

Can you take 2.5mg of Mounjaro twice to make 5mg?

We recommend consulting your prescriber before administering two doses but, if you're already on the 5mg dose and only have 2.5mg pens, it should be fine to use 2 of these to make up your full dose. Just be sure to not inject them in the same spot. If you haven't yet worked up to the 5mg dose, do not take 2 doses of Mounjaro within 3 days of each other.

What are the common side effects of Mounjaro?

As with all medications, there is a chance you may experience side effects when using Mounjaro.

The most common side effects of Mounjaro are similar to those you may experience with other GLP-1 medications, like Wegovy, including nausea, vomiting, diarrhoea, abdominal pain, constipation and indigestion.

The good news is that these side effects generally subside as your body adjusts to the medication and should calm down after a few weeks. If you're continuing to experience side effects, it's best to consult your healthcare provider or prescriber for advice.

How to manage the side effects of Mounjaro

For the short-term or more mild symptoms associated with taking Mounjaro, like nausea, it can help to try the following [7]:

• Eat bland, low-fat foods
• Eat smaller meals and stop when you're feeling full
• Increase both your water and fibre intake

If you're experiencing prolonged side effects, be sure to discuss these with your health practitioner who may advise reducing the medication dose to help mitigate these symptoms.

Rare but serious side effects

There are a handful of more serious side effects that, while rare, can occur so it's important to be across these. These include [8]:

• Hypersensitivity reactions: Serious hypersensitivity reactions, like anaphylaxis and angioedema, have been reported. Discontinue tirzepatide if a serious allergic reaction is suspected and seek medical advice.
• Gastrointestinal disease: The use of tirzepatide has been associated with gastrointestinal adverse reactions that could be severe.
• Acute gallbladder disease: This has occurred in clinical trials and shouldn't be used by people with a history of gallstones without cholecystectomy.

These concerns should be discussed with a healthcare provider when determining whether this treatment is suitable or not.

Who shouldn't take Mounjaro

Tirzepatide can't be used by some of the population — below is a list of people who should avoid this medication [8].

• If you have a personal or family history of a type of thyroid cancer called medullary thyroid carcinoma (MTC)
• If you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
• If you are allergic to tirzepatide or any of the ingredients in Mounjaro
• If you are pregnant, breastfeeding or actively trying to conceive
• If you have type 1 diabetes
• If you have a history of pancreatitis (note: people who have had a cholecystectomy may be able to commence treatment but be sure to discuss this with your practitioner)
• If you take an insulin secretagogue or are on insulin therapy
• If you have non-proliferative diabetic retinopathy requiring acute therapy, proliferative diabetic retinopathy, or diabetic macular oedema

What happens when you stop taking Mounjaro?

When you transition off Mounjaro, you'll likely notice your appetite increase again, which is something to keep in mind as you get used to be off the medication, so you don't regain the weight you lost. It's important that you speak with a healthcare professional before you stop taking Mounjaro, so they can guide you through the transition.

How long does Mounjaro stay in your system?

Mounjaro typically stays in your system for about 30 days.

Is Mounjaro available in the UK?

Mounjaro is available in the UK and is a medication option included in our Weight Reset Programme.

Our program takes a holistic approach to weight loss and includes treatment from UK-registered clinicians, dietitian-led health coaching and tracking as well as free, unlimited consultations with prescribers.

Making lifestyle and behaviour changes through health coaching is important for keeping weight off in the long-term and our team of experts equips you with the tools and support to do this.

Plus, the use of a clinically proven medication helps to kickstart this weight loss.

If you'd like more information about the Juniper Weight Reset Programme, you can get in touch with our team via email (hello@myjuniper.co.uk).