Mounjaro (Tirzepatide) is a once-weekly injectable medication. While it was originally approved for treating type 2 diabetes, doctors now also prescribe it for weight loss due to its impressive ability to curb appetite.(1)

If you're thinking about using Mounjaro for weight loss, here's everything you need to know about its effectiveness, safety, proper dosage, and answers to the most common questions. 

How Effective Is Mounjaro for Weight Loss?

• Mounjaro is currently the most effective weight-loss medications available today.
• Studies show that it can help reduce body weight by 15–21%
• More effective than Ozempic and other weight-loss injections and medications. (Ex. Ozempic typically leads to a weight loss of up to 15%.)(2)

What Are the Conditions for Using Mounjaro for Weight Loss?

A doctor may prescribe Mounjaro for weight loss in the following cases:(3)

• Obesity (Body Mass Index BMI of 30 or higher).
• Overweight (BMI 27 or higher) with at least one obesity related condition, such as diabetes, high blood pressure, or other health issues.
• No medical contraindications based on a doctor's evaluation, including:
  
  • A personal or family history of medullary thyroid cancer.
  • Multiple endocrine neoplasia type 2 (MEN2).
  • Allergy to any of its ingredients.

Note: You should inform the doctor if there is any history of pancreatitis, chronic kidney or liver disease, severe stomach disorders, or diabetic retinopathy. A thorough evaluation may be needed to determine whether using Mounjaro is safe for you in these health conditions.

How Does Mounjaro Help with Weight Loss?

Mounjaro works by suppressing appetite and slowing down stomach emptying, which makes you feel full faster and stay satisfied longer after eating. As a result, you naturally eat less and this leads to a  gradual loss of weight. (1)

How Much Weight Can the Body Lose with Mounjaro?

The amount of weight you lose with Mounjaro depends on the dosage and how your body responds to the medication, some people may lose more or less than expected.

However, according to clinical studies, the average weight loss after using Mounjaro for 16.5 months was: (4)

• 15% of body weight (around 16 kg) with a 5 mg weekly dose.
• 19.5% of body weight (around 20 kg) with a 10 mg weekly dose.
• 20.9% of body weight (around 23.6 kg) with a 15 mg weekly dose.

When Does Weight Loss Start After Starting using Mounjaro?

Mounjaro starts working within hours to days after the first dose, but noticeable weight loss usually takes a few weeks. Your doctor will monitor your progress and adjust the dosage based on your body’s response to the medication.(5)

How to Use Mounjaro for Weight Loss?

Mounjaro is given as a subcutaneous injection and comes in a pre-filled injection pen. (5)

• Treatment starts with a 2.5 mg dose once a week to allow the body to adjust with the medication.
• The doctor increases the dose after 4 weeks to 5 mg once a week .
• The dosage may be increased gradually based on how the body responds and tolerates the medication. The maintenance dose is typically 5 mg, 10 mg, or 15 mg once a week, as adviced by the doctor.

Note: Mounjaro weekly doses can be taken at any time of the day, with or without food.

How Long Should You Stay on Mounjaro? Will the Weight Come Back After Stopping It?

How long you stay on Mounjaro depends on your personal goals and the treatment plan you develop with your doctor. Generally, it’s designed for long-term use and can be taken safely under medical supervision only, especially if you need ongoing appetite control to maintain your weight loss.

Studies show that stopping Mounjaro may cause your appetite to return to its previous levels—or even increase in some cases—which can lead to weight regain. That’s why, if you're thinking about stopping Mounjaro, it’s important to work with your doctor to put a sustainable diet and exercise plan to help maintain your achieved results. (6)

What Are the Side Effects of Mounjaro?

Mounjaro is generally safe when used correctly and under medical supervision.

Common Side Effects (Affect more than 5% of users, usually temporary and improve within the first few weeks):(7)

• Nausea (most common).
• Vomiting.
• Diarrhea or constipation.
• Stomach pain, indigestion.
• Fatigue and low energy.
• Burping.
• Hair loss (due to reduced food intake and rapid weight loss).

Serious Side Effects (Less common but still possible) and includes:

• Severe stomach, kidney, or gallbladder issues.
• Inflammation of the pancreas.
• Low blood sugar or what is called (hypoglycemia).
• Severe allergic reactions.
• Depression.
• Vision changes.

Make sure to  stop Mounjaro and Call Your Doctor Immediately if you experience one of the below: 

• Severe, sharp stomach pain (possible sign of pancreatitis).
• Low blood sugar symptoms, such as dizziness, excessive sweating, and confusion.
• Rapid heartbeat.
• Signs of a severe allergic reaction, including swelling of the face, lips, tongue, or throat, or a rash with intense itching.
• Vision changes.
• Yellowing of the skin or eyes or what is called (jaundice).
• Fever.

Please note that symptoms may not appear until later stages, so it’s essential to use Mounjaro under medical supervision and do regular check-ups while taking the medication.

If you are thinking of starting to use Mounjaro, talk to a specialist to find out if it’s right for you and how to use it safely. Book an appointment today with the Endocrinology Department.

References

1. New England Journal of Medicine - Tirzepatide Once Weekly for the Treatment of Obesity 
2. Drugs.com - How do Ozempic, Mounjaro, Wegovy, Zepbound compare for weight loss?
3. FDA - FDA Approves New Medication for Chronic Weight Management
4. Nature Medicine - Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial
5. NCBI Bookshelf - Tirzepatide - StatPearls 
6. GoodRx - Zepbound FAQs: Here’s How Tirzepatide Works for Weight Loss‍
7. FDA - HIGHLIGHTS OF PRESCRIBING INFORMATION These highlights do not include all the information needed to use ZEPBOUND safely and effe